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Frogs as potential biological control agents in the rice fields of Chitwan, Nepal
Abstract
Anuran frogs are often considered generalist predators in rice fields and feed upon a variety of invertebrates. They may thus provide an invaluable ecosystem service, as many species belonging to the orders coleoptera, lepidoptera, orthoptera, homoptera and hemiptera are regarded as notorious rice pests, inflicting significant losses on rice production. In this study, we surveyed frogs in rice paddies of lowland Nepal during the dry and rainy seasons, approximately 3–4 weeks after rice had been planted. We used stomach flushing to study the dietary habits of anuran species encountered, and provide empirical evidence of the ecological service provided by frogs in this agricultural landscape. We found that frogs included a high proportion of crop pests in their diet, but consumption of pests varied between the rainy and dry seasons, frog species and even individual frogs. The ecosystem services provided by frogs are not limited to crop pest control, but, as our observations revealed, include consumption of a large number insects known to be important vectors of zoonotic diseases. We encourage both farmers and conservation planners to consider frogs as important biological pest controllers during the development of pest management and strategies in agricultural landscapes.
... Anurans are described as generalist predators feeding upon variety of invertebrates, including molluscs, annelids, centipedes, millipedes, arachnids, crustaceans and especially insects (Anderson et al. 1999). Few studies of diets of Anurans from Nepal shows the largest proportion of insect pests of crop with high seasonal variation (Parajuli et al. 2005, Khatiwada et al. 2016 although no more evidences are found. Some of the major Anuran diet consists of insects of order Coleoptera, Lepidoptera, Orthoptera, Homoptera and Hemiptera (Mahan and Johnson 2007) but Hymenoptera was abundant followed by Coleoptera and Lepidoptera in Nepal (Khatiwada et al. 2016). ...
... Few studies of diets of Anurans from Nepal shows the largest proportion of insect pests of crop with high seasonal variation (Parajuli et al. 2005, Khatiwada et al. 2016 although no more evidences are found. Some of the major Anuran diet consists of insects of order Coleoptera, Lepidoptera, Orthoptera, Homoptera and Hemiptera (Mahan and Johnson 2007) but Hymenoptera was abundant followed by Coleoptera and Lepidoptera in Nepal (Khatiwada et al. 2016). Large frogs also feed upon small fishes and other frogs (Duellman and Trueb 1986), cannibalism is frequently seen among frogs (Crump 1992). ...
... Some small sized frog may also consume other frogs which even secret bufotoxin, the term called Batracophagy (Ceron et al. 2018). Frog diet is not only limited to the crop pest, they also feed upon variety of insects which are known to be important vectors of zoonotic diseases (Khatiwada et al. 2016) and also acts as important biological control agent for pests and helps in ecosystem management (Chowdhary et al. 2018). ...
... This study was carried out between May to September from 2014 to 2018 at several sites in the eastern, central, western and far-western part of Nepal Himalaya extends between 80°04' -88°12' E and 26°22' -30°27' N ( Figure 1). Amphibians were surveyed using visual encounter surveys, acoustic surveys, and leaf litter searches during at night (19 : 00-00 : 00) (detailed survey methods can be found in: Khatiwada et al., 2016Khatiwada et al., , 2019b. Specimens were collected by hands, euthanized, tissue samples collected and fixed in 4% formalin for 24 hrs, then preserved in 70% ethanol. ...
... They are active soon after sunset. They primarily feed on ants and other insects (Khatiwada et al., 2016). In hot subtropical environments of lower elevational zones of Tarai, Nepal, the breeding is from late February to August. ...
... This toad is mostly nocturnal. They primarily feed on ants and other insects (Khatiwada et al., 2016). In hot subtropical environments of lower elevational zones of tarai, Nepal, the breeding is initiated from late February to August. ...
Amphibians are declining worldwide. At the same time, each year many species of amphibians are described, indicating that biological diversity on Earth remains poorly understood. This is especially true for mountainous regions, such as the Himalayas, which are also regarded as a biodiversity hotspot. However, it is most likely that the current diversity of amphibians in Nepal is highly underestimated. Amphibian inventories by the past researchers primarily used phenotypic characters as the basis for species identification. However, the application of molecular systematics methods to taxonomic studies has successfully uncovered the taxonomic status of several cryptic taxa. This study used both molecular (16S rDNA sequences) and morphological comparisons and estimated the diversity of amphibians from Nepal. This study reports the occurrence of 38 species of amphibians based on both molecular and morphological comparisons. Among them, three species were recorded for the first time in Nepal. This study also invalids the taxonomic status of Sphaerotheca paschima. This study highlights the importance of integrative taxonomic approaches that help to resolve the current taxonomic ambiguities of Nepalese amphibians.
... The diet of frogs and toads is influenced by their foraging behaviour (Taigen and Pough 1983;Mo 2015), including predominant habitat use (Hodgkison and Hero 2003;Kovács et al. 2007), foraging distance from breeding ponds (Mahan and Johnson 2007), reproductive behaviour (Kovács et al. 2007) and available energy for predation (Taigen and Pough 1983). Diet may also be influenced by competition (Glorioso et al. 2010), prey availability (Labanick 1976), seasonality and prey selectivity (Hodgkison and Hero 2003;Khatiwada et al. 2016), climate and environmental conditions (Main et al. 1959), time spent in aestivation (Reilly et al. 2013;White and Pyke 2015), the habitat type occupied (Bower et al. 2014) and morphological and ontogenetic factors (Labanick 1976;Emerson 1985;Hodgkison and Hero 2003). Diet studies may therefore provide important biological information (e.g. ...
... Some invasive amphibians provide benefits to native species or ecosystems (Shine 2014;Ferreira et al. 2015), and L. cyclorhyncha could potentially also have beneficial impacts. Frogs play an important role in the trophic interactions and food webs of natural and novel ecosystems (Zacharow et al. 2003;Kupfer et al. 2006;Hui 2015;Khatiwada et al. 2016) and alien species may perform fundamental ecosystem services that other species are unable to provide (Hayward 2009). Frogs, for example, may consume arthropods that pose a threat to crops or animal and human health (Khatiwada et al. 2016). ...
... Frogs play an important role in the trophic interactions and food webs of natural and novel ecosystems (Zacharow et al. 2003;Kupfer et al. 2006;Hui 2015;Khatiwada et al. 2016) and alien species may perform fundamental ecosystem services that other species are unable to provide (Hayward 2009). Frogs, for example, may consume arthropods that pose a threat to crops or animal and human health (Khatiwada et al. 2016). The lifecycle of frogs encompasses aquatic and terrestrial environments and enables energy flow between ecosystems (Kupfer et al. 2006;Huckembeck et al. 2014). ...
Litoria cyclorhyncha (Hylidae) is native to southern Western Australia, but a naturalised population has established on the Eyre Peninsula, South Australia. We investigated the diet of this exotic population to assess potential impacts on biodiversity and ecosystems. Seventy-six frogs were collected from three different habitats and their diet items assigned to parataxonomic units (PU) within orders. Stomach contents were diverse, containing 467 prey items from 19 orders and 135 PU, with extrapolation suggesting a diet of ~200 PU. Shannon diversity estimates of prey items consumed produced different rankings for the three habitats at the PU and order level. Therefore, estimates at the order level may not be representative of the actual diversity of prey items. L. cyclorhyncha consumed mainly arthropods and low numbers of conspecific young frogs, geckos and a juvenile house mouse. This generalist, indiscriminate predatory diet is similar to that of other hylids and implies that the species poses a risk to native biodiversity and ecosystem processes by predation and competition. Therefore, further spread of this species needs to be prevented. Our findings can inform effective policies and management actions to mitigate future impacts of L. cyclorhyncha.
... Amphibian communities were sampled within 3 months in both 2014 and 2015 (from May to July, coincide with the rainy season) using nocturnal time constrained visual encounter and acoustic aids surveys, which is an effective method to cover entire amphibian community including terrestrial, arboreal, aquatic as well as fossorial and even well-camouflaged species [42][43][44]. This method involved four people systematically walking at a slow pace, intensively searching for amphibian species by turning over the stones, logs, leaf litters, tress branches, shrub and bushes along the transects (100 m × 4 m) [44]. ...
... Amphibian communities were sampled within 3 months in both 2014 and 2015 (from May to July, coincide with the rainy season) using nocturnal time constrained visual encounter and acoustic aids surveys, which is an effective method to cover entire amphibian community including terrestrial, arboreal, aquatic as well as fossorial and even well-camouflaged species [42][43][44]. This method involved four people systematically walking at a slow pace, intensively searching for amphibian species by turning over the stones, logs, leaf litters, tress branches, shrub and bushes along the transects (100 m × 4 m) [44]. The searches were conducted using 220 lm torches and each transect was searched for 1 h between 19:00 h and 23:00 h after the sun set every night, with one to three transects being sampled per night [44]. ...
... This method involved four people systematically walking at a slow pace, intensively searching for amphibian species by turning over the stones, logs, leaf litters, tress branches, shrub and bushes along the transects (100 m × 4 m) [44]. The searches were conducted using 220 lm torches and each transect was searched for 1 h between 19:00 h and 23:00 h after the sun set every night, with one to three transects being sampled per night [44]. In total, 79 sites located in different elevations between 78 and 3430 m ( Fig. 1) were sampled within 2 years field work, with each site was sampled only once in the sampling period. ...
Background
Species richness and composition pattern of amphibians along elevation gradients in eastern Nepal Himalaya are rarely investigated. This is a first ever study in the Himalayan elevation gradient, the world’s highest mountain range and are highly sensitive to the effects of recent global changes. The aim of the present study was to assess amphibian community structure along elevation gradients and identify the potential drivers that regulate community structures. Amphibian assemblages were sampled within 3 months in both 2014 and 2015 (from May to July) using nocturnal time constrained and acoustic aids visual encounter surveys. In total, 79 transects between 78 and 4200 m asl were sampled within 2 years field work. A combination of polynomial regression, generalized linear models, hierarchical partitioning and canonical correspondence analysis were used to determine the effects of elevation and environmental variables on species richness, abundance, and composition of amphibian communities.
Results
Species richness and abundance declined linearly with increasing elevation, which did not support the Mid-Domain Model. Among all the environmental variables, elevation, surface area and humidity were the best predictors of species richness, abundance and composition of amphibians. The majority of amphibian species had narrow elevation ranges. There was no significant correlation between species range size and elevation gradients. However, body size significantly increased along elevation gradients, indicating that Bergmann’s rule is valid for amphibians in eastern Nepal Himalaya.
Conclusions
This study indicates that eastern Nepal Himalaya is a hotspot in amphibian diversity, and it should be served as a baseline for management and conservation activities.
Electronic supplementary material
The online version of this article (10.1186/s12898-019-0234-z) contains supplementary material, which is available to authorized users.
... Irrigated rice cropping systems serve the dual role of providing an essential food crop to the world's most populous regions (Muthayya et al., 2014) and functioning as man-made wetlands that harbor a diversity of organisms (Elphick, 2000;Natuhara, 2013). Diverse amphibian fauna have been documented in rice fields throughout Asia (Bambaradeniya et al., 2004;Holzer et al., 2017;Kanagavel et al., 2017) and South America (Duré et al., 2008), and in some countries, such as Nepal, as many as 13 different species have been recorded (Khatiwada et al., 2016). Amphibians are also experiencing rapid global population declines (Rowley et al., 2010;Wake and Vredenburg, 2008), and irrigated rice fields offer valuable alternative habitat for larval, ecosystems amphibians have been recognized for providing several ecosystem services that benefit humans either directly or indirectly, including pest control, nutrient input, bioturbation, providing a protein source for local populations, and serving as indicators of environmental contamination (Hocking and Babbitt, 2014;Liu et al., 2011;Valencia-Aguilar et al., 2013). ...
... Evidence suggests that amphibians could provide important pest control services in rice fields (Khatiwada et al., 2016;Teng et al., 2016). Native amphibians inhabiting rice fields in Nepal were observed to regularly consume herbivorous rice pests such as the rice green leafhopper (Nephotettix spp.), the oriental armyworm (Mythimna spp.), and rice root and water weevils (Echinocnemus spp. ...
... Native amphibians inhabiting rice fields in Nepal were observed to regularly consume herbivorous rice pests such as the rice green leafhopper (Nephotettix spp.), the oriental armyworm (Mythimna spp.), and rice root and water weevils (Echinocnemus spp. and Lissorhoptrus spp.) (Khatiwada et al., 2016). In China, populations of rice leaf rollers, stem borers, and plant hoppers were significantly reduced when non-native Chinese bullfrogs (Hoplobatrachus rugulosus) were added to enclosed experimental rice fields, and the addition of frogs also improved yields (Teng et al., 2016). ...
Lowland irrigated rice fields serve the dual purpose of providing an essential food crop to the world's most populous regions and functioning as man-made wetlands that harbor a diversity of organisms. Amphibians occupy rice fields throughout Asia and South America, but little is known about their functional role in the rice ecosystem. We conducted field surveys in Los Baños, Philippines over two separate rainy seasons (2015 and 2017) to determine whether native Luzon wart frogs and invasive cane toads consume rice pests, and if so, which species was more effective in doing so. We also examined diet composition to test whether the two species compete for food resources in rice fields. We found that despite smaller body sizes, the Luzon wart frog consumed the same total mass of prey as the cane toad (although it consumed fewer total prey items), and that pests made up the largest proportion (54.1%) of its total diet. In contrast, the majority (89.4%) of the cane toad's diet consisted of beneficial arthropod predators. Taxonomic analyses of diet composition and breadth revealed that the diet of Luzon wart frog was distinct from that of the cane toad, although there was overlap, and that both species consumed diverse array of prey. Taken together, these data suggest adult Luzon wart frogs may provide effective pest control services, and that they may not be in direct competition over food resources with adult cane toads in rice fields. We also present the first evidence suggesting that cane toads may indirectly damage rice crops by consuming beneficial predators integral to the function of lowland rice ecosystems. We suggest that rice agro-ecosystems should be managed to promote species such as the native Luzon wart frog, and to reduce populations of the introduced cane toad in order to safeguard native biodiversity while simultaneously improving yields and reducing insecticide input.
