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Effectiveness of four native entomopathogenic nematodes isolates on Bactrocera oleae (DIPTERA: Tephritidae) pupae at different temperatures
Abstract
Türkiye, is the country of origin of olive trees and being among the world’s leading olive producers. Apparently, most of the olive production is concentrated in Türkiye include Izmir, Aydın, Çanakkale, Balıkesir, Muğla and Bursa provinces. Bactrocera oleae (DIPTERA: Tephritidae), being one of the main pests of olive trees, is an important problem in olive cultivation in Türkiye. Four local entomopathogenic nematode species (S. feltiae/12, S. carpocapsae/1133, H. bacteriophora/70, H. bacteriophora/91), which were detected in different regions of Türkiye by our previous studies, were tested by using a single dose and at 5 different temperatures (10, 15, 20, 25 ve 30 °C). Efficacy of four entomopathogenic nematodes infection rates on B. oleae pupae was determined under laboratory conditions. According to the obtained results, the highest infection rate was observed by Heterorhabditis bacteriophora/91 isolate at 25 °C, and the lowest infection rate was observed by Steinernema feltiae/12 isolate at 10 °C.
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Ephestia cautella (Walker) (Lepidoptera: Phycitidae) is one of the main pests that cause damage to stored products in many parts of the world. In this study, the effectiveness of the entomopathogenic nematode Steinernema carpocapsae (Rhabditida: Steinernematidae) (Tokat-Bakışlı05) on the Ephestia cautella under laboratory conditions was investigated. Experiments were carried out with 2 replications and 5 replications at 3 different temperatures (10, 20, 25°C) and 65% humidity conditions. S. carpocapsae isolate was applied at three different concentrations (250, 500 and 1000 IJs ml-1), and pure water was used as a control. As a result of the experiment, Steinernema carpocapsae (Tokat-Bakışlı 05) isolate was found to be 100% effective in 1000 IJs ml-1 at 20 0C.
Entomopathogenic nematodes (EPN) have an important potential in the biological control of agricultural soil pests. Efficacy and persistence of native EPN species from Turkey were investigated against Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) larvae with different irrigation methods in a peach (Prunus persica L. Rosaceae) orchard for two years. Four native EPN species, Steinernema carpocapsae Weiser (Nematoda: Steinernematidae), S. feltiae Filipjev (Nematoda: Steinernematidae), S. affine Bovien (Nematoda: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae), were applied to soil via drip irrigation, surface irrigation and soil injection methods to determine the mortalities of C. tenebrionis neonate larvae caused by these species naturally. In all applications, EPNs were applied as 50 IJs/cm². Mortalities were calculated on the 1st, 3rd, 5th and 7th days of the experiment. The results of the study indicated that on the first day of surface irrigation, the highest mortality was found in H. bacteriophora with 87.5% and the lowest mortality was found in S. feltiae with 16.6% in 2018. In 2019, however, the highest mortality on the first day was from S. affine with 91% and the lowest was from both S. carpocapsae and S. feltiae with 33.3%. EPN persistence in soil was found to be 90 days in 2018, while it was 150 days in 2019. In all EPN treatments, 100% mortality was reached on the fifth day indicating all EPN treatments were highly effective. Based on the study results, it can be concluded that farmers might be able to control C. tenebrionis damage by using EPN in their regular irrigation calendar.
In this study the virulence of Steinernema affine 46, S. feltiae 96, S. carpocapsae 1133 and Heterorhabditis bacteriophora 1144 isolates against the last instar larvae of Palpita unionalis (Hübner) were investigated on plates in laboratory and pots in a climate room. Efficacy of entomopathogenic nematodes were determined at 25 oC using two different application doses (25 and 50 Infective Juveniles (IJs)/larva) in 12 well plates. In pot experiment, 10 P. unionalis larvae were inoculated in each pot, by using a single application dose (40.000 IJs/pot) at 25 oC. Depending on the nematode species and application dose, the larvae mortality occurred in plates was 83.3-100%, while the mortality in pots was 50-100%. Among the EPN species used in both plate and pot experiments, H. bacteriophora resulted in the highest efficacy on P. unionalis larvae with 90-100% mortality.
