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Evaluation of zeolite dusts as grain protectants against Lepinotus reticulatus, Liposcelis decolor, Acarus siro and Stegobium paniceum
Abstract
The insecticidal effect of two zeolite formulations was tested on wheat against adults of Lepinotus reticulatus Enderlein, Liposcelis decolor (Pearman), Acarus siro L. and Stegobium paniceum (L.). The zeolites were tested at four dose rates, i.e., 50, 100, 500 and 1000 ppm (mg per kg of wheat). The bioassays were conducted under laboratory conditions. The vials for A. siro were kept at 22°C, 60–70% relative humidity (r.h.), for psocids were kept at 30°C, 75–80% r.h., and for S. paniceum were kept at 26°C, 65–70% r.h., with continuous darkness. The bioassays were conducted in cylindrical glass vials of 20 ml (beetles and psocids) or 4 ml (mites). There were three replicates for each treatment, whereas each bioassay was repeated three times for S. paniceum and A. siro, whereas for psocids species, there were three vials for each treatment. Each vial was filled with 10 g of wheat for psocids and S. paniceum, and 2 g for A. siro. Afterward, ten adults of each species were placed in each vial, with separate series of vials per species, and all vials were kept at the aforementioned conditions. Mortality was determined after 4, 7, and 14 d of exposure for psocids, 3, 7 and 14 d of exposure for S. paniceum and 14 d of exposure for A. siro. From the species tested, L. reticulatus and S. paniceum were by far the most susceptible species, given that mortality reached 100% after 14 days of exposure. In contrast, for the other two species, mortality rate for L. decolor was 27% and for A. siro was 54% after 14 d of exposure at 1000 ppm, indicating that for these species, rapid rebound of their populations is likely to occur. The current study provides data on the toxicity of zeolites against four stored-product insect species, for which the relative data available were scarce.
... Inert materials have been proven effective both as admixture with the grains as well as surface treatment agents [5,[15][16][17][18][19][20]. Diatomaceous earths (DEs) have been extensively studied for their efficacy in the control of stored-product insects, including a plethora of published papers in this area over the last decade [21][22][23][24][25][26]. ...
... This is due to the fact that inert materials act through the cuticle, and hence, soft-bodied individuals may be more susceptible [21]. Nevertheless, this is not the case with stored-product psocids, which, although soft-bodied as well, seem to have a mechanism to moderate water loss [16,25]. ...
Different inert materials have been tested as grain protectants against stored-product mites with variable results. Most of the studies are focused on the efficacy of diatomaceous earth, but there are few comparable data on other types of inert dust. In this study, we have tested two inert materials, zeolite and kaolin, against the cheese mite Tyrophagus putrescentiae (Schrank) (Astigmata: Acaridae) on wheat. Mites were reared in the laboratory under controlled conditions of 25 °C and 80% relative humidity. Bioassays were conducted to assess the acaricidal effects of zeolite and kaolin. These formulations were applied to wheat kernels at 100, 500, and 1000 ppm. The treated wheat was manually mixed and divided into 1 g subsamples, each containing ten T. putrescentiae. Mortality was recorded after 3 and 7 days, while progeny production was assessed after 42 days. Control samples without treatment were also included, and all experiments were conducted under the same controlled conditions. Our results indicated that zeolite was more effective than kaolin, regardless of the dose rates tested. Parental mortality reached 100% on wheat treated with 1000 ppm of zeolite after only 3 days of exposure. In contrast, survival of T. putrescentiae was noted in all doses of kaolin. Moreover, progeny production in the treated substrate was not avoided even in the highest dose of kaolin but was totally (100%) suppressed at 500 and 1000 ppm. Our results illustrate that zeolite was very effective for the control of this species, even at short exposure intervals, and hence, can be considered further as a grain protectant.
... Inert dusts are promising alternatives to conventional insecticides against numerous stored-product pests [11,[15][16][17][18][19][20][21][22]. According to their chemical and physical composition, they are divided into several categories, such as (a) zeolite [22][23][24]; (b) attapulgite [20]; (c) graphene [21]; (d) wood ash [17]; and (e) diatomaceous earth (DE) [25][26][27][28][29][30][31]. ...
... Inert dusts are promising alternatives to conventional insecticides against numerous stored-product pests [11,[15][16][17][18][19][20][21][22]. According to their chemical and physical composition, they are divided into several categories, such as (a) zeolite [22][23][24]; (b) attapulgite [20]; (c) graphene [21]; (d) wood ash [17]; and (e) diatomaceous earth (DE) [25][26][27][28][29][30][31]. One of the well-studied categories is diatomaceous earth, which is registered for direct application on grains in many parts of the world [30]. ...