... But some plant extract botanicals are also seen against rice pests (Aryal et al., 2018;Shitiri et al., 2014;Dutta and Roy, 2022). Beside these most popular controlling methods usually mechanical and cultural control strategies include mechanical synchronised planting, cultivation of certain rice varieties like Pusa Basmati-1 as trap crop, soaking sprouted seed in synthetic pesticide, seedling root dipping in pesticide and fertilizer, remove, burn or plough the stubbles, and using of fish, frog ducklings etc. also seem to be useful for controlling these pest population (Ayelo et al., 2021;Khatiwada et al., 2016;Bhatt et al., 2018). Some attractant sex pheromones like, (Z)-11 hexadecinal, (Z)-9-hexadecenal, (Z)-ll-hexadecenal, (Z)-9-octadecenal are show good efficacy in mass trapping and mating disruption of deleterious insect pests (Liu et al.,2020;Dang et al., 2016;Gunawardena and Ranatunga, 1989). ...
... Hamilton, 1822), Clarias batrachus (Linnaeus, 1758), Punctius ticto (F. Hamilton, 1822), frogs like, Euphlyctis cyanophlyctis, Duttaphrynus melanostictus (Schneider, 1799) etc. and Anas poecilorhyncha (Forster, 1781) are preyed on adult of rice pest thereby reduce the population(Khatiwada et al., 2016;Yuan et al., 2022). ...
West Bengal is considered a large producer state of rice in India with an output of nearly 55.48% of total crop production of Bengal. In West Bengal, rice has grown in three different cropping seasons such as Aus (autumn rice), Aman (winter rice) and Boro (summer rice), contributing about 20.69% to the total net State Domestic Product (SDP). Rice production in West Bengal hampered by many biotic stresses mostly by stem borers [Scirphophaga incertulas (Walker, 1863), Sesamia inference (Walker, 1856), Chilo polychrysus (Meyrick, 1932), Chilo suppressalis(Meyrick, 1863)] leaf folder [Cnaphalocrocis medinalis (Guenee, 1854)], plant hoppers [Nilaparvata lugens(Stal, 1854), Sogatella furcifera (Horvath, 1899)], leaf hoppers [Nephotettix virescens (Distant, 1908), Nephotettix nigropictus (Stal, 1870)], rice hispa [Dicladispa armigera (Olivier, 1808)], rice bugs [Leptocorisa acuta (Thunberg, 1783), Leptocorisa oratorius (Fabricius, 1794), Brevennia rehi (Lindinger, 1943)], gall midge [Orseolia oryzae (Wood-Mason, 1889)], etc. Demographic parameter has shown that rice pests are greatly affecting rice host either caused directly by creating dead heart (DH), hopperburn, onion leaf, silver shoot during different stages of harvesting or by indirectly transmitting grassy stunt virus (RGSV), rice ragged stunt virus (RRSV), rice tungro viruses (RTV), rice tungro bacilliform virus (RTBV) etc. resulting 9.5% production loss. For minimize the infestation farmers use different rice varieties which provide resistance effect in pest population. For controlling rice pest population farmers mostly use chemical insecticide [e.g. fipronil, acephate, fipronil, monocrotophos] which exhibit good results against rice pests. Beside those other techniques including using biological and biochemical pesticides [neem oil, karanj oil, mahua oil, conidial suspension of M. anisopliae], pheromones [(Z)-11-hexadecinal, (Z)-9-hexadecenal], allomones [5: 1 mixture of 2-(E)-octenyl acetate and octanol 3-octenal], cultutal methods [synchronized planting, using of trap crop etc.] are effective for controlling rice pests. The population ecology based sustainable management of such pest species will support E 3 strategy [Ecosystem service-based ecological engineering for ecological pest management (ESS-EE-EPM)] of pest management for successful cultivation of rice in the near future.
... Amphibians have long been recognized as potential natural predators of crop pests (Hamer et al., 2004;Loman and Lardner, 2006) being both generalist and opportunist predators (Mahan and Johnson, 2007). Khatiwada et al. (2016) reported a high proportion of rice pests in frogs' diet and recommended the introduction of frogs for biological pest control in rice fields. A sizeable abundance of amphibians is regarded as being efficient in bringing down the rice pest population (Teng et al., 2016;Fang et al., 2019). ...
... Our study shows frogs exhibit a preference for arthropod predators over pests, especially at a lesser density (Table 2, Fig. 4). The diet of amphibians in croplands has been found to be dominated by non-pests (94% of diet) (Brown, 1974;Khatiwada et al. 2016). Lisiecki (2019) also highlights the absence of any significant effect of lizards on crop damage due to intraguild predation on the beneficial arthropods. ...
Agricultural intensification is a major driver of biodiversity loss. However, the exact impacts of such loss of key ecosystem service (ES) provisions in agriculture require more scrutiny. We assessed the population loss impacts of a key ES-providing species in an agricultural landscape. We tested the hypothesis that intensive agriculture causes density reduction of frogs known as pest regulators and that negatively affects pest regulation. Different frog densities (high and low) observed in a previous study in low and high agricultural intensification areas were used as treatments in a semi-controlled field experiment. Functional response of the frog species was also studied. Neither high nor low frog density had any significant effect on respective pest populations. Limited feeding rate of the frog species might have contributed to reduced predation pressure on pests. Surprisingly, at low density, frogs significantly reduced the arthropod natural enemies, probably their preferred prey due to the latter’s agility. Unlike in low frog density treatment, increased intraspecific competition at high frog density made them seek out pests as alternative prey to the preferred arthropod pest enemies, whose populations were not affected by frog density. This study for the first time links the population loss of frogs, a potential bio-control agent to ES provision in a multi-trophic system.
... Amphibians have been recommended as an effective biological control for paddy pests (Teng et al., 2015;Khatiwada et al., 2016;Fang et al., 2019). Loss of amphibians from rice fields (Tsuji et al., 2011;Qiu, 2012;Liu et al., 2013;Xie et al., 2014) shows instances of pest outbreak and ultimately yield loss (Hamer et al., 2004;Knutson et al., 2004;Gibbs et al., 2005;Loman and Lardner, 2006). ...
... Rice paddy cultivation in Asia contributes 89% to global rice cultivation (Rana et al., 2007;Khatiwada et al., 2016). India occupies a 41.85 million hectare area under rice crop with an annual production of 133.70 million tonnes (Churpal, Koshta and Choudhury, 2015). ...
... Indeed, amphibians play important functional roles in ecosystems, contributing to some key ecosystem processes. For instance, they can regulate food webs and biogeochemical cycles through predation and competition (Khatiwada et al., 2016). Typically, animal functional roles were reflected by their morphology (Sun et al., 2021a;Villéger et al., 2017). ...
... Each transect was sampled only once, and one to three transects were sampled per night during the sampling processes. Details of the sampling protocols have been provided in Khatiwada et al., (2016). All the individuals encountered were captured in the field with the help of native field guides. ...
Biological diversity is a concept that contains multiple facets, of which functional diversity is considered to be more integrative to describe the relationship between biodiversity and ecosystem functioning. In recent decades, functional diversity patterns have been assessed along elevational gradients in plants and birds. However, few empirical studies have been conducted to reveal amphibian functional diversity patterns between elevational zonations on mountains. In the present study, we investigated amphibian ecomorphologically functional diversity patterns in different elevational zonations of Nepal Himalaya. Our results indicated that functional space occupied by amphibian assemblages differed in size between elevational zonations, with assemblages in zonation-2 (500-1300 m) occupying the highest proportion. In terms of the position in functional space, assemblages in low elevational zonations (zonation 1 & 2) differed significantly from those in high elevational zonations (zonation 3-5). Distribution of individuals in the five assemblages along the six axes of the functional space was significantly different between most pairs of comparisons, while the difference varied between assemblages along axes. Interestingly, despite morphologically extreme amphibians accounted for small proportions of the total number of amphibians, they filled a large proportion of the six dimensional functional space. More importantly, most of the extreme amphibians were also the most functional uniqueness individuals, and they were widely distributed in all the zonations. Therefore, functional vulnerability of amphibian assemblages exists throughout all the elevational zonations. Accordingly, extreme amphibians with most functional uniqueness should be in particular well protected to maintain amphibian functional diversity. Further research can explore the mechanism underlying the unique amphibian functional diversity patterns in Nepal Himalaya.
... Frogs and tadpoles also significantly add to disease vector control (Propper et al. 2020;Murugan et al. 2015;Bowatte et al. 2013). In the absence of frogs, insect numbers and other agricultural pests may rise, resulting in increased use of pesticides (Khatiwada et al. 2016;Oza 1990). ...
... Over-exploitation of frogs does not only cause the collapse of targeted populations but also has a much broader impact, the so-called "Ripple-effect", which impacts the ecological balance, causing a cascade of plagues of insects, snails and other prey of frogs, resulting in agricultural harvest losses, increased use of toxic and expensive pesticides, and increase of related risks for humans and ecosystems (Proper et al. 2020;Khatiwada et al. 2016;Truong 2000;Abdulali 1985). Such consequences illustrate the complexity of these interrelationships, on which harvest and trade of wild frog populations are largely based. ...
According to EUROSTAT (the European statistics database) the EU has been importing about 40,700 tonnes of frogs’ legs within the period 2011-2020, which
correlates with 814 million to 2 billion frogs. Most of these animals are still caught from the wild. The report analysis the impact on wild frog populations in the supplying countries (e.g. Indonesia, Turkey or Albania) and the consequences of the uncontrolled frogs' legs trade on ecosystems. Furthermore, recommendations are given on how this trade needs to be internationally regulated.
... Many amphibian species have a high degree of resistance to human disturbance and persist in human-dominated landscapes (Schleich and Kästle 2002). For example, frogs are widespread in rice paddy fields (Bambaradeniya et al. 2004) and these semiaquatic agro-ecosystems can harbor relatively high amphibian diversity, up to 13 species (Khatiwada et al. 2016). Lowland Nepal provides important habitat for amphibians (Khatiwada and Haugaasen 2015;Khatiwada et al. 2017Khatiwada et al. , 2019 and is also a rice-growing region. ...
... Some detailed studies of anuran diets have been conducted in rice paddy fields (Hirai and Matsui 2002;Yousaf et al. 2010;Piatti and Souza 2011), but few have been conducted in Nepal (Khatiwada et al. 2016). Information on the natural history and the biology of most amphibians of lowland Nepal is poorly known. ...
Many studies have documented dietary habits and resource competition among sympatric amphibians, but few have focused on anuran diets in paddy fields. We studied the dietary habits of five sympatric amphibian species in the lowland paddy fields of Nepal. We extracted 685 prey items belonging to 13 major prey categories. The most frequent prey belonged to Hymenoptera, Coleoptera, Lepidoptera, Diptera, Hemiptera, and Orthoptera. Among them, Hymenoptera and Coleoptera were the most abundant prey categories. We recorded the highest prey abundance from the Asian Common Toad (Duttaphrynus melanostictus). We compared dry and rainy season diets and found similar compositions with high dietary overlap among the focal species: D. melanostictus, Common Skittering Frog (Euphlyctis cyanophlyctis), Jerdon's Bullfrog (Hoplobatrachus crassus), Asian Bullfrog (Hoplobatrachus tigerinus), and Terai Cricket Frog (Minervarya teraiensis). The differences in prey consumption we observed were associated with variation in body size and feeding strategy (e.g., sit and wait vs. active search) and may facilitate coexistence. Our findings highlight the need for a detailed study on the ecology of rice paddy amphibians and their diets.
... They are all the more vulnerable due to their cryptic habit and sensitivity to microhabitat changes (Valentine et al. 2007). Although recent studies have highlighted their ecological roles in the agricultural systems-little is known on the subject (Khatiwada et al. 2016;Teng et al. 2016). ...
... In our study, some farmers even put forth the idea of maintaining herpetofauna in agricultural land for efficient biological pest control. This has been shown in ecological studies by Teng et al. (2016), Fang et al. (2019), and Khatiwada et al. (2016). Surprisingly farmers mentioning Checkered keelback capable of pest regulation also has been proved in a study by Hossain (2016) where the study showed their diet consisting majorly of arthropods. ...
Systematic appraisal of community’s knowledge as evidence for biodiversity conservation has been widely recognized. For conserving the rich biodiversity in the rural landscape outside the protected areas, it is important to document the knowledge and perception of the farming community. Although such appraisal is available for different taxa, no such systematic study is available for herpetofauna- one of the most vulnerable faunal groups. Our study attempts to document the impact of agricultural intensification on herpetofauna in an agricultural landscape through knowledge and perception appraisal of the farming community. A semi-structured questionnaire survey and validation was conducted in areas of low, medium, and high agricultural intensification. In all areas, farmers indicated an overall decrease in herpetofauna abundance. Farmers at the mid and high agricultural intensification zones reported a more significant decrease in herpetofauna sightings specifically for amphibians and snakes compared to those under low intensification regions. Farmers at low intensification area recognized significantly more herpetofauna. Farmers attributed five major threats to herpetofauna and ranked pesticide as the most significant reason, especially those in higher intensification. The majority were aware of the importance of herpetofauna as a biological pest control agent. Level of education or farming experience did not seem to have any influence on the farmers’ knowledge. Our findings integrated with other quantitative studies will facilitate future community-driven conservation in the studied agricultural landscapes.
... Depending upon the nature of use, the pesticides are insecticides, fungicides, nematicides, rodenticides and biopesticides. Khatiwada et al., (2016) reported 13 species of frogs in rice paddies which consume large population of rice pest especially during dry seasons and also nd frogs signicance for farmers. Frogs belong to order anura have signicantly consumed different species of rice pest belongs to the order coleoptera, lepidoptera, orthoptera, homoptera and Hemiptera. ...