Wheat is one of the most important cultivated plants in our country. The main pest that causes economic losses in wheat production is sunn pest Eurygaster integriceps. In this study the mortality of three native entomopathogenic nematodes (EPNs) species Steinernema feltiae (Yalova), S. carpocapsae (Sakarya) and Heterorhabditis bacteriophora (Sakarya) by two application doses (500-1000 IJs/adult) on the sunn pest adults were determined at 25 oC under laboratory conditions. According to the results, the highest mortality on the sunn pest adults was determined at the end of the 7th day of applications with 1000 IJs dose as 100, 92 and 100% for S. feltiae, H. bacteriophora and S. carpocapsae species, respectively. These results showed that the infecting rate of native EPN species used in the study can reach high levels against the adults of sunn pest.
Two Turkish entomopathogenic nematodes isolates, Steinernema feltiae-KV06 (Filipjev) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora-EO7 (Rhabditida: Heterorhabtidae), were tested against the cockroach, Blatta lateralis Walker (Blattodea: Blattidae) to determine their potential for its control. The isolates were obtained from Kelebekler Vadisi and Eğriova Nature Parks in Ankara Province, Turkey. These isolates were applied at concentrations of 100, 250, 500 and 1000 IJ/cm2 to B. lateralis nymphs in 9cm diameter Petri dishes. The mortalities were recorded at 2, 4, 6, 8, 10, 12 and 14 days after application. At 1000 IJs/cm2, S. feltiae-KV06 and H. bacteriophora-EO7 caused the highest mortality (100.0±0.0%) with an LT50 of 2.3 and 2.6 days, respectively, and an LT90 of 6.6 and 7.9 days, respectively. The lowest mortality rate caused by both species was at 100IJs/cm2 after 2 days of exposure (S. feltiae-KV06: 0.6±1.4; H. bacteriophora-EO7: 0.0±0.0). There was no significant difference in the efficacy of the isolates at all concentrations and for all time periods. The effectiveness of both isolates against this pest should be tested at different temperatures and humidities and on different surfaces such as ceramic, concrete and parquet.
The olive fruit fly Bactrocera oleae is one of the most serious and economically damaging insects worldwide, affecting the quality and quantity of both olive oil and table olives. Laboratory bioassays were conducted for the first time to evaluate the susceptibility of B. oleae pupae to two entomopathogenic nematodes (EPN) species, Steinernema carpocapsae and Heterorhabditis bacteriophora. The nematodes tested caused pupal mortality of 62.5% and 40.6%, respectively. The most noteworthy result was obtained with S. carpocapsae which was able to infect 21.9% of the emerged adults. Since this tephritid fly spent several months in the soil as pupa, the use of EPNs could be a promising method to control this pest.
Background:
Caribbean fruit fly (Caribfly) is a serious economic insect pest because of development of larvae that hatch from eggs oviposited into fruits by female adults. This study assessed virulence of twelve entomopathogenic nematode (EPN) isolates to Caribfly in laboratory bioassays as a starting point toward evaluation of management strategies for the fruit-to-soil-dwelling stages of A. suspense in fields infested by Caribfly.
Results:
Inoculation of A. suspensa with 1 ml of ca. 200 IJs (larva)(-1) killed Caribfly at either larval or pupal stage. Pupae were more resistant to EPN infections than larvae. Adult emergence from inoculated pupae in soil microcosms was significantly lower than those observed in filter paper assays. Longest or largest steinernematids suppressed emergence of more adult Caribfly from pupae in soils whereas shorter heterorhabditids were more infectious to Caribfly larvae. The highest mortalities of A. suspensa were caused by exotic nematodes Steinernema feltiae and Heterorhabditis bacteriophora followed by the native Heterorhabditis indica and the exotic Steinernema carpocapsae.
Conclusion:
Entomopathogenic nematodes reduced development of Caribfly larvae and pupae to adult in our bioassays, suggesting that EPNs have potential for biological control of A. suspensa. Future work will assess management strategies, using the virulent EPNs, in orchards infested by A. suspensa.