... Inert dusts are promising alternatives to conventional insecticides against numerous stored-product pests [11,[15][16][17][18][19][20][21][22]. According to their chemical and physical composition, they are divided into several categories, such as (a) zeolite [22][23][24]; (b) attapulgite [20]; (c) graphene [21]; (d) wood ash [17]; and (e) diatomaceous earth (DE) [25][26][27][28][29][30][31]. ...
... Inert dusts are promising alternatives to conventional insecticides against numerous stored-product pests [11,[15][16][17][18][19][20][21][22]. According to their chemical and physical composition, they are divided into several categories, such as (a) zeolite [22][23][24]; (b) attapulgite [20]; (c) graphene [21]; (d) wood ash [17]; and (e) diatomaceous earth (DE) [25][26][27][28][29][30][31]. One of the well-studied categories is diatomaceous earth, which is registered for direct application on grains in many parts of the world [30]. ...
Simple Summary
Inert dusts are promising alternatives to conventional insecticides against numerous stored-product insect species. Diatomaceous earth formulations are based on natural substances and are registered for direct application on grain in many parts of the world. The objective of this study was to evaluate the effectiveness of three diatomaceous earth formulations (namely Silicid, Celatom® MN-23, and SilicoSec®) against adults of a wide range of stored-product beetle species. Specifically, seven stored-grain beetle species were tested, including three primary colonizers and four secondary colonizers, which are commonly found in stored cereals and other relevant commodities in Greece. The experimental units for the bioassays were plastic cylindrical vials. Twenty grams of soft wheat was filled in each vial and twenty adults of each species were placed in each vial, with a separate series of vials for each species. Mortality levels were recorded after 3, 7, 14, and 21 days of exposure. After that, the vials were kept for additional 65 days to assess progeny production. Our results indicate that among the tested diatomaceous earth formulations, the application of Silicid resulted in complete control of the major stored-product insect species. Offspring production was noted only for primary colonizers.
Abstract
Diatomaceous earth (DE) formulations are promising alternatives over the use of traditional insecticides. In the present study, a series of laboratory bioassays was carried out to assess the efficacy of three diatomaceous earth formulations, i.e., Silicid, Celatom® MN-23, and SilicoSec®, for the control of a wide range of stored-product insect species in soft wheat. The species tested were Tribolium confusum, Tribolium castaneum, Sitophilus oryzae, Sitophilus granarius, Rhyzopertha dominica, Oryzaephilus surinamensis, and Alphitobious diaperinus. Different dose rates, i.e., 0 (control), 100, 300, 500, and 1000 ppm, were used for each of the aforementioned dust formulations. Mortality levels of the exposed individuals were assessed after 3, 7, 14, and 21 days of exposure. Moreover, progeny were counted 65 days later. Based on our results, dust formulations were effective for the control of most of the stored-product beetle species tested. Among the DE formulations tested, Silicid could adequately control the stored-product insect species. Complete suppression of offspring was observed only for secondary species (T. confusum, T. castaneum, O. surinamensis, and A. diaperinus). For primary species (S. oryzae, S. granarius, and R. dominica), the lowest number of progeny was observed in wheat treated with Silicid. For instance, in the case of R. dominica, significantly fewer individuals were produced in Silicid-treated wheat at the highest dose rate. The results of the present study aim to encourage the utilization of DE in stored-product protection as an integrated pest management tool. Additional experimentation is required to apply the tested DE formulations in the field and on different surfaces.
... Several scientific studies have documented the degradation of plastic polymers by various insect species. For instance, the degradation of polyether-polyurethane foam by Tenebrio molitor , polystyrene by Zophobas atratus (Kim et al. 2020), low-density polyethylene and polystyrene by Galleria mellonella (Lou et al., 2020), polyethylene by Plodia interpunctella , polystyrene by Tribolium castaneum , polystyrene and polyethylene by Tribolium confusum (Bilal et al., 2021), high-density polyethylene by Achroia grisella (Kundungal et al., 2019), polyvinyl chloride by Spodoptera frugiperda (Zhang et al., 2022), low-density polyethylene by Corcyra cephalonica (Kesti and Thimmappa, 2019), and polystyrene by Stegobium paniceum (Agrafioti et al., 2023). Peng et al. (2019) revealed that Tenebrio obscurus had a greater capacity for polystyrene breakdown throughout the gastrointestinal tract (26.03%) compared to Tenebrio molitor (11.67%). ...
... The death of insects increased with the increase in zeolite dosage and contact time (Ibrahim and Salem, 2019). Zeolites were proven effective against other pantry insects as well such as reticulate-winged trogiid (Lepinotus reticulatus), Liposcelis decolor, Acarus siro and Stegobium paniceum (Agrafioti et al., 2023). These studies confirmed the role of zeolites in protecting crops from various kinds of pathogens, eventually enhancing crop quality and quantity, leading towards cleaner agricultural production. ...