... More research is required in the eld of pesticides effect and their adverse effect on decline of amphibian in agricultural areas. There is an urgent need to conserve amphibians' species by both government and farmer level and also mention frogs importance in pest management practices (Khatiwada et al., 2016). The author suggest that frogs are friends for farmer (FFF= frogs friends of farmer). ...
Amphibians are vital for proper functioning of an ecosystem. Different genera of frogs and toads play a dual role as prey and predator in an ecosystem. The most important role is they act as a food for higher chordates like snakes, birds and mammals. Due to huge use of pesticides and chemical fertilizer in agriculture sector is one of the important cause of decline of amphibian population in the world. On medical point of view they are very signicant in controlling the different genera of mosquitoes like Anopheles, Aedes and Culex which are responsible for malaria, yellow fever and dengue in human population. The rice eld lled with water give opportunity to frogs to live in that in return they control insect and pest of rice crops.
... Kim et al. 2019). Amphibians are in-fact, a vital component of agroecosystems as they consume insects and other arthropods considered as crop pests (Pandian and Marian 1986;Bambaradeniya et al. 2004;Natuhara 2013;Khatiwada et al. 2016). However, they are among the most threatened vertebrates and are declining globally both in and outside of protected areas (Stuart et al. 2004;Sodhi et al. 2008;Burivalova et al. 2014). ...
... Anurans are an important component of agricultural fields such as rice-paddy cultivation and several arthropods consumed by them are considered crop pests (Khatiwada et al. 2016). Anurans are perceived as efficient bio-control agents (Pandian and Marian 1986) but with sparse evidence. ...
Rice-paddy agriculture is widely expanding, particularly in Asia. Rice-paddy fields are stagnated with water and insecticides are applied to control pests. Expansion of agriculture and pesticide are known drivers of declining amphibian populations globally. Yet, several amphibians persist in such temporary wetlands. How amphibians persist in this landscape matrix is not clearly understood. We document amphibian diversity in rice-paddy fields in south India and examine trophic interactions of the two most abundant species. From 60 rice paddy fields, we recorded six species of anurans among which, Minervarya caperata and Microhyla ornata were most abundant. The stomach contents of 57 individuals of the two species were extracted. They consumed prey items belonging to eight orders and 56 taxonomically distinct units dominated by Diptera and Hymenoptera: Formicidae. Although individuals of M. ornata were smaller in body size compared to M. caperata, both species consumed a similar number of arthropods. The dietary niche breadth of M. caperata was wider than M. ornata and the diets of the two species did not overlap greatly. We discuss our findings in the context of prey availability, foraging strategies, and highlight the role of anurans in pest control.
... Fieldwork was carried out from May to July in 2014 and 2015, coinciding with the rainy season and the breeding period of amphibians in Nepal (Khatiwada et al., 2016). In total, 79 transects (100 m � 4 m) were sampled after sunset (between 19:00 h and 23:00 h) using nocturnal time-constrained visual encounter surveys ( Fig. 1), covering an altitudinal range from 78 m to 4200 m. ...
... Amphibians are widely distributed in eastern Nepal Himalaya. They inhabit a variety of ecosystems and provide important ecosystem services for local human societies (Khatiwada et al., 2016). In recent years, studies have increasingly started to focus on the taxa in this area in terms of taxonomy (Khatiwada et al., 2015(Khatiwada et al., , 2017, community (Khatiwada et al., 2019), and distribution modeling (Subba et al., 2018). ...
Understanding the thermal ecology of active amphibians, as well as its relationship with habitat and environmental features, is a central theme in ecology. However, this topic has been poorly studied in eastern Himalaya, which is a global biodiversity hotspot. To bridge this gap, we investigated how the body temperatures of active amphibians varied along an elevation gradient in the Arun and Tamor River catchments in eastern Nepal Himalaya in the present study. Amphibian assemblages were sampled from May to July in both 2014 and 2015 using nocturnal time-constrained visual encounter surveys, and the body temperature of each individual was directly measured using a digital infrared thermometer in the field. A combination of linear regression and hierarchical partitioning analyses was used to determine the effects of elevation and environmental variables on the body temperatures of active amphibians. In total, the body temperatures of 599 amphibian individuals belonging to 28 species from six families were recorded. Our results indicated that amphibian body temperature exhibited monotonically declining trends with increasing elevations in eastern Nepal Himalaya. Interestingly, this tread was much more pronounced in subtropical (lowland) areas than in warm and cool temperate regions. Inter- and intraspecies variations in body temperature were large, which can be attributed to distinct habitat utilization among species and the change in vegetation cover in different bioclimatic zones. Among all environmental variables, substrate temperature and water temperature were the best predictors of the amphibian body temperature. Overall, this study revealed amphibian body temperature patterns along an elevation gradient in eastern Nepal Himalaya, which were principally driven by temperature-related environmental factors. We believe our results can provide important information on amphibian physiological traits, which may help ecologists predict their responses to future climate change and formulate protection strategies.
... Research on biocontrol of BPH in rice has historically been conducted by entomologists, and concentrated on the contribution of arthropod natural enemies, such as spiders, predatory beetles, parasitoids and ladybeetles (Chiu 1979;Shepard et al., 1987;Settle et al., 1996;Heong et al., 2015b). However, recent studies have shown that frogs are important predators of BPH, potentially having a larger contribution to BPH mortality than arthropod natural enemies (Khatiwada et al., 2016;Zou et al., 2017). That the role of frogs in biocontrol of BPH has been underappreciated until recently can be explained by the widespread use of techniques for measuring predation rates that are unsuitable to quantify predation by frogs, for instance use of immobilized prey (Zou et al., 2017). ...
... Second, predation pressure is higher in the evening than during day time, and third, mortality rate was highest at the start of the experiment when BPH densities were still relatively high, but quickly decreased after that. Our study confirms the findings of Zou et al. (2017) and Khatiwada et al. (2016) that frogs are the main predators of BPH. In the study area Rana limnocharis is the most common species of frog (Xiao, unpublished data). ...
The brown plant hopper, Nilaparvata lugens Stål, is a major rice pest in South-East Asia. While brown plant hopper (BPH) populations can be regulated by natural enemies, there is limited quantitative information available about the contribution of different predator species to BPH mortality. Our study has three aims: (i) assess the relative contribution of different predator species to BPH mortality in rice fields, (ii) assess diurnal patterns in BPH predation, and (iii) assess the seasonal variation in BPH predation. We quantified predation of live mobile BPH in three rice fields using video recording and assessed densities frogs, a major predator group, by direct counts. In 864 h of video recording, 102 mortality events were observed. Frogs (Ranidae), wolf spiders (Lycosidae) and jumping spiders (Salticidae) were the main predators, accounting for 76%, 13% and 9% of the BPH predation events, respectively. There were large differences in frog density across fields, and there was more predation during the evening (63% predation events) than during the day (37%). Survival analysis indicated that predation risk quickly decreased with time after the onset of recording sessions and that most predation happened within the first 10 min. The results confirm the often overlooked contribution of frogs to BPH predation, but also highlight the substantial variation in predator pressure and frog abundance across farmers’ fields. While camera observations provide compelling information on the identity and relative importance of natural enemies in predation of pests, further development of methods is needed to minimize possible biases resulting from disturbance when making camera observations to quantify predation risk.
... Aquatic frogs (Anura) are one of the most characteristic inhabitants of rice fields (Seshadri et al. 2020). Here, they constitute a vital part of food chains, serving as either predators (by feeding on crustaceans and insects) or prey for many waterfowl and small mammals (Khatiwada et al. 2016;Do et al. 2021). Aquatic frogs have a biphasic life cycle (aquatic and terrestrial) and semi-permeable skin, making them vulnerable to agrochemical exposure (Jones et al. 2009;Mann et al. 2009;Pérez-Iglesias et al. 2015). ...
We present the results of an in situ study of a set of blood parameters in adult marsh frogs (Pelophylax ridibundus (Pallas 1771) from populations inhabiting the largest system of rice fields in Bulgaria, the Tsalapitsa rice fields (TRF), under chronic stress conditions. This study was conducted in spring 2022 to assess the health status of TRF frogs compared to that of frogs occupying a reference site (RS). Furthermore, this study also compared the results obtained for the TRF population with those obtained in a study conducted at the exact same location with P. ridibundus individuals in 2013 (Zhelev et al. 2018). This comparison highlights the potential effects of persistent use of agrochemicals (pesticides and fertilizers) on the marsh frogs of later generations. Our results suggest that the general health of marsh frogs in the polluted site (PS) in southern Bulgaria has severely deteriorated. Frogs of both sexes were anemic with weakened immune systems compared to those living in the RS. The long-term use of agrochemicals in the PS affected males to a greater extent than it did females. Statistically significant hypochromia was observed in males, combined with general leukopenia, neutrophilia, lymphopenia, monocytosis, eosinophilia, and higher neutrophil/lymphocyte (N/L) ratios.
... Amphibians provide several regulatory services including reducing human-insect vector populations and consuming agricultural crop pests (Hocking and Babbitt 2014;Shuman-Goodier et al. 2019;Khatiwada et al. 2016). Because their early life stage is aquatic, they also function as bio-monitors for developmental problems associated with chemical contamination. ...
Rice agriculture provides wetlands and complex habitats supporting biodiversity. Wetlands associated with rice agriculture since the 1960s have increased by 32% and now form nearly 12% of wetlands globally at a time when vast areas of natural wetlands are being lost. In this chapter, we set our sights beyond Sustainable Development Goal (SDG) 2 that focuses on ending hunger and achieving food security via the promotion of sustainable agriculture. Often, agricultural scientists are so motivated to achieve food security that they pay insufficient attention to the need to have a healthy and dynamic agroecosystem that promotes floral and faunal biodiversity, which may also provide ecosystem services including support for food security of smallholder families. Because of their aquatic, semi-aquatic, and terrestrial ecological phases, rice fields represent a changing mosaic of ecological niches and have the potential to sustain a broad diversity of wildlife. In addition, a multitude of studies have investigated how modifications to rice cultivation have the potential to support a greater diversity of species across biological scales while often maintaining or increasing yield. SDG 15 emphasizes the need to promote sustainable use of terrestrial ecosystems and halt biodiversity loss. Given the high losses in global biodiversity, especially in tropical zones where most of the world’s rice is grown, we set our sights on achieving both SDGs 2 and 15. We provide case studies on amphibians, bats, birds, and rodents living in and around irrigated rice-cropping systems. We report on transdisciplinary studies supported by CORIGAP that include agronomic, sociological, ecological, biochemical, environmental physiological, and genomic studies. Most of these studies identify potential positive ecosystem services provided by wildlife, which can lead to more sustainable and healthier rice production landscapes. We conclude that our current management of rice landscapes contributes to the biodiversity crisis. Rice production often overuses pesticides and fertilizers and applies unsustainable intensification practices and land modifications, which result in biodiversity loss. Finding a balance, where human population requirements for food are met without degrading the natural environment, is critical to the health of smallholder agricultural communities. We propose that future research and development projects need to: build capacity of countries to scale-up use of proven practices that reduce rice farming’s ecological footprint and conserve biodiversity, increase investment in biodiversity research in rice production landscapes, promote Green “Rice Value Chains” and “Agri-input Markets,” and monitor and evaluate the ecological benefits to biodiversity of broadscale promotion of sustainable rice production.
... In the opinion of Khatiwada et al, (2017), livelihoods of individuals or households are said to be sustainable when they are resilient in the face of external shocks and stresses; are not dependent upon external support (or if they are, this support itself should be economically and institutionally sustainable); maintain the long-term productivity of resources; and do not undermine the livelihoods of, or compromise the livelihood options open to, others Sustainable livelihood as an approach is people-centered in a direct sense, and depends upon the involvement of those meant to be helped by change. Indeed, this is both a principled and practical stance as it is hard to imagine being able to carry out sustainable livelihood without the involvement of people that are meant to be helped by change (Morse et al, 2009). ...
This study assessed women and sustainable livelihoods with focus on selected shea butter processing centers in Sagnarigu Municipal Assembly of the Northern Region, Ghana. The objectives of the study were to determine the challenges confronting women into shea butter processing and to examine the extent to which these challenges undermine sustainable livelihood of women. This study adopted the explanatory research designs with the quantitative research strategy. The study used structured questionnaire to gather data from 240 women. The study used Structural Equation Model to identify the challenges that significantly undermine sustainable livelihood of women. Start-up capital and credit for equipment, raw material and labor were financial challenges. Leadership, conflicts on transparency and accountability and social status were social challenges. Inadequate technical skills, poor management skills, poor record keeping were human capital challenges. Poor road network, inadequate storage facilities were physical challenges. Poor community and governmental relationship was the major institutional challenge. This study recommends urgent need to address institutional, natural capital and financial challenges confronting women into shea butter processing in the study area.
... Recently, rice-fishery co-culturing has become a popular strategy to ensure the key ecological functions and economic benefits of the ecosystem (Khatiwada et al., 2016;Khumairoh et al., 2021;Yu et al., 2023;Zhang et al., 2016); however, people are worried about food security in this mode. For example, in Jianli County, Hubei Province, China, paddy fields are commonly used to raise crayfish, but not rice, mainly because the price of aquatic animals is much higher than that of rice . ...