Entomopathogenic nematodes are considered excellent biological control agents, with greater potential against soil insect pests and pests of cryptic environments. The fruit fly Ceratitis capitata is considered one of the main fruit crop pests worldwide. This insect stays in the soil during a phase of life, where it becomes a target for entomopathogenic nematodes. The objective of this study was to evaluate the pathogenicity and virulence of entomopathogenic nematodes on C. capitata. The bioassays were organized with four replications, containing 10 individuals; 1 mL of a nematode suspension containing 200 IJ/insect was applied. The most virulent isolates against C. capitata larvae were selected and applied at concentrations of 0, 50, 100, 150, 200, 250, 300, 350 and 400 IJ/insect. All isolates were pathogenic for C. capitata. The S. carpocapsae ALL and Heterorhabditis sp. RSC01 isolates were the most virulent against the larval stage, with mortalities of over 85%. As to the pupal stage, isolates Heterorhabditis sp. PI, Heterorhabditis sp. JPM4, H. bacteriophora HP88, S. feltiae and S. glaseri were the best, with mortalities ranging between 35 and 44%.
The history of entomopathogenic nematology is briefly reviewed. Topic selections include early descriptions of members of Steinernema and Heterorhabditis, how only morphology was originally used to distinguish between the species; descriptions of the symbiotic bacteria and elucidating their role in the nematode- insect complex, including antibiotic properties, phase variants, and impeding host defense responses. Other topics include early solutions regarding production, storage, field applications and the first commercial sales of entomopathogenic nematodes in North America. Later studies centered on how the nematodes locate insect hosts, their effects on non-target organisms and susceptibility of the infective juveniles to soil microbes. While the goals of early workers was to increase the efficacy of entomopathogenic nematodes for pest control, the increasing use of Heterorhabditis and Photorhabdus as genetic models in molecular biology is noted.
Infective juveniles of Heterorhabditis shed the enclosing L2 cuticle in the presence of an insect host and expose a large, anterior, terminal tooth which is used to scrape at and rupture the host's cuticle. This may enable easier entry into some insects that are less vulnerable to Neoaplectana species which do not have a terminal tooth.
Entomopathogenic nematodes are soil-inhabiting parasites of insects. Behavioral responses to host and host environmental cues are critical steps in the infection process for some nematode species, such as Steinernema glaseri and Heterorhabditis bacteriophora, of finding, recognizing, and penetrating insects. We investigated the impact of host and host environmental cues on the infectivity of these two nematodes by testing their response to whole and wounded grass roots and gut fluid and hemolymph of Popillia japanica larvae. We also compared the influence of root presence on infectivity. Infective juveniles of both nematode species migrated to whole and wounded grass roots, suggesting that these nematodes may use cues from grass roots and root wounds for host habitat finding. Root presence enhanced the infectivity of S. glaseri, presumably because feeding larvae ingest more nematodes than nonfeeding ones. However, the infectivity of H. bacteriophora was not enhanced by grub feeding. This may due to the weak gut penetration ability of this species. We conclude that the two species respond similarly to host and host environmental cues but achieve infection differently via penetration: S. glaseri possesses superior gut penetration ability, whereas intersegmental areas such as leg and maxilla joints serve as cuticle penetration sites for H. bacteriophora. Copyright 1998 Academic Press.
The olive fruit fly Bactrocera oleae is one of the most serious and economically damaging insects worldwide, affecting the quality and quantity of both olive oil and table olives. Third instar larvae and pupae of several Tephritidae flies were reported to be susceptible to entomopathogenic nematodes (EPNs), but few studies have been carried out on the olive fruit fly. Laboratory assays were conducted to evaluate the susceptibility of B. oleae larvae and pupae to two commercial EPN species, Steinernema feltiae and Heterorhabditis bacteriophora and two indigenous Italian strains of H. bacteriophora and Steinernema carpocapsae. Moreover, an olive assay in the soil was performed to evaluate the capability of EPN strains to enter inside the olive fruits and interact with B. oleae during the pupal stage or the emergence of adults in the winter diapause. The susceptibility assays with B. oleae were performed in well plates, filled with sterile soil (n = 30 for each EPN strain and insect stage). Adult emergence and mortality were recorded daily for 15 days. Dead pupae and adults were dissected to assess nematode infection. The most noteworthy result was obtained with S. feltiae which was able to infect more than 80% of larvae and it killed the pupae inside olive fruits and the adults during their emergence with the same efficacy. Since this Tephritidae fly spends several months in the soil, the use of EPNs, in particular, S. feltiae may represent a promising method to control this pest.