Plants are exposed to different types of biotic and abiotic stresses that reduce growth and yield. The review presents the negative effects posed by salinity, water scarcity and phytotoxic metals to the agriculture sector and underscores the protective role of natural and synthetic zeolites to improve the unfavourable growth environment. Furthermore, based on extensive literature review, zeolites (specifically natural zeolites) possess extraordinary adsorption capacity, highly functional nutrient and water holding and releasing characteristics. The enhanced and selective nutrient retention capacity of zeolites enables lower nutrient loss from soil, thereby minimizing the issue of water pollution through the leaching of excessive nutrients. The adsorption potential of zeolites against Na+, Cl- and various phytotoxic metals in soils improve the growth environment for the plants. Sepcifically, the addition of zeolites to soil facilitates improvements in water availability and better plant growth parameters: chlorophyll content, total protein concentration, and increased activity of antioxidant defense; eventually mitigating the unfavourable effects of environmental stresses such as extreme temperatures, drought or salinity. Natural zeolites, particularly clinoptilolite, were shown to be better in alleviating plant stresses such as salinity in comparison to synthetic zeolites; handling salt load of up to 100 mM of NaCl. Interestingly, zeolites can be used in combination with other substances such as compost, biochar or calcium-based materials to reduce salinity. The greater availability of hydrophilic active sites in zeolites enhances their water sorption strength, restricting the formation of liquid film required for growth of pathogens; delivering effective desiccant-like effects to protect the plants from several pathogens. In general, zeolite applications can be used as buffering agents to improve plant growth and to deliver better biological resilience during different unfavourable growth conditions.
Nowadays, we are tackling various issues related to the overuse of synthetic insecticides. Growing concerns about biodiversity, animal and human welfare, and food security are pushing agriculture toward a more sustainable approach, and research is moving in this direction, looking for environmentally friendly alternatives to be adopted in Integrated Pest Management (IPM) protocols. In this regard, inert dusts, especially diatomaceous earths (DEs), hold a significant promise to prevent and control a wide range of arthropod pests. DEs are a type of naturally occurring soft siliceous sedimentary rock, consisting of the fossilized exoskeleton of unicellular algae, which are called diatoms. Mainly adopted for the control of stored product pests, DEs have found also their use against some household insects living in a dry environment, such as bed bugs, or insects of agricultural interest. In this article, we reported a comprehensive review of the use of DEs against different arthropod pest taxa, such as Acarina, Blattodea, Coleoptera, Diptera, Hemiptera, Hymenoptera, Ixodida, Lepidoptera, when applied either alone or in combination with other techniques. The mechanisms of action of DEs, their real-world applications, and challenges related to their adoption in IPM programs are critically reported.
The insecticidal potential of two natural zeolite formulations, Zeocem and Mycostop, was tested against the rice weevil Sitophilus oryzae (L.) and the sawtoothed grain beetle Oryzaephilus surinamensis (L.) on wheat, at the dose rates of 0.25, 0.50, 0.75, and 1 g/kg. The bioassays were carried out under laboratory conditions at three temperature levels (20, 25, and 30οC) and two relative humidity (r.h.) levels (55, 75%). Mortality was recorded after 7, 14, and 21 d of exposure and progeny production was recorded 65 d later. Complete (100%) mortality was achieved only for O. surinamensis adults with Zeocem for most temperature and r.h. combinations tested. Progeny production for this species was extremely low. In contrast, mortality for S. oryzae was much lower and did not exceed 87% after 21 days at any of the combinations tested, while progeny production was high. For O. surinamensis exposed to Mycostop, mortality after 21 days did not exceed 97% for all temperature and r.h combinations, while overall progeny production was low. Moreover, S. oryzae mortality was generally low and did not exceed 56%, while progeny production for this species was high for most temperature and r.h. combinations. Despite the fact that some general trends were evident, the effect of temperarature and r.h. in zeolite efficacy was often found inconclusive. The results of the present study illustrated the insecticidal potential of zeolites for the contol of certain stored product insect species, which requires additional investigation.
The insect growth regulator methoprene was evaluated for control of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), Liposcelis entomophila (Enderlein), Liposcelis paeta Pearman (Psocoptera: Liposcelididae), and Lepinotus reticulatus Enderlein (Trogiidae) at application rates of 1, 5, and 10 ppm on maize, wheat, and rice. Methoprene did not completely suppress progeny production during the 40-day test period, but did cause a significant reduction in adult progeny in all psocid species at the application rates of 5 and 10 ppm. At 1 ppm, numbers of adults were reduced for all species on wheat and maize, but only for L. paeta on rice. Nevertheless, the numbers of nymphs present after 40 days generally were not reduced, relative to the controls. Methoprene applied at rates of 1 to 10 ppm to stored grain would not provide adequate control of psocids.