Rice–crayfish co-culturing is an important ecological agricultural mode in China that has been rapidly developed because of its considerable environmental and economic advantages. However, the combined impacts of optimizing nitrogen fertilizer practices on grain yield and greenhouse gas emissions of rice–crayfish co-culture systems were not clear. In this study, four treatments were implemented, that is, a control treatment (CK), conventional fertilization treatment (CON), optimized fertilization treatment (OPT), and combined application of normal and controlled-release urea (CRF). The static chamber-gas chromatography method was used to study the dynamic emission characteristics of methane and nitrous oxide in rice–crayfish co-culture fields from 2021 to 2022, and their global warming potential and greenhouse gas emission intensity were evaluated. The results showed that the average rice yield and nitrogen fertilization partial productivity of the CRF treatment were 9444 kg ha–1 and 45.0 kg (kg N)–1, respectively, which were 0.1%–12.4% and 7.2%–19.1% higher than those of the other treatments. Furthermore, the CRF treatment decreased the cumulative emissions of methane and nitrous oxide by 22.2%–38.3% and 25.5%–33.2% respectively, compared with those of the CON and OPT treatments. The global warming potential and greenhouse gas emission intensity of the CRF treatment were 3181 and 0.35 kg CO2-eq kg–1, respectively, which were 20.9%–47.0% and 25.0%–57.6% lower than those of the other treatments; therefore, the CRF treatment was the optimal fertilization strategy. Among the three nitrogen fertilizer treatments, methane emissions accounted for 80.3–90.5% of global warming potential, while nitrous oxide accounted for 9.5%–19.7%. Additionally, relevant analyses showed that water-dissolved oxygen was the dominant factor driving methane emissions in the rice–crayfish coculture fields. This study shows that rice–crayfish co-culturing can achieve synergy in maintaining rice yield and mitigating greenhouse gas emissions by optimizing fertilization strategies.
... The use of chemicals, aside from being harmful to humans, causes the destruction of ecosystems and adversely affects soil and water [43]. Encouraging farmers to turn to organic farming can result in more excellent benefits for the ecosystem [44]. As for the inorganic rice paddy, the relationship between the number of insectivorous birds, and the number of insect pests had a moderate level of relevance [38]. ...
Birds play a vital role in rice cultivation as organisms that help maintain the ecological balance and help eliminate pests very effectively. However, various pests at each phase of rice growth, and the use of pesticides may cause differences in the bird species found in rice paddy. The objective of this research was to explore the species of birds found in organic rice paddy and inorganic rice paddy, and during each phase of rice growth, in Doi Kaew Subdistrict, Chom Thong District, Chiang Mai Province, Thailand. The bird data was collected between April and November 2018. Insects were also collected during each growth phase of rice to investigate the relationship with the number of birds found. There were 65 species found in the survey. Most of the birds were insectivores and belonged to Order Passeriformes. Birds found in the planted area were more similar to the organic rice paddy than the inorganic rice paddy. The values of Shannon Wienner's diversity index (H'), Simpson's index (λ), and Margalef's index (D) of the planted area were at the highest level, followed by the inorganic rice paddy and organic rice paddy, respectively. Birds discovered in both paddies were statistically different (p<0.05), and the bird found during each phase of rice growth were statistically different (p<0.05). Even so, the birds that presented in each habitat were more similar to each other than other habitat types. The correlation between insectivorous birds and insect pests was positive in both rice paddy types, indicating that if there were more insect pests, there would be more birds as well.
... Frogs are also one of the most threatened vertebrate taxa globally (Wake and Vredenburg 2008). In recent years, studies of frogs as predators of rice pests in Southeast Asia have shown that they prey heavily on planthoppers (Delphacidae) and other pest insects (Khatiwada et al. 2016;Zou et al. 2017;Hemerik et al. 2018). However, because frogs feed on a variety of organisms, including beneficial arthropods (Shuman- Goodier et al. 2019), their role in pest suppression is unclear. ...
Frogs are both an organism in high conservation need and an important pest control agent in paddy ecosystems, but studies on the determinants of their abundance and their ecological roles in rice paddy fields are limited. Here, we investigated how the abundances of the Tokyo daruma pond frog (Pelophylax porosa porosa), Japanese brown frog (Rana japonica), and Japanese tree frog (Dryophytes japonica), which are common frogs in paddy fields, are affected by agricultural practices and landscape factors. We found that environmentally friendly farming practices had a positive effect on P. porosa porosa abundance, whereas landscape factors other than rice paddies (forests and buildings) had a negative effect. A surrounding forest positively affected R. japonica abundance, while buildings had a negative effect. Agricultural practices had no effect on D. japonica abundance, only building had a negative effect. Examination of the diet of P. porosa porosa, the species sensitive to environmentally friendly farming practices, showed that 20–30% of individuals ate both rice pests (mainly the rice water weevil, Lissorhoptrus oryzophilus) and their natural enemies (spiders). However, no difference was found in the species diversity or family composition of arthropods in the frogs’ stomachs or in the frequency of pest and spider predation between rice paddies with different agricultural practices, probably because of the small spatial scale of the study area. These results suggest that P. porosa porosa in particular feeds on both pests and natural enemies, and that the predation effects by frogs on rice pests are context dependent.
... Vertebrates have been often neglected as CBC agents; however, recent evidence shows that several groups such as amphibians, birds, and mammals provide an important pest control service in crops (Riccucci and Lanza 2014;Khatiwada et al. 2016;Garcia et al. 2020). In our analysis, we found that in the Neotropics, most studies have been focused on pest control provided by birds and mammals. ...
The history and recent developments of conservation biological control (CBC) in the context of industrialized and small-scale agriculture are discussed from theoretical framework available in the Neotropical region. A historical perspective is presented in terms of the transition of the way pests have been controlled since ancestral times, while some of these techniques persist in some areas cultivated on a small-scale agriculture. The context of industrialized agriculture sets the stage for the transition from chemical pesticides promoted in the green revolution to the more modern concept of IPM and finds in conservation biological an important strategy in relation to more sustainable pest management options meeting new consumer demands for cleaner products and services. However, it also noted that conservation, considered within a more integrative approach, establishes its foundations on an overall increase in floral biodiversity, that is, transversal to both small-scale and industrialized areas. In the latter case, we present examples where industrialized agriculture is implementing valuable efforts in the direction of conservation and new technologies are envisioned within more sustainable plant production systems and organizational commitment having that conservation biological control has become instrumental to environmental management plans. In addition, a metanalysis on the principal organisms associated with conservation efforts is presented. Here, we found that hymenopteran parasitoids resulted in the most studied group, followed by predators, where arachnids constitute a well-represented group, while predatory vertebrates are neglected in terms of reports on CBC. Our final remarks describe new avenues of research needed and highlight the need of cooperation networks to propose research, public outreach, and adoption as strategic to educate costumers and participants on the importance of conservation as main tool in sustainable pest management.
... Frogs' diverse sizes and habitats make them effective predators of various arthropods [44], recognizing them as biological control agents for various insects, including agricultural pests. Frogs can be used as environmental-friendly biological control agents because they are indigenous to their habitat and do not contribute to other environmental problems due to their natural role in ecosystems [45,46], such as those in the Lesti upstream rivers. However, the effects of agrochemicals, such as pesticides, are dangerous because the Anura becomes indirectly affected as a non-target organism [47,48,49]. ...
In Bromo Tengger Semeru National Park (BTSNP), buffer zone areas, one of which is the Lesti upstream rivers, play a critical role in sustaining biodiversity and community life. Frogs serve as a bioindicator of environmental change, particularly in the upstream rivers of the Lesti. The present study examines the diversity and community structure of Anura in the upstream rivers of Lesti, which are included in the BTSNP buffer zones. Throughout the surveys, up to 14 anuran species were encountered in four sites adjacent to the BTSNP border and crossed by the Lesti rivers. This study suggests that buffer zones may support herpetofaunal diversity by allowing humans to interact with them and sustainably utilize the resources in the areas. Urban development and conservation in these areas must be kept current in order to minimize environmental disruption caused by humans
... Microhyla taraiensis, Uperodon globulosus and Uperodon taprobanica). These species were usually farmland-dwelling, and they exhibited specific functional traits when compared to those of stream-dwelling species (Khatiwada et al., 2016;2021). For the phylogenetic diversity, the highest SES. ...
Aim
Exploring the mechanism underlying community assembly processes is considered as one of the central topics for biogeography. As one of the biodiversity hotspots, Nepal Himalaya has attracted increasing attention during the past decade. However, the main processes shaping amphibian assemblages in this area are still unclear. Here, we examined the elevational patterns of amphibian functional and phylogenetic structures to understand the main mechanism driving amphibian assemblages along an elevational gradient in eastern Nepal Himalaya.
Location
Eastern Nepal Himalaya.
Methods
Amphibian taxonomic, functional and phylogenetic diversity were calculated, and their responses to the increasing elevations were investigated based on the linear regressions. The environmental determinants of amphibian diversity were revealed based on the incorporation of generalized linear models and hierarchical partitioning analyses. In addition, the mechanism driving amphibian assemblages from low to high elevations was tested by calculating the mean pairwise functional distance and the mean pairwise phylogenetic distance indices.
Results
Amphibian taxonomic, functional and phylogenetic diversity had contrast responses to the increasing elevations, which were strongly determined by variables such as air temperature, the number of trees, leaf litter cover and water pH. Interestingly, the trends of amphibian functional and phylogenetic diversity along an elevational gradient can be changed after controlling the effects of species richness. Moreover, determining process played a dominant role in shaping amphibian assemblages with the increasing elevations.
Conclusions
Our results revealed the elevational patterns of amphibian functional and phylogenetic structures in eastern Nepal Himalaya, associated with the change in environmental variables. We also highlighted the dominant role of determining process in shaping amphibian assemblages. Overall, our results can help ecologists and managers better understand and formulate amphibian diversity conservation. In addition, our results also enriched the fundamental knowledge to understand the general patterns of community assembly rules in montane ecosystems.
... The work of Guo et al. demonstrates clearly how co-cultures could make agriculture more sustainable, by increasing soil fertility and reducing the need for fertilizers or pesticides. Moreover, these coupled systems could also help fight the spread of malaria by introducing natural, co-culturing predators, such as frogs (which eat the mosquitos) and fish (which eat the mosquito larvae), and so contribute towards several 'Sustainable Development Goals' of the United Nations (Khatiwada et al., 2016;Campanhola and Pandey, 2019). ...
When you eat rice with fish – or rice with crab or shrimp – you probably do not think about where the food came from. And if you do, you probably think that the rice grew in a paddy field, while the fish, crab or shrimp were caught in the sea. However, this may only be partially true. Systems for growing rice and various aquatic animals together have existed for over 1,200 years, but the practice of ‘co-culture’ has only recently gained the attention of the major rice-producing nations and the scientific community (Xie et al., 2011).
... Mundialmente podemos observar una gran diversidad de anfibios, siendo Colombia, el segundo país mas rico en especies de anfibios, al tener aproximadamente 763 especies de las cuales 367 son endémicas (Andrade, 2011). Dentro de la clase Amphibia se encuentra el orden Anura, organismos comúnmente conocidos como ranas y sapos (Pessier, 2018), estos individuos cumplen roles ecosistémicos muy importantes, ya que actúan como bioindicadores de calidad ambiental, debido a su amplia relación con su entorno físico (Bartelt et al., 2010) y además actúan como biocontroladores de plagas transmisoras de enfermedades zoonóticas (Hocking & Babbitt, 2014) y/o plagas de cultivos de uso alimenticio (Khatiwada et al., 2016). No obstante, a pesar de la importancia de estos individuos para el ecosistema, en Colombia las especies de anuros se encuentran ampliamente amenazadas debido a factores principalmente antrópicos, como lo son la fragmentación de su hábitat, sobreexplotación de recursos, introducción de especies exóticas, agricultura, manejo de cultivos ilícitos, contaminación, entre otros (Camacho & Mejía, 2017;Andrade, 2011;Rueda-Almonacid et al., 2004). ...
RESUMEN La especie Dendropsophus molitor, comúnmente conocida como Rana Sabanera, pertenece a la Clase Amphibia, específicamente al Orden Anura. Esta especie al igual que la población en general de anfibios, se han visto afectados por la actividad antrópica, como lo es la agricultura y el manejo de cultivos ilícitos en Colombia, en especial, debido a las estrategias que emplean para su control, siendo el herbicida a base de glifosato, Roundup activo, empleado en esta actividad. Una de estas estrategias es el uso de herbicidas a base de glifosato, como lo es Roundup activo®, empleados como controladores de malezas. Sin embargo, las últimas investigaciones han demostrado que estas sustancias tienen efectos tóxicos en los organismos que están expuestos con la misma, siendo los anfibios unos de los más afectados y con ellos su microbiota asociada, la cual cumple un rol muy importante en el mantenimiento y composición de la mucosa dérmica, permitiendo un correcto proceso respiratorio y también una barrera contra patógenos. Debido a la situación anterior, se inició un proyecto de investigación cuyo fin es analizar el efecto de la exposición a diferentes tiempos del herbicida a base de glifosato Roundup activo® en la microbiota dérmica de los renacuajos de la Rana Sabanera (D. molitor), exponiendo estos organismos a diferentes tiempos de exposición a Roundup activo® y a partir de muestras dérmicas de estos individuos, se procederá a extraer y purificar el ADN de las muestras, luego con el ADN extraído, se secuenciará el gen 16s ARNr, con el fin de identificar las comunidades microbianas presentes, por medio de la filtración, agrupación y asignación taxonómica de las secuencias obtenidas. Posteriormente, con el fin de analizar las comunidades microbianas, se emplearán evaluaciones para estimar diversidad alfa y beta de las comunidades y a partir de estos análisis, observar si la exposición durante diferentes tiempos a Roundup activo®, tiene un efecto en las comunidades microbianas.
... Amphibians play important roles, such as pest biological control in agricultural systems (Attademo et al., 2005;Khatiwada et al., 2016) and energy flow from aquatic to terrestrial habitats (Sánchez-Hernandez, 2020). Anuran species were found to differ in their sensibility within the field crops (Pyron, 2018). ...