The Field Manual of Techniques in Invertebrate Pathology is designed to provide background and instruction on a broad spectrum of techniques and their use in the evaluation of entomopathogens in the field. The second edition of the Field Manual provides updated information and includes two additional chapters and 12 new contributors. The intended audience includes researchers, graduate students, practitioners of integrated pest management (IPM), regulators and those conducting environmental impact studies of entomopathogens. Although it can function as a stand alone reference, the Field Manual is complementary to the laboratory oriented Manual of Techniques in Insect Pathology and to comprehensive texts in insect pathology.
The Editors have structured the 40 chapters of the Field Manual into 10 sections to provide the tools required for planning experiments with entomopathogens and their implementation in the field. The basic tools include chapters on the theory and practice of application of microbial control agents (MCAs) (Section I), statistical considerations in the design of experiments (Section II), and three chapters on application equipment and strategies (Section III). Section IV includes individual chapters on the major pathogen groups (virus, bacteria, microsporidia, fungi, and nematodes) and special considerations for their evaluation under field conditions. This section sets the stage for subsequent chapters on the impact of naturally occurring and introduced exotic pathogens and inundative application of MCAs. Twenty-three chapters on the application and evaluation of MCAs in a wide variety of agricultural, forest, domestic and aquatic habitats comprise Section VII of the Field Manual. In addition to insect pests, the inclusion of mites and slugs broadens the scope of the book. Most of the chapters in this section include step by step instructions on handling of inoculum, design of field experiments and experimental plots and application and assessment of efficacy of dozens of MCAs. Several of these chapters include supplementary techniques and media for conducting follow up laboratory studies for confirmation of infection, determination of persistence, etc. The three final chapters include: special consideration for evaluation of Bt transgenic plants (Section VIII); resistance to insect pathogens and strategies to manage resistance (Section IX); and guidelines for evaluating effects of MCAs on nontarget organisms (Section X).
Due to uncertainty regarding the future availability of organophosphate and other conventional chemical insecticides, MCAs will play increasingly important roles in IPM. The Field Manual will provide researchers and IPM practitioners with techniques and practical guidance for the study and optimal use of MCAs in a variety of settings.
Bactrocera dorsalis fruit fly is the economically most significant tephritid pest species on Mango, Mangifera indica L., in Benin, and entomopathogenic nematodes (EPNs) represent good candidates for its control in the soil. In this study, the susceptibility of larvae and pupae of B. dorsalis to 12 EPN isolates originating from Benin was investigated. The effect of nematode concentrations (20, 50, 100, 200 and 300 Infective Juveniles (IJs)/. B. dorsalis larva) and of different substrate moisture content (10, 15, 20, 25 and 30% v/w) on B. dorsalis mortality at the larval stage was studied. Also, the reproduction potential inside B. dorsalis larvae was assessed. Our results revealed that the susceptibility of B. dorsalis larvae was significantly different among the 12 tested nematode isolates with H. taysearae isolate Azohoue2 causing the greatest insect mortality (96.09[U+202F]±[U+202F]1.44%). The lowest insect mortality (7.03[U+202F]±[U+202F]4.43%) was recorded with Steinernema sp. strain Bembereke. Significant differences in insect mortality were recorded when EPNs were applied at varying IJs concentrations. A concentration of 100 nematodes of either H. taysearae Azohoue2 or H. taysearae Hessa1 per B. dorsalis larva was enough to kill at least 90% of B. dorsalis larvae. Larvae were less susceptible to nematodes at higher moisture content (25% and 30%). In addition, pupae were less susceptible to nematodes than larvae. Furthermore, the tested nematode isolates were able to reproduce inside B. dorsalis third instar larva with the Heterorhabditis isolates giving the greatest multiplication rate (59577.2 IJs[U+202F]±[U+202F]14307.41).
Turkey is the world’s largest producer of sweet cherries. The European cherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae), is a major pest of sweet cherry crops in Europe and Turkey. The detection of only one larva in the fruit by the processor can result in the rejection of the entire crop of that orchard and/or farm as “wormy” and unmarketable. The main control tactic for R. cerasi is to prevent the females from laying eggs in the fruit. Currently, only a few insecticides are being used, and their application is debatable due to problems with residual ecotoxicity for humans and beneficial organisms. As an alternative to using insecticides for the reduction of adult populations, 4 indigenous entomopathogenic nematode species, Steinernema carpocapsae (Anamur isolate), S. feltiae (Rize isolate), Heterorhabditis bacteriophora (Ekecik isolate), and H. marelatus (Ankara isolate), were bioassayed against last-instar R. cerasi larvae at different temperatures (10, 15, and 25 °C) and nematode concentrations (0, 100, 500, and 1000 IJs/larva). Temperature and nematode concentration had a significant effect on the efficacy of nematode species. S. feltiae was the most virulent species at all temperatures and nematode concentrations. Only S. feltiae showed higher than 40% mortality at low temperatures (10 and 15 °C). At 25 °C, S. feltiae caused 95% mortality, followed by H. marelatus (82%) and H. bacteriophora (76%), at 1000 IJs/larva concentration. Our results indicate that R. cerasi larvae are highly susceptible to entomopathogenic nematode infection. In particular, S. feltiae has high potential for reducing last-instar larval populations, thus decreasing the adult population in the spring.