Despite numerous advantages of diatomaceous earth (DE), its use for direct
mixing with grains to control stored-product insects remains limited because
of some very serious obstacles and disadvantages. The main obstacles
preventing a wider use of DEs for mixing with grain, such as health concerns,
the reduction in bulk density, differences in insect species tolerance to the
same DE formulation, the effects of grain moisture and temperature on the
effectiveness against insects, the influence of various commodities on DE
efficacy, the use of DEs in some other fields, and possible solutions for
overcoming DE limitations during direct mixing with grains are described in
this manuscript. The same attempts have been made to discover new ways of
increasing significantly the effectiveness against insects when much lower
concentrations are used for direct mixing with grains. If these newer
enhanced formulations can respond to the existing limitations of diatomaceous
earth, a wider utilization of diatomaceous earth may be expected to control
stored-product insect pests.
We evaluated the competition among stored-product psocid species by conducting two series of laboratory experiments. In the first series, three species of Liposcelididae were used: Liposcelis bostrychophila, Liposcelis decolor, and Liposcelis paeta. Five adult females of these species were placed in vials containing wheat, either alone or in all possible combinations of two species. The number of adults in the vials was counted after 35, 70, 105, 140, and 175 days. These tests were performed at 25 and 30°C. At 25°C, there were no differences in numbers of L. bostrychophila when this species was reared either alone or with each of the other two species. At 30°C, L. bostrychophila was the dominant species. The presence of L. bostrychophila had a negative effect on the growth of populations of L. decolor and L. paeta. The presence of L. paeta did not affect growth of populations of L. decolor, although the presence of L. decolor occasionally reduced growth of populations of L. paeta. In the second series of tests, L. bostrychophila adult females were placed in vials of wheat either alone or with adult females of Lepinotus reticulatus, at the ratios of (L. bostrychophila: L. reticulatus) 10∶0, 9∶1, 7∶3, 5∶5, 3∶7, 1∶9, and 0∶10. These tests were carried out only at 30°C, and the observation periods were the same as for the first series of tests. Liposcelis bostrychophila was the dominant species in this case as well, regardless of the ratio of the parental females. At the end of the experimental period, L. reticulatus was present only in vials that contained this species alone. Our results showed that L. bostrychophila outcompetes the other stored-product psocid species tested.
The insecticidal efficacy of the diatomaceous earth (DE) formulation SilicoSec (Biofa GmbH) against adults and larvae of the confused flour beetle, Tribolium confusum DuVal (Coleoptera: Tenebrionidae) was evaluated in laboratory tests. These tests were conducted at five temperatures, 22°C, 25°C, 27°C, 30°C and 32°C, and two relative humidity levels, 55% and 65%. SilicoSec was applied to three types of product, hard wheat, soft wheat and wheat flour, at four dose rates, 0.25, 0.5, 1 and 1.5g/kg of each product. In order to assess the influence of larval instar on the efficacy of SilicoSec, the larvae were divided into two groups, young and old larvae, corresponding to 1–3 and 4–7 instar larvae, respectively. Similarly, adults were divided into three different groups, 1, 2 and 7-d old adults, respectively. For both adults and larvae, mortality on wheat or flour treated with SilicoSec increased with the exposure interval and the dose rate. Larvae were more sensitive to DE than adults, given that adults could survive exposure intervals and application rates that were lethal to larvae. The mortality of larvae and adults exposed to SilicoSec increased with increasing temperature. In contrast, the efficacy of SilicoSec notably decreased with the increase of relative humidity from 55% to 65%. Significantly, more adults and larvae were dead in SilicoSec-treated wheat than in treated flour. The efficacy of SilicoSec was substantially affected by the age of the exposed individuals. Young larvae were significantly more sensitive than old ones. Adults became significantly less susceptible to SilicoSec as their age increased from 1 to 2 and to 7d.