Amphibians find a suitable habitat in rice agroecosystems, but their viability is affected by the sublethal effects of agrochemicals. Animal condition, external morphology, and liver and male gonad tissue histology were examined on Lysapsus limellum and Rhinella bergi, common species that occurs in rice fields (RF) and reference sites (RS) from Santa Fe and Chaco provinces, Argentina, respectively. Animal condition factor showed no significant differences between environments in either species. Males of both species from RF showed asymmetrical testis size. A higher proportion of cysts with early spermatogenesis cell stages were observed in RF specimens than in RS individuals. The proportion of tubules with free spermatozoa differed between environments for L. limellum. Bidder organ presented vacuoles, atretic follicles, and pigmentary cells in R. bergi from Chaco RF. Liver tissues of both species from RF exhibited sinusoid enlargement, hypervascularization, hepatocyte vacuolization, and dilated blood vessels. R. bergi had a higher number of hepatic melanomacrophages in RF than in RS. The histological biomarker was more sensitive than the morphological one to evaluate chronic pesticide exposure using anuran non-target organs (liver, gonads) and Bidder organ. The potential effect of those alterations on the reproductive performance of anurans that commonly occur in agroecosystems needs further research.
... Secondly, the edges of rice fields and associated riparian habitats favor non-pest rodent species as well as amphibian populations that have been documented to provide positive eco-system services in Asian rice cropping systems. 13,92,93 Again, we need to avoid perceptions that associated riparian habitats (e.g., reed beds, irrigation canals, small dams and banks of rice fields) will provide a benefit to rodent populations that cannot be effectively managed. A balanced approach is required. ...
Rodents present a major problem for food security in Asia where smallholder farming families are particularly vulnerable. We review here recent developments in the biology and management of rodent pests in cereal cropping systems in Asia. The past decade has seen a strong focus on ecologically‐based rodent management (EBRM), its adoption in field studies significantly increased rice yields (6‐15%) and income (>15%) in seven Asian countries. EBRM principles also have been successfully applied to maize in China. We provide case studies on EBRM in Cambodia, on interactions between rodent pests and weeds, and on the importance of modified wetlands for biodiversity and rodent pest management. Knowledge on post‐harvest impacts of rodents is increasing. One research gap is the assessment of human health impacts from a reduction of rodent densities in and around houses. We identify ten challenges for the next decade. For example, the need for population modelling, a valuable tool missing from our toolbox to manage rodent pests in cereal systems. We also need to understand better the interactive effects of cropping intensification, conservation agriculture and climate change. Finally, new management approaches such as fertility control are on the horizon and need to be considered in the context of smallholder cereal farming systems and mitigating health risks from zoonotic diseases associated with rodents.
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... In Nepal, the feeding habits of amphibians have been poorly studied (Khatiwada et al., 2016;Sapkota, 2018). Here, we provide an opportunistic record of tadpoles of Polypedates teraiensis (Dubois, 1987) feeding on pumpkin, Cucurbita moschata (Duchesne), based on direct observation. ...
The dietary habits of tadpoles of the Nepalese anurans have not been well studied. Here, we present an opportunistic observation of tadpoles of the Terai tree frog, Polypedates teraiensis feeding on rotten pumpkin (Cucurbita moschata). We suggest further detailed study on the feeding habits of tadpoles in the changing climate in Nepal as they could be used as model organisms to understand their trophic roles and to predict the ecological consequences of their potential loss.
... Indeed, Tucker and Wolcott (1936) claimed that the introduction of cane toads to sugar-cane plantations in Puerto Rico offers "one of the few instances on record of a foreign predator being entirely successful in the control of a native insect pest". The idea also gains support from recent field experiments: by introducing Chinese bullfrogs (Hoplobatrachus rugulosus), Teng et al. (2016) reduced populations of rice leaf rollers, stem borers, and plant hoppers, thereby increasing rice production in paddy-fields by >40% (see also Khatiwada et al., 2016). So, did cane toads really fail to control insect pests in Australia? ...
In 1935, cane toads (Rhinella marina) were brought to Australia to control insect pests. The devastating ecological impacts of that introduction have attracted extensive research, but the toads' impact on their original targets has never been evaluated. Our analyses confirm that sugar production did not increase significantly after the anurans were released, possibly because toads reduced rates of predation on beetle pests by consuming some of the native predators of those beetles (ants), fatally poisoning others (varanid lizards), and increasing abundances of crop‐eating rodents (that can consume toads without ill‐effect). In short, any direct benefit of toads on agricultural production (via consumption of insect pests) likely was outweighed by negative effects that were mediated via the toads' impacts on other taxa. Like the toad's impacts on native wildlife, indirect ecological effects of the invader may have outweighed direct effects of toads on crop production.
... Teng et al. (2016) demonstrated that adding frogs to rice plots significantly reduced the number of rice pests and pathogens, improved soil chemistry, induced shifts in the soil microbiome, and importantly, increased rice yield over fields that contained no frogs. Khatiwada et al. (2016) verified that frogs in rice fields consumed both rice pests and vectors of human disease. Shuman-Goodier et al. (2019) found that a native species of frogs in rice fields in the Philippines ate a predominance of rice pests, although this same study showed that the introduced and invasive cane toad consumed a large number of predators of rice pests, and therefore may have a negative impact on pest management. ...
Rice (Oryza sativa) agriculture provides food and economic security for nearly half of the world's population. Rice agriculture is intensive in both land and agrochemical use. However, rice fields also provide aquatic resources for wildlife, including amphibians. In turn, some species may provide ecosystem services back to the farmers working in the rice agroecosystem. The foundation for understanding the complexity of agroecosystem-human relationships requires garnering information regarding human perceptions and knowledge of the role of biodiversity in these rice agroecosystems. Understanding farmer knowledge and perceptions of the ecosystem services provided by wildlife in their fields, along with their understanding of the risks to wildlife associated with agrochemical exposure, can inform biodiversity preservation efforts. In June and July 2014, we used focus groups and structured and semi-structured interviews that engaged 22 individuals involved in rice agriculture operations in Laguna, Philippines, a village close to the International Rice Research Institute in Los Baños, Philippines, to learn more about farmer perceptions and knowledge of amphibians in their rice fields. We found that many, though not all farm workers (managers, tenants, and laborers) noted declines in amphibian populations over time, expressed how they incorporated frogs and toads (Anura) into their daily lives, and recognized the value of amphibians as ecosystem service providers. Specifically, farmers noted that amphibians provide pest-management through consumption of rice pests, act as biomonitors for pesticide-related health outcomes, and provide a local food and economic resource. Some farmers and farm workers noted the general cultural value of listening to the "frogs sing when it rains." Overall, our findings demonstrate that farmers have an understanding of the value of amphibians in their fields. Future efforts can support how engagement with farmers and farm workers to evaluate the value of wildlife in their fields can lead to directed education efforts to support biodiversity conservation in agroecosystems.
... The value of other predatory species as pest regulators requires further investigation. For example, pest insects form over 50% of the diet of a suite of frog species in the Nepalese rice plantations of Chitwan (Khatiwada et al. 2016) and in southeast China, frog species depredate rice leaf rollers (Cnaphalocrocis medinalis), a problematic species that causes blight. By consuming leaf rollers, frogs increase the number of seedlings and stem width of rice plants (Teng et al. 2016) that may ultimately increase health and crop size for rice farmers. ...
Humanity is exerting unprecendented pressure on natural ecosystems and the species living in them. This pressure is particularly evident among the larger members of the order Carnivora. Their large body size (typically in the 25-600 kg range), life history traits, and reliance on large prey species places them at increased risk of extinction. The International Union for the Conservation of Nature (IUCN) Cat Specialist Group, and the Convention of Migratory Species (CMS) both recognize the deficiencies in robust data available on large carnivores across large tracts of Africa. Furthermore, the population estimates we do have are often drawn from less-reliable methods.
The overarching aim of this PhD thesis was to: 1) use a recently-developed population estimation technique (Elliot and Gopalaswamy 2017) to estimate the densities, population size, and population parameters of large carnivores in the Queen Elizabeth Conservation Area (QECA), Uganda, and use these data to inform their conservation status, 2) improve understanding of the conflict between large carnivores and human communities in Lake Mburo, Uganda, and Mumbai, India, and 3) explore alternative methods to fund conservation measures, including compensation and a wildlife imagery royalty.
In Chapter 1 as part of introducing my thesis, I examined the literature on historic and present methods being used to census African lions Panthera leo and together with a team of international collaborators I made a case for the adoption of spatially explicit capture recapture (SECR) methods for African lions. In Chapter 2 I built upon this and showed the utility of using population state variables (namely movement, sex-ratios, and density) in assessing the conservation status of African lions in a poorly known area of East Africa. I used a population of African lions in south-western Uganda’s Queen Elizabeth Conservation Area (QECA), as a model. I conducted a 93-day African lion census in 2017-2018 and compared the results to those from an intensive radio-collaring study from a decade ago. I hypothesized that if the population of African lions in the QECA was stable or increasing, lion movement distances and home ranges would be similar between the two study periods but if movement distances were larger and sex-ratios were male-biased, the lion population was likely declining. I found male lions expanded their ranges by > 400%, and females >100%, overall lion densities were low (2.70 lions/100 km2, posterior SD=0.47), and the sex ratio of lions in the system was skewed towards males (1 female lion: 2.33 males), suggesting a decline. I concluded this chapter with a discussion of the practical conservation application of using this census technique in other parts of Africa, particularly where historic lion home-range data exist.
In Chapter 3, I used the same spatially explicit capture recapture models on data collected from 74 remote camera traps set across the QECA to assess the population densities of African leopards and spotted hyenas in this savannah park. We surveyed the northern, and southern sections of the QECA, and estimated leopard densities to be 5.03 (range = 2.80–7.63), and 4.31 (range = 1.95–6.88) individuals/100 km2 respectively, while hyena densities were 13.43 and 14 individuals/100 km2. Estimates of hyena density were the highest recorded for the species anywhere within their range using SECR methods. I also suggested that the high hyena densities could be related to the evidence provided in Chapter 2 of African lion decline in the QECA. One hypothesis that could explain the inverse densities of hyenas and lions is that hyenas have experienced competitive release from African lions in the QECA. Similar findings have been reported in the Talek region of Kenya’s Maasai Mara, and Zambia’s Liuwa Plains. This chapter also provided the first SECR population estimates of leopards, and spotted hyenas anywhere in Uganda.
In Chapter 4 and Chapter 5 I addressed the most important threat to the existence of large carnivores: conflict with human communities, and their livestock. While conflict tends to dominate the narrative where large carnivores and humans co-exist, there can often be direct and indirect benefits to humans. In Chapter 4 I examined the ecosystem services provided to people by the Indian leopard Panthera pardus fusca, in Mumbai.The Sanjay Gandhi National Park (SGNP) is located in the city of Mumbai, India, and has some of the highest human population densities in the world. Large carnivores are known to control prey populations, suppress smaller carnivores, reduce parasite load in humans, and promote seed dispersal. However, this chapter is one of the first studies highlighting the ecosystem services provided by a large carnivore outside of a natural or protected system. I showed that leopard predation on stray dogs reduced the number of people bitten by dogs, reduced the risk of rabies transmission, and reduced dog sterilization and management costs. Our estimates showed that dog densities around SGNP (17.3/km2) were 40 times lower than four nearby urban informal settlements (688/km2) and were ten times lower than the citywide mean (160/km2). If it is, as we propose, leopards that are holding the dog population around the park at its current density, dog bites could increase from 3.6 bites/1000 people to 15.5 bites/1,000 people if leopards were to disappear. As over 78% of dog bites in Mumbai require treatment, and 2% require rabies post-exposure vaccination, the treatment costs could reach as high as US$ 200,000 per year (compared to ~US$ 42,500 currently). As development pressures are threatening the region’s leopards, this work shows the potential costs of their local extirpation.
Chapter 5 assesses the landscape-level correlates of livestock attacks by two large carnivores, the spotted hyena, and African leopard in the cattle and sheep/goat farms bordering Lake Mburo National Park, south-western Uganda. I also make suggestions on how to improve the sustainability of a voluntary financial compensation scheme run by a local lodge (the Mihingo Conservation Fund) aimed at alleviating persecution of these species. I used ten years of depredation events to investigate the importance of seasonality and landscape features (ie. terrain ruggedness, proximity to roads, water, human settlements, and vegetation density) on livestock attack probability. I also examined the current costs of the compensation scheme of reported attacks. I showed that most livestock attacks in this region were caused by spotted hyenas, both predators killed at night, did not exhibit seasonal patterns in depredation, and attacks were owed to poorly fortified bomas (82% of leopard attacks and 64% of hyena attacks were made inside bomas). Attacks were also made near human settlements, close to the national park border, and in areas of rugged terrain. The compensation fund made more gross income from tourism activities than was paid in compensation in most years, but compensation costs had to be subsidised by the lodge because the funding was also used in other community development projects (eg. building of a school, and paying children’s school fees).
Chapter 6 of this thesis built upon the sub-theme of Chapter 5, funding of carnivore conservation measures and created a roadmap for a recently proposed idea of a threatened wildlife imagery royalty to stem the large budgetary shortfalls facing large carnivore conservation. The idea of a threatened species imagery royalty was proposed in two recent papers, Good et al. (2017) and Courchamp et al. (2018). I built upon these and discussed how such a royalty could be implemented, explored several legal avenues for its application, and also showed its potential scale in leveraging funding. The creation of a national law which charges a royalty from corporations using the imagery of their threatened wildlife, and a “Fairtrade” equivalent held the most promise for the development of a wildlife imagery royalty. Indeed, articles 3 and 6 of the Convention on Biological Diversity (CBD) encourage sovereign states to ensure activities within their jurisdiction and control do not damage the environment of other states. Similarly they are encouraged to develop national strategies, plans or programs for the conservation and sustainable use of biological diversity. The funding that could potentially be leveraged from a wildlife imagery royalty is immense. I used large felids as a model group to show that the relevant 14 companies on the Forbes 2000 list alone could generate US$ 202 million–2.02 billion if they paid 0.1-1% of their profits in royalties.
My thesis addressed an important but often overlooked component of estimating large carnivore populations, the use of population state variables in informing conservation status. The use of animal movement, sex-ratio, and density information has wide application that transcends large carnivores. My assessment of leopard-dog interactions, and the potential implications for humans, was one of the first examples in the literature of the potential benefits a large carnivore may have to humans. The assessments of compensation and wildlife imagery royalties have important consequences on better managing and also leveraging funding for the conservation of large carnivores and other threatened, enigmatic species.