Infectivity of six entomopathogenic nematode (EPNs) species against Bactrocera oleae was compared. Similar infection levels were observed when third-instar larvae were exposed to infective juveniles (IJs) on a sand-potting soil substrate. When IJs were sprayed over naturally infested fallen olives, many larvae died within treated olives as well as in the soil; Steinernema feltiae caused the highest overall mortality of 67.9%. In addition, three laboratory experiments were conducted to optimize a time period for S. feltiae field application. (1) Abundance of fly larvae inside fallen olives was estimated over the 2006–2007 season with the highest number of susceptible larvae (3mm and larger) per 100 olives being observed during December, 2006. (2) S. feltiae efficacy against fly larvae dropped to the soil post-IJ-application was determined. B. oleae added to the substrate before and after nematode application were infected at similar levels. (3) Effect of three temperature regimes (min–max: 10–27, 6–18, and 3–12°C) corresponding to October through December in Davis, California on S. feltiae survival and infectivity was determined. After 8 weeks, the IJs at the 3–12°C treatment showed the highest survival rate. However, the cold temperature significantly limited S. feltiae infectivity. Our results demonstrate that B. oleae mature larvae are susceptible to EPN infection both in the soil and within infested olives. Being the most effective species, S. feltiae may have the potential to suppress overwintering populations of B. oleae. We suggest that November is the optimal time for S. feltiae field application in Northern California.
Entomopathogenic nematodes of the genera Steinernema and Hetero rhabditis (Nematoda: Rhabditida) have emerged as excellent insect biological control agents. This discipline of insect pathology has
made enormous strides since Glaser’s discovery more than 60 yr ago of nematodes infesting white grubs (1, 2). Recent advances in mass-production and formulation technology, and the discovery of numerous isolates/strains, together
with the desirability of reducing pesticide usage, has resulted in a surge of scientific and commercial interest in these
insect-killing nematodes (3) This has culminated in the commercial availability of many nematode products for use in several mediumand high-value markets
(4). This chapter will briefly review nematode biology, mass production, formulation, quality, application strategy, and field
efficacy.
Infection of cocooned codling moth (cydia pomonella) larvae by the entomopathogenic nematode Steinernema carpocapsae was studied in three field experiments. Factors that varied within or between experiments included method of application, type of substrate containing cocooned larvae, time when nematodes were applied, seasonal effects, and supplemental wetting before or after nematode application. Conventional air-blast sprayer applications of 0.5–5.0 million infective juveniles (IJs)/tree in fall resulted in ca. 30% mortality of larvae in cardboard trap bands, whereas hand-gun application (2 million IJs/tree) produced mortality of ca. 70%. Application in the evening caused higher larval mortality than application in the morning when no supplemental wetting was used after treatments. Morning and evening applications caused equivalent larval mortality when a postwetting treatment was included. In a trial conducted in midsummer, supplemental wetting, either before or after hand-gun application of 1 million IJs/tree, enhanced nematode-produced mortality. Mortality approached 100% if both pre- and postwetting was used. Larvae in exposed cocoons on apple wood were infected at a higher rate (86%) than those on wood in less exposed positions (73%) or in nonperforated cardboard (72%). Mortality rates for larvae in perforated cardboard were intermediate (77%). Application volumes used to deliver nematodes slightly enhanced infection rate of larvae in some substrates but not others. In one trial, parasitism of codling moth by the wasp Mastrus ridibundus (Ichneumonidae) was negatively correlated with nematode infection of codling moth larvae. Dissections showed that ca. 10% of larvae infected by nematodes had been attacked by the wasp.
manual of techniques in insect pathology
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