The efficacy of diatomaceous earth (DE) against insects depends greatly on several physical properties of the diatom particles. Ideally, active DE should have an high amorphous silicon dioxide content with a uniform particle size (less than 10 μm), a high oil sorption capacity, a large active surface, and very little clay and other impurities. The analysis of physical and chemical properties of DE is time-consuming and expensive, and can be conducted only by experts at specially equipped laboratories. Therefore, in the past, bioassay was considered the most important criterion for the assessment of the efficacy of DE against insects. These methods are relatively expensive and time-consuming also, since they require an expert and a well-equipped entomological laboratory. After conducting numerous experiments with 36 different diatomaceous earths or formulations collected from the U.S.A., Mexico, Canada, Australia, Japan, China, and Macedonia (Europe), results indicate that the efficacy of DE against insects depends on different properties of the diatom particles. Properties include the ability of DE particles to reduce bulk grain density (test weight), DE tapped and loose density, the tendency of DE particles to adhere on the grain surface, particle size distribution, diatom shape, and pH. It is possible to evaluate and to predict the insecticidal value of diatomaceous earth mainly by very simple and low-cost analysis of these properties of DE without bioassays or extensive physical and chemical analyses.
The use of diatomaceous earths (DEs) provides a promising alternative to the use of contact insecticides in stored-product IPM. Geographical origin and the physical properties of a given DE may affect its insecticidal activity. In the present study, DE samples were collected from different locations of south-eastern Europe, and their efficacy was evaluated in the laboratory against Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujiidae), Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae). In addition, three fractions comprising particles of different size were obtained from each DE sample and assessed with regards to their effectiveness against the above stored-product insect pests.
DE from the Greek region of Elassona was the most effective against C. ferrugineus and S. oryzae, whereas the DE Kolubara 518, mined in the Serbian region of Kolubara, was the most effective against R. dominica. Smaller particles were more effective than larger particles against the three tested species, although significant differences in the efficacy of fractions containing particles of 0-150 microm and particles with sizes of < 45 microm were not always recorded.
Deposits from south-eastern Europe appeared to be very effective against the tested species, and therefore this region should be further evaluated as a source of development of commercial products. Particle size is a physical property that should always be taken into account during the DE manufacturing process, as it can strongly influence the insecticidal action of a given product.
These proceedings contain nearly 200 keynote, oral and poster papers and contributions highlighting the work on the pests and diseases that cause spoilage, adverse health effects and crop losses after harvest, and discussing new techniques for safe, effective and environmentally friendly management of stored commodities. The contents cover the future of stored product protection and the impacts of global issues, food safety, chemical and physical control, and processing and applications.
The cigarette beetle, Lasioderma serricorne(F.) (Coleoptera: Anobiidae), is an important pest in the food and tobacco industry in many regions of the world. Despite a great deal of research, control of this pest still relies on the use of phosphine fumigation, which is becoming less effective as the insect develops resistance to this compound. In addition, series of other nonchemical methods used to control the insect have given mixed and irregular results. This review summarizes and discusses information on important aspects of the biology and ecology of the cigarette beetle, and its control. The topics covered include a taxonomic discussion of the cigarette beetle, which includes a discussion of other anobiid species of economic importance. The mating behavior of the insect and conditions favorable for pest development were described. The review also includes a discussion of the life stages of the insect, its feeding habit, and economic damage. Important aspects of its chemical ecology and a discussion on the association between this species and its microorganisms, and major natural enemies, were presented. A summary of its flight behavior, including the factors governing flight initiation and temporal and seasonal flight activity were reviewed. Finally, the control methods currently used in the management of the insect were described. The review also identifies potential areas of further research on L. serricorne and gives an analysis of the control methods worthy of further investigation in the search for practical and sustainable methods for the management of this pest.
The mould mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) and the flour mite, Acarus siro L. (Sarcoptiformes: Acaridae) are very common stored-product mites found in a wide spectrum of commodities of both plant and animal origin. In this study, we evaluated three zeolite formulations as stored-wheat protectants regarding the management of larvae, nymphs and adults of T. putrescentiae and A. siro at different exposure intervals, i.e., 1, 2, and 5 days (d), and doses, i.e., 200, 500, and 1000 ppm. We found that the zeolite formulations tested here can be effective for the control of both stored-product mite species. Mortality of all stages of T. putrescentiae and A. siro was considerably affected by dose and exposure intervals, i.e. the higher the dose and the longer the exposure time, the greater the mortality. Nevertheless, 100% mortality was not recorded on any of the life stages and formulations tested, even in the case of the highest dose and the longest exposure interval. All zeolite formulations provided the same efficacy level, which was similar for immature stages and adults of both mite species. The results of the present study suggest that longer exposures of the evaluated zeolite formulations are required to increase the efficacy on the control of T. putrescentiae and A. siro.