... The stomach contents of each individual were collected in October in 2016. Prey items were subsequently placed in a Petri dish and identified under a stereoscopic microscope, and reference slides were from wings, antenna and legs (Khatiwada et al., 2016). All prey items were then identified to the lowest possible taxonomic level. ...
... Land fragmentation has multiple negative impacts such as it reduce the scope for irrigation, questions practice in soil conservation, and there by affect productivity and efficiency. In this scenario, the only alternative to increase food security is intensification of production on available land and its proper use (Khatiwada et al., 2016). ...
This paper reviews the agricultural land use pattern of Nepal based on published information. Agricultural land use in Nepal is closely related with the United Nations Sustainable Development Goal Two, which deals with the food security. To meet the increasing food demand, the ecological belts; Terai, and Hills should have a sustainable agricultural production system. However, land fragmentation is high in rapidly urbanizing Terai whereas increasing fallow land and landlord absenteeism is widely prevalent in Hills; both of these scenarios has brought changes in land use pattern for agricultural crops. Under this context, this paper attempts to discuss the changes in major crops grown areas in different time periods and their consequences along with factors responsible for such changes. Multiple factors such as-migration, real-estate business, and an increment in land use for off-farm activities are thought to be responsible for such change in the cropping area. On the other hand, increase in production of major crops has its low level of impact to the progress in food security which is rather related to the swelled purchasing capacity of food through remittance. To address the inefficient land use and low crop production issue, Government of Nepal has endorsed the Land Use Act, 2019 whereas its proper implementation at field level is quite important. Since, poor land management practices have significantly affected soil quality and crop production, urgent steps are needed to reverse the trends in land degradation while maintaining productivity of land through sustainable land management approaches.
... Besides invertebrates, vertebrates can assume an important role in the biological control of several of the target pests. Frogs, fish and ducks can consume large numbers of rice pests, including planthoppers (Khatiwada et al. 2016;Zou et al. 2017;Sheng-miao et al. 2004); for WCR and wireworms, birds act as key predators and can suppress field populations (Bollinger and Caslick 1985;Sheng-miao et al. 2004) and rodents possibly engage in larval predation . A phase-out of neonicotinoid use is key to safeguard and fully exploit these vertebrate-mediated pest control services (e.g., (Humann-Guilleminot et al. 2019b). ...
We present a synthetic review and expert consultation that assesses the actual risks posed by arthropod pests in four major crops, identifies targets for integrated pest management (IPM) in terms of cultivated land needing pest control and gauges the implementation “readiness” of non-chemical alternatives. Our assessment focuses on the world’s primary target pests for neonicotinoid-based management: western corn rootworm (WCR, Diabrotica virgifera virgifera) in maize; wireworms (Agriotes spp.) in maize and winter wheat; bird cherry-oat aphid (Rhopalosiphum padi) in winter wheat; brown planthopper (BPH, Nilaparvata lugens) in rice; cotton aphid (Aphis gossypii) and silver-leaf whitefly (SLW, Bemisia tabaci) in cotton. First, we queried scientific literature databases and consulted experts from different countries in Europe, North America, and Asia about available IPM tools for each crop-pest system. Next, using an online survey, we quantitatively assessed the economic relevance of target pests by compiling country-level records of crop damage, yield impacts, extent of insecticide usage, and “readiness” status of various pest management alternatives (i.e., research, plot-scale validation, grower-uptake). Biological control received considerable scientific attention, while agronomic strategies (e.g., crop rotation), insurance schemes, decision support systems (DSS), and innovative pesticide application modes were listed as key alternatives. Our study identifies opportunities to advance applied research, IPM technology validation, and grower education to halt or drastically reduce our over-reliance on systemic insecticides globally.
... America (Duré et al., 2008), and in some countries, such as Nepal, as many as 13 different species have been recorded (Khatiwada et al., 2016). In Los Baños, Philippines, the location of this study, we documented seven species of amphibians that were abundant within lowland irrigated rice fields. ...
Irrigated rice cropping systems serve the dual role of providing an essential food crop to the world’s most populous regions and functioning as man-made wetlands that harbor wildlife. Amphibians utilize irrigated rice fields throughout multiple life history stages to develop, forage and reproduce. However, routine exposure to pesticides can negatively affect amphibians and the ecosystem services they provide. My dissertation addresses this concern by examining how pesticide exposure affects amphibians that occupy rice fields at multiple scales, spanning physiology, behavior, and ecology. Through a series of experiments and surveys, I also explore the ecosystem services of rice field amphibians as indicators of endocrine disruption and providers of natural pest control. First, I conducted a quantitative meta-analysis where I found that across 39 papers and 23 different chemicals, sub-lethal pesticide exposure consistently affects critical behaviors (swimming speed and activity level) of aquatic vertebrates. Next, I conducted a series of three experiments to test whether exposure to butachlor, one of the most popular herbicides used in rice, affects development, behavior, and competitive interactions between a native and invasive species. My results provide evidence that environmentally relevant concentrations of butachlor disrupt thyroid hormone mediated development, and demonstrates that important species interactions such as competition can be affected by pesticide exposure in aquatic ecosystems. Last, I examined the diet composition of native Luzon wart frogs and invasive cane toads over two seasons, and found that the native frog may provide effective pest control services and thereby reduce the need for insecticide use, but that non-native cane toads may indirectly damage rice crops by consuming a disproportionate number of beneficial predators. Taken together, this research provides evidence to encourage sustainable management of rice that prioritizes reducing pesticide inputs and promoting native species, such as the Luzon wart frog, in order to safeguard biodiversity while simultaneously improving yields.
... These animals are considered as farmers' friends, as they control various pests such as rodents and insects. A recent study from lowland Nepal highlighted that frogs are potential biological control agents and thus an integral part of the rice paddy system (Khatiwada et al., 2016). ...
Conversion of natural habitat into agricultural landscape has been identified as one of the major drivers of habitat loss. Human-modified ecosystems, such as agricultural land, have gained significant attention in terms of the conservation of their native biodiversity. We studied the effectiveness of organic agroecosystems in conserving odonate diversity by comparing organic terrace rice cultivation with a nearby natural forest system with streams in Sikkim, Eastern Himalaya, India. We sampled adult odonates using a transect count method (laying six permanent transects) covering two villages (Lingmoo in South Sikkim and Dzongu in North Sikkim), making a total of 48 transect counts. A total of 881 individual odonates representing 31 species under two suborders (16 Anisoptera and 15 Zygoptera) and seven families were recorded during this study. Of these, 20 species representing three families and 18 species representing seven families were observed in terrace rice cultivation and the natural forest system, respectively. Beta diversity estimates showed that the community composition of the odonates differed qualitatively (incidence measure) and quantitatively (abundance measure) between the two land use types. Turnover component (abundance balance in case of abundance based beta diversity measure) had higher contribution in the overall beta diversity, suggesting that one assemblage of species is being replaced by another due to environmental sorting. The variation in community composition between the two habitats was statistically significant. Our results suggest that organic wetland habitats are important for conservation of odonates and associated biodiversity (especially herpetofauna) in the Himalaya and require urgent conservation attention.
... to September in 2015 and 2016 in eastern and central Nepal (Figure 1). Multiple survey methods were used; for example, visual encounter surveys, acoustic surveys, and leaf litter searches were made during the night (1900h-0000h) as described by Khatiwada et al., (2016) and Khatiwada et al., (2019). Specimens were collected by hand, euthanized using 20% Benzocaine gel, tissue samples were collected, and specimens later fixed in 4% formalin for 24 h and then preserved in 70% ethanol. ...
This study investigated the systematics of the megophryid genus Scutiger from eastern and western Nepal using molecular and morphological data. Our results support two divergent lineages, one of which has nuptial spines on the dorsal surface of the first three fingers while the other has spines only on the dorsal surface of the first two fingers.
The Ghunsa lineage from eastern Nepal shows significant morphological and molecular differences to other species of genus Scutiger and is here described as a new species. Based on the molecular analysis, the Muktinath lineage from western Nepal is confirmed to be Scutiger boulengeri and represents a species complex widespread throughout the Himalayan region. The newly described taxon is endemic to the eastern Himalayas and currently known only from the Ghunsa valley, Taplejung district, Nepal .
... In general, amphibians can be used as bioindicators of ecosystem quality, or at least of the niche they occupy (Attademo et al. 2007;2014;Echegaray and Hernando 2003;Peltzer et al. 2006). These organisms have also been used as biological control agents in agricultural systems (Khatiwada et al. 2016). ...
Diversity of Anurans in Rice Fields under Organic and
Conventional Management in Santa Fe Province, Argentina
... This large bodied frog (up to 160 mm) has high reproductive potential (up to 5,750 eggs per clutch; Oliveira et al., 2017) and is uncommon or absent in forested and coastal regions but occurs as a human commensal in plantations and agricultural fields (Daniels, 2005). It is considered a dietary generalist, feeding on invertebrates and even large anurans such as Duttaphrynus melanostictus (Padhye et al., 2008;Datta & Khaledin, 2017); however, quantitative diet assessment with adequate sample size across habitats and seasons is lacking (but see Khatiwada et al., 2016 for diet of H. tigerinus in rice fields of Nepal). ...
Amphibian invasions have considerable detrimental impacts on recipient ecosystems. However, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We carried out diet analyses of the invasive H.Tigerinus and native anurans, across four habitat types and two seasons; we hypothesized that (i) small vertebrates constitute a majority of the H.Tigerinus diet, particularly by volume and (ii) the diet of H.Tigerinus significantly overlaps with the diet of native anurans, thereby, leading to potential competition. We assessed the diet of the invasive H.Tigerinus (n = 358), and individuals of the genera Limnonectes (n=375) and Fejervarya (n=65) and found a significant dietary overlap of H.Tigerinus with only Limnonectes. Small vertebrates, including several endemic species, constituted the majority of H.Tigerinus, diet by volume, suggesting potential impact by predation. Prey consumption and electivity of the three anurans indicated a positive relationship between predator-prey body sizes. Individuals of H.Tigerinus and Fejervarya chose evasive prey, suggesting that these two taxa are mostly ambush predators; individuals of Limnonectes chose a mixture of sedentary and evasive prey indicating that the species employs a combination of active search' and 'sit and wait' foraging strategies. All three species of anurans mostly consumed terrestrial prey. This intensive study on a genus of newly invasive amphibian contributes to knowledge of the impact of amphibian invasions, and elucidates the feeding ecology of H.Tigerinus, and species of the genera Limnonectes and Fejervarya. We also stress the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians.
... Amphibians utilize rice fields throughout larval, metamorphic, and adult life stages, and provide important ecosystem services. They consume arthropod pests (Attademo et al. 2005;Khatiwada et al. 2016), act as sentinels to reveal negative impacts of pesticide exposure, and are a staple food source for humans (Punhali 1995;Hocking and Babbitt 2014). ...
Springer Link: http://rdcu.be/v4zj
Increased pesticide use in rice agricultural ecosystems may alter competitive interactions between invasive and native amphibian species. We conducted an experiment with two rice paddy amphibians found in Luzon, Philippines, the invasive cane toad (Rhinella marina) and the endemic Luzon wart frog (Fejervarya vittigera), to determine whether exposure to a common herbicide, butachlor, drives competitive interactions in favor of the invasive amphibian. Our results revealed that competition had a strong effect on the development of both species, but in opposing directions; Luzon wart frog tadpoles were smaller and developed slower than when raised alone, whereas cane toad tadpoles were larger and developed faster. Contrary to our predictions, development and survival of endemic wart frog tadpoles was not affected by butachlor, whereas invasive cane toad tadpoles were affected across several endpoints including gene expression, body size, and survival. We also observed an interaction between pesticide exposure and competition for the cane toad, where survival declined but body size and expression of thyroid sensitive genes increased. Taken together, our findings indicate that the success of the cane toad larvae in rice fields may be best explained by increased rates of development and larger body sizes of tadpoles in response to competition with native Luzon wart frog tadpoles rather than lower sensitivity to a common pesticide. Our results for the cane toad also provide evidence that butachlor can disrupt thyroid hormone mediated development in amphibians, and further demonstrate that important species interactions such as competition can be affected by pesticide exposure in aquatic ecosystems.
... Ostracods have been reported to prey on amphibian eggs and tadpoles, which most animals find unpalatable (Gray et al., 2010;Ottonello and Romano, 2011). This could potentially be another way ostracods affect the rice field environment, as amphibians act as biological controls on rice pests (Khatiwada et al., 2016). ...
p class="Standard">Ostracods are very common in rice fields and they can have a significant influence on the rice field ecosystem. They can reach very high densities, often higher than other meiofauna, and their activities can have both positive and negative effects on rice harvests. They directly affect nutrient recycling through excretion, and indirectly by physically disturbing the soil and releasing minerals, thus improving rice growth. On the other hand, ostracods grazing on nitrogen-fixing cyanobacteria potentially reduce rice yields. Rice is a primary staple food for over half of the world’s population, and therefore ostracods can have a significant impact on human food supply. The origin of the rice field ostracod fauna is poorly known, but many rice field ostracods are considered invasive, especially in southern Europe, and from rice fields they have the potential to spread to surrounding natural habitats. Despite their invasive potential and ecological effects on the rice field ecosystem, very little is known about the diversity, ecology and impacts of rice field ostracods in many rice-producing countries. One hundred and ninety-two named ostracod species/subspecies have been reported from rice fields in 26 countries and states worldwide in the published literature; for over three-quarters of rice-producing countries, no data are readily available, and for most of the countries that have available data, diversity is clearly under-reported. Most species that have been documented from rice fields belong to the Cyprididae (78%), a family that makes up approximately 43% of the 2500+ non-marine ostracod species. A further six families (Candonidae, Darwinulidae, Entocytheridae, Ilyocyprididae, Limnocytheridae and Notodromadidae) form the remainder of rice field ostracods. Twenty-two percent of the species reported from rice fields are sexually reproducing, 18% have mixed reproduction, but are mostly asexual, and for 60% males are unknown, and are probably entirely asexually reproducing species. This review and checklist of rice field ostracods are presented to facilitate further research on this group in rice field habitats, research that is crucial for food security in many regions.</p
... Therefore, institutions such as World Health Organization are now focusing on development of advanced diagnostic tests, drugs, and vaccines [69]. An increase of the use of advanced molecular technologies [87,88] and studies on biological control methods such as use of microorganisms, frogs, mites, and spiders as biological control agents can be seen in the recent past [94,95]. ...
The present works reviewed the existing information on leishmaniasis in Sri Lanka and in other countries, focusing on challenges of controlling leishmaniasis in the country, in an outbreak. Evidence from recent studies suggests that there is a possibility of a leishmaniasis outbreak in Sri Lanka in the near future. Difficulty of early diagnosis due to lack of awareness and unavailability or inadequacy of sensitive tests are two of the main challenges for effective case management. Furthermore, the absence of a proper drug for treatment and lack of knowledge about vector biology, distribution, taxonomy and bionomics, and reservoir hosts make the problem serious. The evident potential for visceralization in the cutaneous variant of L. donovani in Sri Lanka may also complicate the issue. Lack of knowledge among local communities also reduces the effectiveness of vector and reservoir host control programs. Immediate actions need to be taken in order to increase scientific knowledge about the disease and a higher effectiveness of the patient management and control programs must be achieved through increased awareness about the disease among general public and active participation of local community in control activities.
... Three (VDCs) namely Bachhauli, Ghyalchok, and Ghanapokhra from the Chitwan, Gorkha, and Lamjung districts, respectively, were selected for the case study ( Figure 2). The study areas stretch from 190 to 2700 m above sea level (hereafter m) and from the sub-tropical to cool temperate climatic zone representing three different agroecological regions (inner terai, mid hill, and high hill) of Nepal [39,40]. Smallholder subsistence farming with a mixed crop-livestock production system is a common source of livelihood, but the level of agricultural dependency and its importance to overall household income varies across the area. ...
Understanding household livelihood strategies is pivotal to minimize rural poverty in the least developed countries like Nepal. This study is an attempt to assess livelihood strategies pursued by rural households, investigate the most remunerative strategy, and identify the factors that influence a household's choice of better strategies in rural Nepal. Primary data collected in 453 households from three villages of central Nepal are analyzed quantitatively within a sustainable livelihood framework. This study categorized households into five main livelihood strategy groups. The results showed that the majority (61%) of the households diversified their income to non-farm sources. Livelihood diversification to business/enterprise strategies adopted by 16% of the households is the most remunerative strategy followed by commercial farming that includes 13% of the sample and are more relevant to poverty reduction. Land holding, education, agriculture and skill training, access to credit, and proximity to the road and market center are the major influencing factors on the adoption of higher returning livelihood strategies. Stimulating poor households to follow market-oriented farm and non-farm activities by improving access to education, vocational training, rural credit, and rural infrastructures is momentous for reducing poverty in the rural areas of central Nepal.
The wildlife that inhabits natural wetlands has been threatened in recent years because of human activities, such as land use changes. Rice fields, however, have been receiving attention as possible substitutes for natural wetlands. Amphibians are one of the representative taxa that inhabit rice fields and are critical for their food webs and ecosystem maintenance. This study was conducted to understand the community characteristics of anuran species living in the rice fields in the mid-western region of the Republic of Korea, in accordance with their habitat characteristics. The distribution and abundance of each of the Anura species identified in 40 rice fields was examined, from March to October in 2016 and 2017. Similar anuran communities were patternized using a self-organizing map (SOM). Furthermore, this study analyzed the relationships between the patternized anuran communities and environmental variables (landscape, atmospheric, physical, and aquatic) using random forest analysis. Key indicator species were also identified to understand the environmental characteristics of each SOM group. The results of this study showed that the anuran species that were assessed could be classified into four clusters using the SOM, and each cluster reflected a breeding season. Moreover, they also reflected the relationship between the indicator species of each cluster and the environmental variables. Clusters 1 and 4 represented summer, and the number of species, species diversity, and species richness were all high in these two clusters. Landscape variables, such as the forest or rice field area, were important for the species belonging to these two clusters. There were four indicator species in Cluster 1, the black-spotted frog, Wrinkled frog, American bullfrog, and Japanese tree frog, and they preferred high altitudes and large forested areas. However, the two indicator species of Cluster 4, the Gold-spotted pond frog and Suweon tree frog, which are endangered in the Republic of Korea, favored low altitude and large rice field areas. Various anuran species, including the endangered species, densely inhabit the rice fields in the mid-western region of the Republic of Korea, and the relationship between the patterning of anuran communities and environmental variables was identified in this study. This information will be valuable for the future conservation and management of amphibian species in the Republic of Korea.
Identifying the adverse impacts of pesticide exposure is essential to guide regulations that are protective of wildlife and human health. Within rice ecosystems, amphibians are valuable indicators because pesticide applications coincide with sensitive reproductive and developmental life stages. We conducted two experiments using wild cane toads (Rhinella marina) to test 1) whether environmentally relevant exposure to a commercial formulation of butachlor, an acetanilide herbicide used extensively in rice, affects amphibian development and 2) whether cane toad tadpoles are capable of acclimatizing to sub-lethal exposure. First, we exposed wild cane toads to 0.002, 0.02, or 0.2 mg/L of butachlor (Machete EC), during distinct development stages (as eggs and hatchlings, as tadpoles, or continuously) for 12 days. Next, we exposed a subset of animals from the first experiment to a second, lethal concentration and examined survivorship. We found that cane toads exposed to butachlor developed slower and weighed less than controls, and that development of the thyroid gland was affected: exposed individuals had smaller thyroid glands and thyrocyte cells, and more individual follicles. Analyses of the transcriptome revealed that butachlor exposure resulted in downregulation of transcripts related to metabolic processes, anatomic structure development, immune system function, and response to stress. Last, we observed evidence of acclimatization, where animals exposed to butachlor early in life performed better than naïve animals during a second exposure. Our findings indicate that the commercial formulation of butachlor, Machete EC, causes thyroid endocrine disruption in vertebrates, and suggest that exposure in lowland irrigated rice fields presents a concern for wildlife and human health. Furthermore, we establish that developmental assays with cane toads can be used to screen for adverse effects of pesticides in rice fields.
Predators and scavengers are frequently persecuted for their negative effects on property, livestock and human life. Research has shown that these species play important regulatory roles in intact ecosystems including regulating herbivore and mesopredator populations that in turn affect floral, soil and hydrological systems. Yet predators and scavengers receive surprisingly little recognition for their benefits to humans in the landscapes they share. We review these benefits, highlighting the most recent studies that have documented their positive effects across a range of environments. Indeed, the benefits of predators and scavengers can be far reaching, affecting human health and well-being through disease mitigation, agricultural production and waste-disposal services. As many predators and scavengers are in a state of rapid decline, we argue that researchers must work in concert with the media, managers and policymakers to highlight benefits of these species and the need to ensure their long-term conservation. Furthermore, instead of assessing the costs of predators and scavengers only in economic terms, it is critical to recognize their beneficial contributions to human health and well-being. Given the ever-expanding human footprint, it is essential that we construct conservation solutions that allow a wide variety of species to persist in shared landscapes. Identifying, evaluating and communicating the benefits provided by species that are often considered problem animals is an important step for establishing tolerance in these shared spaces.
The presence of the recently introduced primary dengue virus vector mosquito Aedes aegypti in Nepal, in association with the likely indigenous secondary vector Aedes albopictus, raises public health concerns. Chikungunya fever cases have also been reported in Nepal, and the virus causing this disease is also transmitted by these mosquito species. Here we report the results of a study on the risk factors for the presence of chikungunya and dengue virus vectors, their elevational ceiling of distribution, and climatic determinants of their abundance in central Nepal.
The major insect pests of rice crop encountered in northeastern part of the Uttar Pradesh are:(a) Root feeders such as termites, mole cricket, rice root weevil and rice water weevil; (b) Stem borers that include yellow stem borer [Scirpophaga incertulas (Walker)], white stem borer [Scirpophaga innotata (Walker)], striped stem borer [Chilo suppressalis (Walker)], dark headed stem borer [Chilo polychrysus (Meyrick)], pink stem borer [Sesamia inferens (Walker)], (c) Leafhoppers and plant hoppers such as : white rice leafhopper (Cofana spectra Distant), brown planthopper (Nilaparvata lugens Stal), whitebacked planthopper [Sogatella furcifera (Horvath)].the green planthopper [Nephotettix nigropictus (Stat.)], Nephotettix virescens (Distant), leafhopper (Pyrilla perpusilla Walker), (d) Defoliators such as swarming caterpillar or armyworm [Spodoptera mauritia (Boisduval)], oriental armyworm [Mythimna separata (Walker)], rice grasshopper [Hieroglyphus banian (Fabr.)], (e) Grain suckers such as rice earhead bug (Leptocorisa acuta Thunberg), and (f) other pests such as rice gall midge [Orseolia oryzae (Wood-Mason)], the rice leaf folders [Cnaphalocrocis medinalis (Guenee), Marasmia patnalis Bradley, Marasmia
exigua (Butler)], the grain aphid [Hysteroneura setariae (Thomas)], pentatomid bug [Nezara viridula (Linn.)], rice mealy bug [Brevennia rehi (Lind.)], rice hispa [Dicladispa armigera (Oliver)], rice thrips [Stenchaetothrips biformis (Bagnall)], rice caseworm [Nymphula depunctalis (Guenee)], whorl maggot flies [Hydrellia philippina Ferino], zigzag leafhopper [Recilia (Inazuma) dorsalis (Motschulsky)] and the common cutworm [Spodoptera litura (Fabricius)].
The cultivation of tropical Asian rice, which may have originated 9000 yr ago, represents an agricultural ecosystem of unrivaled ecological complexity. We undertook a study of the community ecology of irrigated tropical rice fields on Java, Indonesia, as a supporting study for the Indonesian National Integrated Pest Management Programme, whose purpose is to train farmers to be better agronomists and to employ the principles of integrated pest management (IPM). Two of our study objectives, reported on here, were (1) to explore whether there exist general and consistent patterns of arthropod community dynamics related to natural or intrinsic levels of biological control, and (2) to understand how the existing levels of biological control are affected by insecticide use, as well as by large-scale habitat factors relating to differing patterns for vegetational landscapes, planting times, and the length of dry fallow periods. We performed a series of observational studies and two experimental studies. Abundant and well-distributed populations of generalist predators can be found in most early-season tropical rice fields. We took samples from plants and water surface using a vacuum-suction device, and from the subsurface using a dip net. Our results show that high populations of generalist predators are likely to be supported, in the early season, by feeding on abundant populations of detritus feeding and plankton-feeding insects, whose populations consistently peak and decline in the first third of the season. We hypothesize that since this abundance of alternative prey gives the predator populations a "head start" on later-developing pest populations, this process should strongly suppress pest populations and generally lend stability to rice ecosystems by decoupling predator populations from a strict dependence on herbivore populations. We experimentally tested our hypothesis of trophic linkages among organic matter, detritivores and plankton feeders, and generalist predators and showed that by increasing organic matter in test plots we could boost populations of detritivores and plankton-feeders, and in turn significantly boost the abundance of generalist predators. These results hold for populations found on the plant, on the water surface, and below the water surface. We also demonstrated the link between early season natural enemy populations and later-season pest populations by experimentally reducing early-season predator populations with insecticide applications, causing pest populations to resurge later in the season. Overall, these results demonstrate the existence of a mechanism in tropical irrigated rice systems that supports high levels of natural biological control. This mechanism depends on season long successional processes and interactions among a wide array of species, many of which have hitherto been ignored as important elements in a rice ecosystem. Our results support a management strategy that promotes the conservation of existing natural biological control through a major reduction in insecticide use, and the corresponding increase in habitat heterogeneity. detritivores and plankton feeders; field experiment; green revolution; insecticide use and pest outbreaks; integrated pest management; Java, Indonesia; rice-field ecology; rice landscape patterns; synchronous vs. nonsynchronous plantings.
Mosquito eggs survive drought conditions while harboring pathogens, perpetuating diseases through seasons. Biological control of mosquitoes using vertebrates mostly highlights the role of larvivorous fish. Here we show that tadpoles with different life-history characteristics predate on Aedes aegypti (vector mosquito of Dengue virus) eggs. We did four experiments involving tadpoles of Polypedates cruciger to determine: i. egg laying preference of female mosquitoes, in normal water, water in which tadpoles were previously present, and water in which tadpoles were present at the time of experiment; ii. survivability of mosquito eggs in tanks in presence vs. absence of tadpoles; iii. egg predation through direct observation (video-recording) and gut content analysis; iv. if egg predation is prevalent among different species of tadpoles of four species of randomly selected genera, Bufo, Ramanella, Euphlyctis and Hoplobatrachus were subjected to experiment iii only. We show that mosquitoes have a preference to lay eggs in tadpole water and that tadpoles destroy such eggs laid. Direct observations substantiate that all tadpole species tested are mosquito egg predators. With about seven thousand frog species worldwide, living in a diversity of aquatic habitats where fish cannot reach, the role of tadpoles in biological control of mosquitoes can be significant than currently understood.
Although Brazil encompasses one of the most abundant anuran faunas in the world, quantitative information on anuran ecology and diet are limited, especially in the Northeastern region. We analyzed the diet of six species: Hyla albomarginata, Hyla cf. branneri, Hyla minuta, Phyllomedusa aff. hypochondrialis (Hylidae), Leptodactylus natalensis, and Physalaemus cuvieri (Leptodactylidae) in a temporary pond in a rainforest remnant in Pernambuco, between 1999-2000. We analyzed diet composition, degree of food preference, and seasonal variations in diet. Leptodactylus natalensis and P. cuvieri showed higher diet diversity, whereas H. minuta consumed fewer food items. Insecta, Arachnida, and plants were preferential items for most species. Acari were consumed by all species; Hymenoptera, Odonata, and Coleoptera were also often consumed. A slight increase in diet diversity occurred in the rainy season. The species showed a generalist feeding behaviour, although P. cuvieri consumed Formicidae as major prey item.