Insects and mites are common inhabitants and accidental invaders of food, including durable commodities, and their presence can have both direct and indirect effects on human health. The most common direct effect is contamination of food with arthropod fragments and related contaminants, which may be allergenic or even carcinogenic. The most important indirect effect is that their presence can change the storage microenvironment, making durable products suitable for the rapid development of fungi and other microorganisms. Some of these fungi can produce toxins (e.g., aflatoxins) that endanger human health. Insects may actively or passively contribute to the spread of microorganisms, increasing product contamination, and they may host bacteria that have developed antibiotic resistance, contributing to their spread in food. Several species also may host, attract, or transmit tapeworms, predators, or parasitoids that may affect health. This review synthesizes research on these topics and suggests directions for future research
Zeolites are crystalline hydrated aluminosilicates with remarkable physical and chemical properties including losing and receiving water in a reverse way, adsorbing molecules that act as molecular sieves, and replacing their constituent cations without structural change. Commercial production of natural zeolites has accelerated during last fifty years. The Structure Commission of the International Zeolite Association recorded more than 200 zeolites which currently include more than 40 naturally occurring zeolites. Recent findings supported their role in stored-pest management as inert dust applications, pesticide and fertilizer carriers, soil amendments, animal feed additives, mycotoxin binders and food packaging materials. There are many advantages of inert dust application including low cost, non-neurotoxic action, low mammalian toxicity and safety for human consumption. Latest consumer trends and government protocols have shifted toward organic origin materials to replace synthetic chemical products. In the current review, we summarized most of the main uses of zeolites in food and agruculture, with specific paradigms that illustrate their important role.
Previously regarded as minor nuisance pests, psocids belonging to the genus Liposcelis now pose a major problem for the effective protection of stored products worldwide. Here we examine the apparent biological and operational reasons behind this phenomenon and why conventional pest management seems to be failing. We investigate what is known about the biology, behavior, and population dynamics of major pest species to ascertain their strengths, and perhaps find weaknesses, as a basis for a rational pest management strategy. We outline the contribution of molecular techniques to clarifying species identification and understanding genetic diversity. We discuss progress in sampling and trapping and our comprehension of spatial distribution of these pests as a foundation for developing management strategies. The effectiveness of various chemical treatments and the availability and potential of nonchemical control methods are critically examined. Finally, we identify research gaps and suggest future directions for research. Expected final online publication date for the Annual Review of Entomology Volume 59 is January 07, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
The lethality impact of diatomaceous earth (Sayan®), bran, sawdust and clay on six major stored-product insects under laboratory conditions was determined. The lethal effects were investigated in two different methods. In the first method, experimental surface was permeated with test material, and in the second method, the test compounds were mixed with rearing mediums separately. In the first technique, adults of Sitophilus oryzae, Rhyzopertha dominica, Oryzephilus surinamensis, Lasioderma serricorne, Cryptolestes ferrugineus and Callosobruchus maculatus were placed in a Petri dish, which was contaminated with a known amount of Sayan®, bran, sawdust or clay. Mortality rate was recorded at 24, 48 and 72 h after commence of each exposure. In the second method, the lethality of test compounds which were mixed with wheat was investigated against S. oryzae, R. dominica, O. surinamensis, L. serricorne and C. ferrugineus for 1, 7 and 14 days of exposure. In the first technique, the results indicated that bran and sawdust caused more mortality rate on S. oryzae compared to Sayan®. In the second method, the results demonstrated a higher mortality caused by bran and sawdust compared to Sayan® on S. oryzae. For L. serricorne, mortality rate caused by bran and sawdust was similar, whereas, in C. maculates case, mortality rate caused by bran was more than the other treatments. The protective effects of test compounds on life span of S. oryzae and R. dominica showed significant differences among the emerged adult of insects in different treatments. In the bran treatment, S. oryzae adult's emergence was the lowest, while, in the R. dominica case, a non-significant difference among resultant number of adult insects was detected.
Water vapour absorption is shown to occur in 22 species of Psocoptera inhabiting diverse environments and representing all major groups of this insect order. Evidently the faculty is a common feature of the whole order and it seems not to be related to specific environmental conditions. For the first time water vapour uptake could be demonstrated in fully winged and flying insects. The critical equilibrium humidities vary considerably among different species ranging from 58 to 85% r.h. Marked interspecific differences are also observed in water loss and uptake rates but no clear correlation with habitat or systematic group is recognizable. The uptake rates of Psocoptera are among the highest of all arthropods investigated so far. From weight recordings with a sensitive microbalance it could be seen that continuous operation of the uptake mechanism is restricted to limited periods of time of less than 1 hr regardless of the water status of the animals. Initiation and termination of the uptake process are abrupt and continuous uptake proceeds at a constant rate at a given relative humidity. Uptake rates are humidity-dependent decreasing with falling relative humidity whereas the adjustment of the equilibrium level of body water is independent of ambient humidity. Equilibrium is maintained by intermittent operation of the uptake mechanism within ca. 3% of body water mass. The uptake mechanism exhibits marked sensitivity to starvation in most members of the Psocomorpha. Some features of the uptake process of Psocoptera are in close agreement with those of Mallophaga reflecting the close relationship between the two groups.
Twenty-five kilograms of wheat, at 16 and 17% moisture content (MC) were treated with ‘Dryacide’, a diatomaceous earth, at 3 and 5 g kg−1 and stored in metal bins. The bins were then infested with mixed populations of mites (Acarus siro and Lepidoglyphus destructor) and insects (Sitophilus granarius and Oryzaephilus surinamensis) at approximately 100 and 10 per kg, respectively. The grain was held at a constant temperature of 15 °C and relative humidities of 75 and 80%, chosen to simulate bulk surface conditions in UK stores, and monitored for 42 weeks. At 16% MC, the mite and insect populations were suppressed within 2 and 13 weeks, respectively, at both doses. At 17% MC, the mites took 5 weeks to die out and F1 adults of S granarius emerging within 22 weeks were controlled after a further 5 weeks. After 23 weeks the bins were re-infested with mites and these were completely suppressed after a further 3 weeks. There was no decline in efficacy throughout the experiment.© Crown Copyright 2000. Reproduced with the permission of Her Majesty's Stationery Office. Published for SCI by John Wiley & Sons, Ltd.
In the Psocoptera, occlusion of the anus or extended areas of the thorax and abdomen with paraffin wax does not interfere with the active uptake of water vapour from subsaturated atmospheres. However, blocking the mouth or impairing the mobility of the mouthparts with wax prevents watervapour absorption. Observations of the animals synchronized with continuous weight recordings, confirm an oral site of water-vapour uptake in this insect order, and reveal some details of the uptake mechanism. During uptake, paired lingual sclerites of the ventral hypopharyngeal surface are brought into a typical absorbing position. Water-vapour condensation proceeds onto a fluid layer covering this surface. The fluid presumably originates from a pair of dorsal labial glands. The condensed water vapour is transferred from the site of condensation to the gut entrance via a paired or branched sclerotized tubule traversing the hypopharynx. Propulsion of the fluid is achieved by a cibarial sucking pump. Below the critical equilibrium humidity the fluid layer dries up, the salivarium is closed and absorption ceases.
Exposure studies were carried out in the laboratory to assess the insecticidal effect of the formulation PyriSec®, which contains diatomaceous earth with natural pyrethrum and piperonyl butoxide, against Rhyzopertha dominica (F.). PyriSec® was applied to eight grain commodities: wheat, whole barley, peeled barley, oats, rye, triticale, rice and maize, at three doses 0.75, 1 and 1.5 g/kg of grain. Dead R. dominica adults were counted after exposure to treated grain for 24 h, 48 h, 7 d and 14 d at 26 °C and 55% r.h. After the termination of the 14-d-interval count, the treated quantities remained in the same conditions for an additional 60-d incubation period, and the progeny production was recorded. Mortality of R. dominica adults notably varied according to the commodity, but, in most cases more than 50% of the exposed adults were dead after only 24 h of exposure. After 14 d of exposure, adult mortality was ⩾95% in all grains treated with the highest PyriSec® dose, with the exception of peeled barley, where the respective figure was 84.2%. No progeny was found in the grains treated with the highest PyriSec® rate, but the number of F1 individuals was low even in the case of the lowest PyriSec® rate. Significant differences in the degree of PyriSec® retention in kernels were noted among the eight grains tested. The highest retention level was noted for rice (91.4%) and the lowest for maize (10.1%). However, the degree of retention to a given grain was not indicative of the effectiveness of PyriSec® against R. dominica.
A thorough review of the literature has identified the key factors and interactions that affect the growth of mite pests on stored grain commodities. Although many factors influence mite growth, the change and combinations of the physical conditions (temperature, relative humidity and/or moisture content) during the storage period are likely to have the greatest impact, with biological factors (e.g. predators and commodity) playing an important role. There is limited information on the effects of climate change, light, species interactions, local density dependant factors, spread of mycotoxins and action thresholds for mites. A greater understanding of these factors may identify alternative control techniques. The ability to predict mite population dynamics over a range of environmental conditions, both physical and biological, is essential in providing an early warning of mite infestations, advising when appropriate control measures are required and for evaluating control measures. This information may provide a useful aid in predicting and preventing mite population development as part of a risk based decision support system.