Orthopteran fauna in rice ecosystem at Coimbatore were surveyed in the Paddy Breeding Station and Wetlands of Tamil Nadu Agricultural University since 1997. Fifty species of Orthoptera (8 long-homed grasshoppers, 28 short-horned grasshoppers, 3 crickets, 1 tree cricket and 10 pygmy grasshoppers) were recorded in the survey. Those collected from the rice fields were found feeding on rice foliage and grains and a few of the Orthopterans viz., Anaxipha longipennis (Serv.), Metioche vittaticollis (Stal), Metioche bicolor (Stal.) (Trigonidiidae) collected mainly from the bunds were observed to be predators of rice insect pests.
A clear understanding of the relationships between overlapping, similarity, and competition is necessary to understand many of the questions about the structure and operation of a community. Rhinella icterica (Spix, 1824) and Rhinella crucifer (Wied Neuwied, 1821) are sympatric species of toads occurring in the National Park of Serra dos Órgãos in southeastern Brazil. The aim of the present study was to assess the dietary overlap of these two species. Ninety-four stomachs were analyzed, and 2245 prey items were found. Common prey were Hymenoptera, Coleoptera, Diptera, Lepidoptera larvae, Blattaria, Orthoptera, Hemiptera, Opiliones, and Aranaea. Ants were the most important prey in both diets, followed by beetles and cockroaches. The niche breadth of R. icterica was 1.76 and of R. crucifer was 1.28. The dietary overlap between the species was 98.62%. A positive correlation was observed between jaw width and prey size consumed by R. icterica.
In this note we present several previously unpublished cases of Great Grey Shrike, Lanius excubitor, predation in western Poland on adult amphibians, including poisonous toads, and a novel special behaviour skinning toads. We briefly discuss the potential implications of these observations for understanding shrike foraging behaviour and gaps in our current knowledge on bird-toad interactions.
Rice varieties with different levels of resistance were evaluated in the green-house and insectary to determine their effect on populations of brown planthoppers, Nilaparvata lugens. In the absence of predators, N. lugens mortality was highest on the resistant (R), intermediate on the moderately resistant (MR), and lowest on the susceptible (S) varieties. When predators were added to the cages, N. lugens mortality increased on all varieties but was highest on the R varieties. When the effect of varietal resistance on N. lugens mortality was eliminated by using Abbott's formula, predation by the spider, Lycosa pseudoannulata, was highest on the R varieties at a ratio of 20 N. lugens per spider. In a field study, N. lugens populations at 40 days after transplanting were lowest on the R varieties, whereas predator populations were similar on all varieties irrespective of their level of N. lugens resistance. The prey-predator ratio on the R varieties was, thus, most favorable for effective biocontrol. The field test indicated that moderate levels of N. lugens resistance were beneficial when combined with activity of natural enemies because N. lugens populations remained below the economic threshold in the R and MR varieties, whereas the economic threshold was surpassed on the S varieties.
Stomach-flushing is a gentle treatment in analysing the diet of vertebrates. We applied this method in the study of seasonal nutrition of anurans of 15 species at an Araucaria forest habitat on the Serra Geral of Rio Grande do Sul, Brazil. Over 500 frogs and toads of different body size were handled in order to evaluate an improved protocol without narcosis using soft infusion tubes in order to avoid negative effects of the flushing procedure. The specimens were treated soon after capture and then returned to the sampling sites. Our results are discussed with reference to the few studies on stomach flushing in amphibians. The improved technique is recommended to avoid killing of numerous animals for nutritional studies, in particular because of the worldwide threatening of amphibian populations.
We examined dietary habits of the introduced cane toad Bufo marinus at three sites representing different types of habitats (pond, forest, and rice paddy) on Ishigakijima Island, southern Ryukyus, Japan. Stomach contents analysis revealed that the toad mostly utilizes terrestrial arthropods, of which hymenopterans (mostly ants), adult coleopterans, hemipterans, and araneans dominated in the frequency of occurrence, hymenopterans in the numerical proportion, and larval lepidopterans, adult coleopterans, and larval dipterans in the volumetric proportion. Comparisons in taxonomic composition of the toad's stomach contents and pitfall and sweeping net samples suggested ignorance or avoidance of Amphipoda by the toad. Our results suggest the possibility of considerable predation pressure of B. marinus upon the native arthropods, and ants in particular, on Ishigakijima Island.
Biodiversity relevant to pest management of tropical irrigated rice pests is discussed in terms of variation within rice plants, rice fields, groups of rice fields and rice associated ecosystems. It is concluded that, in the unique cropping conditions and stable water supply of tropical irrigated rice, the manipulation of a relatively few manageable components of diversity can confer stability such that pests are mostly kept at levels which do not justify the use of insecticides. The justification for, and supplementary use of, insecticides needs to be radically reassessed. There is no evidence that a natural control-based approach, as recommended in this review, is incompatible with farmer practicability or with future developments in rice production technologoy, except perhaps the possible mechanization-driven increase in field size which would decrease bund area. In contrast, the insecticide-based approach is not only harmful to natural controls but is costly and mostly demands impracticable decision making by farmers on need-based use. -from Authors
The grass cutting programme (GCP) of Royal Chitwan National Park (RCNP) has been very successful in gaining local people's acceptance of RCNP. The GCP is recognized internationally as a model for park-people conflict resolution, but has seemingly become a spent force. The aim of the present study was to assess the extent to which the GCP is a form of ‘community-based conservation’ on the one hand, or ‘nature-based development’ on the other. During the ten days of open access in 1999, almost 50 000 tonnes of biomass were removed from the Park; the total gross economic value of the GCP in 1999 was more than US$ 1 million. Illegal fuelwood was the single most important product extracted from RCNP and accounted for half of the total quantity and economic value of all resources collected. It is argued that the GCP does not, in its present form, comply with the concept of community-based conservation, but is rather an example of nature-based development, where important natural core areas are exploited in the name of development. This study suggests a two-fold approach to reappraise the importance of the GCP in solving park-people conflicts without ignoring nature conservation. Firstly, access should be provided in different areas at different times instead of opening the whole Park at the same time. Secondly, since for the last 10–15 years buffer-zone community forestry has not been able to substitute fuelwood from RCNP, other ways to address local people's energy demand should be considered. It is argued that park-people conflicts in RCNP have not been solved, but only postponed, especially by compromising forest conservation and the possibility of the GCP to supply villagers with essential products in the future.
Recent evidence of the important role of emerging diseases in amphibian population declines makes it increasingly important to understand how environmental changes affect amphibian immune systems.
Temperature‐dependent immunity may be particularly important to amphibian disease dynamics, especially in temperate regions. Changes in temperature are expected to cause deviations away from optimal levels of immunity until the immune system can respond.
To test whether temperature changes cause deviations from optimal immunity under natural conditions, we conducted a seasonal survey of adult Red‐Spotted Newts and measured basal levels of several immunological variables.
We then examined these findings in relation to: (1) the lag hypothesis, which predicts that changes in temperature‐dependent immune parameters lag behind short‐term temperature changes, and (2) the seasonal acclimation hypothesis, which predicts that immune cell production declines during long‐term temperature decreases until amphibians can fully acclimate to winter conditions.
Our results supported both hypotheses, showing a spring lag effect on lymphocyte levels and an even stronger seasonal acclimation effect on lymphocytes, neutrophils and eosinophils in the autumn. Our findings suggest that temperature variability causes increased susceptibility of amphibians to infection, and they have implications for the emergence of disease and the potential for climate change to exacerbate amphibian decline.
Irrigated rice fields are temporary wetland agro-ecosystems, managed with a variable degree of intensity. A survey was carried out in Sri Lanka to document the overall biodiversity associated with this unique agro-ecosystem, using a combination of sampling techniques to document different groups of fauna and flora. The total number of biota recorded and identified from the rice field ecosystem during the entire study period consisted of 494 species of invertebrates belonging to 10 phyla and 103 species of vertebrates, while the flora included 89 species of macrophytes, 39 genera of microphytes and 3 species of macrofungi. Of the total species documented, 15 species of invertebrates and one weed species are new records to Sri Lanka. Arthropods were the dominant group of invertebrates (405 species), of which 55 species were rice pest insects, and 200 species were natural enemies of pest insects. The fauna and flora recorded from the rice field were observed to follow a uniform pattern of seasonal colonization and succession during successive rice cultivation cycles. The biodiversity of the irrigated rice agro-ecosystem interests both agroecologists and conservation biologists. Therefore, the integrated efforts of these two groups can result in the formulation of strategies based on biodiversity as an organizing principal in the sustainable management of the rice field agro-ecosystem.
Studies on the relationship between habitat heterogeneity and animal abundance are essential for understanding what determines
biodiversity. Transect-based direct observations of eight principal prey species of tiger in the Chitwan National Park (CNP)
were used to determine their abundances and habitat preferences. Chital was the most abundant prey species of tiger (Panthera tigris). Each of the prey species had significantly different habitat preferences except sambar deer and chital. Habitat preference
was measured using Manly’s preference index, which revealed that short grassland, mixed forest, and riverine forest were the
most preferred habitats of the prey species. The results indicate that large species of deer tend to be found in more diverse
habitats than small species, except muntjac. The abundance of the principal prey species of tiger was positively correlated
with habitat heterogeneity. The habitat, which contributes significantly to the heterogeneity of the landscape, is grassland
in large patches of forest. The ongoing increase of forest cover in the CNP has led to a reduction in the area of grassland,
which may negatively affect the abundance of the prey species of tiger. Hence, it is suggested that the restoration of landscape
heterogeneity is the best way to manage the habitats in the CNP.
KeywordsUngulates–Prey–Heterogeneity–Habitat selection–Abundance–Preference–Resource selection
A questionnaire survey of 408 households explored the role of socio-economic and cultural factors in rice (Oryza sativa L.) varietal diversity management on-farm in two contrasting eco-sites in Nepal. Multiple regression outputs suggest that
number of parcels of land, livestock number, number of rice ecosystems, agro-ecology (altitude), and use of chemical fertilizer
have a significant positive influence on landrace diversity on-farm, while membership in farmers’ groups linked to extension
services has significant but negative influence on landrace diversity. Factors with significant positive influence on diversity
of modern varieties on-farm were number of parcels of land and of rice ecosystems, access to irrigation, membership in farmers’
groups, and use of insecticide. Within communities, resource-endowed households maintain significantly higher varietal diversity
on-farm than resource-poor households and play a significant role in conserving landraces that are vulnerable to genetic erosion
and those with socio-cultural and market-preferred traits. Resource-poor households also contribute to local diversity conservation
but at lower richness and area coverage levels than resource-endowed households. Households where a female had assumed the
role of head of household due to death or migrant work of her husband had less diversity due to lower labor availability.
Landraces with socio-cultural and market-preferred traits are few in number but have potential to be conserved on-farm.
Rice field expansion is one of the activities associated with the disappearance of 90% of the wetlands in southern Brazil. Worldwide, rice agriculture has been recognized as having considerable potential value for many aquatic species. Nevertheless, management practices in such systems must be ameliorated and better investigated.
This study evaluated the potential role of rice fields as refugia for amphibians, and whether different hydrologic management practices after rice cultivation could contribute to wetland amphibian conservation in southern Brazil.
Six collections were made in six rice fields with different management practices after cultivation (three dry and three flooded) and three natural wetlands. The amphibians were sampled through six random 15‐min visual transects per collection in each rice field and the natural wetlands.
In total, 2139 anuran individuals were observed in rice fields (798) and Reserva Lake (1341), comprising 12 anuran species distributed among five anuran families. Anuran richness and abundance varied over the rice cultivating cycle, and they were higher in the growing phases than in the fallow phases. The mean anuran richness and abundance was higher in Reserva Lake than in flooded and dry rice fields.
The different management practices adopted after the harvesting period (presence or lack of surface water) did not influence the anuran richness and abundance. It did, however, influence species composition.
The difference in species composition between the management practices adopted is an interesting result in terms of biodiversity conservation. Rice producers could maintain part of their agricultural land flooded during the fallow phase as a strategy to preserve a higher diversity of anurans. These results should be taken into consideration in wetland conservation plans in southern Brazil; however, the percentage of each agricultural land that should be kept flooded should be decided by Brazilian agricultural and conservation policies. Such a strategy would reconcile agricultural/economic needs with the conservation of biodiversity in southern Brazil, where more than 90% of wetland systems have already been lost. Copyright © 2009 John Wiley & Sons, Ltd.
Artificial ponds or irrigated systems scattered throughout farmlands can offer important habitats for anurans and can be interesting sites for research on species resources use in a changing landscape. This study describes the diet and resource partitioning among anurans inhabiting irrigated rice fields in the Pantanal region. Twenty categories of prey were found in the stomachs of Leptodactylus chaquensis, L. elenae, L. podicipinus and Rhinella bergi, the most frequent being Coleoptera, Hymenoptera, larvae of Hexapoda, Hemiptera, Diptera and Orthoptera. The great differences found in the diet of these species in rice fields compared to other locations, according to available records in the literature, was the increased importance of Hemipitera and Orthoptera and the decrease in importance of Hymenoptera in the diet of leptodactylids. These differences might be attributed to changes in the availability of resources in response to habitat modification. Although diet composition was very similar among species, niche overlap was larger than expected by chance, suggesting that the competition for food resources is not, or has not been, a significant force in determining the structure of this frog community. Two non-exclusive hypotheses could be considered as a justification for this result: 1) the high niche overlap could result from resource availability, which is sufficient to satisfy all species without any strong competition; 2) or the high values of niche overlap could be a selective force driving species to compete, but there has not been enough time to express a significant divergence in the species diet because the study area is characterised as a dynamic habitat influenced by frequent and cyclical changes.