We evaluated the efficacy of three diatomaceous earth (DE) formulations, Dryacide, Protect-It, and Insecto, against three Psocoptera species, Liposcelis entomophila (Enderlein) (Liposcelididae), Lepinotus reticulatus Enderlein (Trogiidae), and Liposcelis decolor (Pearman), in the laboratory. Bioassays were conducted in three grain commodities, wheat, rice and maize, at 30 degrees C and 75% RH, and the DEs were applied at the recommended dose rates of 1,000, 400, and 500 ppm for Dryacide, Protect-It, and Insecto, respectively. Differences in adult mortality were found among grains and DEs for L. entomophila and L. reticulatus, but these trends were not consistent for all combinations tested. Type of grain and DE did not affect L. decolor mortality significantly. Moreover, mortality increased with increasing exposure time for L. entomophila and L. reticulatus, but there was no effect of exposure time on L. decolor. After 7 d of exposure, mortalities of L. entomophila, L. reticulatus, and L. decolor were 56, 55, and 40%, respectively, and the respective mortality levels after 14 d were 63, 71, and 42%. Progeny production after 30 d was significantly suppressed for all species in the treated grains. However, progeny production was still high in the treated grains and reached 54, 42, and 76 individuals/10 g of grain for L. entomophila, L. reticulatus, and L. decolor, respectively. Progeny production did not vary with commodity. Our results suggest that DEs, when used alone, will not provide effective control of psocids.
Psocids are emerging pests in stored products, particularly in amylaceous commodities such as grains. Currently, their control is based on the use of fumigants and contact insecticides; however, newer data indicate that psocids are tolerant to insecticides used to control other stored-grain species. This study evaluated the insecticides registered in the USA for use on stored maize, rice and wheat for control of the psocid species Lepinotus reticulatus, Liposcelis entomophila, L. bostrychophila and L. paeta. Mortality of exposed adult females was recorded after 7 and 14 days of exposure, while progeny production was assessed after 30 days of exposure.
On wheat and rice, chlorpyriphos-methyl + deltamethrin was generally more effective against exposed parental adults than spinosad or pyrethrin, while pirimiphos-methyl was more effective on maize than spinosad or pyrethrin. In most cases, progeny production was suppressed in the treated grains. Progeny production was consistently lowest on wheat and rice treated with chlorpyriphos-methyl + deltamethrin and maize treated with pirimiphos-methyl.
Chlorpyriphos-methyl + deltamethrin and pirimiphos-methyl were the most effective insecticides for all species and commodities. Conversely, efficacy of spinosad or pyrethrum was highly dependent on the psocid species and commodity.
The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C21-C34), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C28-C42, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-) with a carbon number range of C31-C41 were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C16-C22 in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C16:1, C16:0, C18:2, C18:1, and C18:0 in chain length) and three straight chain aldehydes (C15, C16, and C17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.
Laboratory bioassays were carried out in order to evaluate the effectiveness of two diatomaceous earth (DE) formulations, Insecto and SilicoSec, against adults of Rhyzopertha dominica (F) in eight different grain commodities. The adherence of the two DEs to each grain was also measured. The eight grains tested were wheat, whole barley, peeled barley, oats, rye, triticale, rice and maize. These commodities were treated with the DEs at three rates, 0.75, 1.0 and 1.5 g DE kg(-1) grain. The mortality of R dominica adults was measured after 24 h, 48 h, 7 days and 14 days of exposure in the treated grains at 26 degrees C and 55% RH. After the 14-day mortality count, all adults were removed and the treated grains retained under the same conditions for a further 60 days. The treated grains were subsequently examined for F1 progeny. Significant differences were recorded among the eight grain types as well as between the DE formulations tested. After 14 days of exposure, even at the lowest DE rate for both formulations, adult mortality was high (>90%) in wheat and triticale. In contrast, adult mortality was significantly lower in peeled barley. Increasing the rate improved the efficacy of the DEs significantly in only some of the grains tested. Reproductive capacity in all the treated grains was significantly suppressed when compared with untreated grains. Generally, more F1 individuals of R dominica were noted in the treated peeled barley than in the other commodities. Significant differences in the percentage of DE retention were noted among the eight grains. The highest retention level was noted in rice (>87%) and the lowest in maize (<6%). However, the degree of DE adherence to a given grain was not always indicative of the effectiveness of DE against R dominica.
Acaricidal effect of a diatomaceous earth formulation against Tyrophagus putrescentiae (Astigmata: acaridae) and its predator cheyletus malaccensis (prostigmata: cheyletidae) in four grain commodities
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Diatomaceous earths as alternatives to organophosporous (OP) pesticide treatments on stored grain in the UK
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Acaricidal effect of a diatomaceous earth formulation against Tyrophagus putrescentiae (Astigmata: acaridae) and its predator cheyletus malaccensis
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The effect of relative humidity on the efficacy of the diatomaceous earth Protect-It against L. entomophila (Enderlein) (Psocoptera: liposcelidae)
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