Pupal Mortality Research Articles

Temperature-Dependent Pupation Depth in the Oriental Fruit Fly Bactrocera dorsalis and Its Implications for Biological Control

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a notable agricultural pest that undergoes pupation in the soil. Mortality risk from predation and parasitism decreases as the depth of the pupal location increases from the ground surface, with a one-centimetre increase in depth causing a significant change. Soil properties, such as moisture and hardness, influence pupation depth, but the effect of temperature has not been fully tested. This laboratory study examined whether a biologically important variation in pupation depth (e.g., one centimetre) is caused by naturally experienced temperature variations (20 to 35 °C) in B. dorsalis. The temperature–pupation depth relationship revealed a unimodal pattern, with the deepest pupation occurring at intermediate temperature levels and shallower pupation at the two extreme temperature ranges. Strong quantitative effects were observed, with the highest mean pupation depth of 40.8 mm at 27.5 °C and the lowest mean pupation depth of 15 mm at 35 °C. The observed quantitative effect suggests that temperature can strongly affect pupal mortality from predators and parasitoids by influencing pupation depth. Future studies that reveal the ability of biological control agents to forage underground for pupae at different temperatures are awaited, as this is key information for evaluating the effectiveness of these agents.

Effect of temperature and soil moisture on the infectivity of four species of entomopathogenic nematodes (Steinernema and Heterorhabditis spp.) to fall armyworm, Spodoptera frugiperda (Smith)

Spodoptera frugiperda (JE Smith) is one of the most important lepidopterous pests of maize throughout the word. The implementation of management strategies for this are need of the hour. In this case the use of Entomopathogenic nematodes (EPNs) is feasible because third-instar larvae feed in the leaf whorls of maize, and sixth instar larvae pupate in the soil; these two environments are congenial for the EPNs. But temperature and soil moisture play major roles in EPNs infectivity. Therefore, in the current study, we examined temperature and soil moisture effect on the infectivity of four indigenous EPN species from India, Heterorhabditis indica NBAIIH23, H. bacteriophora NBAIRH75, Steinernema carpocapsae NBAIRS59, and S. abbasi NBAIISa01 against larvae and pupae of S. frugiperda. Present study results showed that both temperature and soil moisture affected the infectivity of H. indica, S. carpocapsae, H. bacteriophora, and S. abbasi. As the exposure time increased, all these four nematodes infectivity to larvae was increased. Six days after inoculation, H. indica caused significantly higher larval mortality (96 %) at 25 °C and 100 % mortality at 28 °C. Whereas, S. carpocapsae caused 100 % mortality at 28 °C, and 76 % mortality at 25 °C. At 32 °C, H. indica and S. carpocapsae caused 90 % and 92 % larval mortality, respectively. As the temperature decreased to 20 °C, the infectivity of both the nematodes decreased. However, H. bacteriophora and S. abbasi caused 68 % and 50 % mortality in larvae at 20 °C, respectively. Compared to other nematodes, H. indica significantly caused higher mortality in pupae at 13 % soil moisture at 28 °C. We conclude that, Heterorhabditis indica and S. carpocapsae can be utilized against S. frugiperda larvae at (25–32 °C), and pupae at (28 °C). These nematodes can also be used against pupae of S. frugiperda at 9–13 % soil moisture content. We also suggest that these EPNs species can be incorporated in the Integrated Pest Management (IPM) for S. frugiperda.

Insecticidal activity of silver nanoparticles synthesised from aqueous leaf extract of Eucalyptus tereticornis on horn flies

An insecticidal efficacy of silver nanoparticles (AgNps) synthesised from aqueous leaf extract of Eucalyptus tereticornis, was carried out against adults, larval and pupal stages of Haematobia flies. In in vitro adulticidal and larvicidal assays the mortality ranged between 30.0 to 67.0 and 5.0 to 75.0 per cent in treated groups after 24 hours at different concentrations, respectively. The inhibition of pupation ranged between 5.0 to 30.0 per cent after 24 hours by dipping method. The lethal concentration values were calculated for all the assays. The probit analysis revealed the significant (p<0.05) effect at different concentrations of AgNPs synthesised from aqueous leaf extract of E. tereticornis on adults, larvae and pupal mortality Keywords: Haematobia flies, silver nanoparticles, in vitro assays

Assessment of larvicidal, growth-suppressing, and developmentaltering bioefficacy of Ageratum houstonianum against Aedes aegypti (L.).

Aedes aegypti is a major vector responsible for spreading dengue, chikungunya, yellow fever, and Zika viruses worldwide. These illnesses have increased globally due to climate and environmental changes. Vector control and management are the principal tactics for combating mosquitoes-borne diseases in the absence of an effective vaccine. The study aimed to ascertain bioactivities of Ageratum houstonianum leaf acetone extract (AhLAE) against Aedes aegypti. Bioefficacy of AhLAE was tested against fourth instar larvae (L4) of Ae. aegypti using standard WHO protocol. The mortality, growth, and development of larvae, pupae and adults were recorded after exposure to the extract. The AhLAE showed larvicidal activity against L4 with LC50 and LC90 values of 401.88 and 691.24 mg/L, respectively. The mortality of the larvae further increased on subsequent days. The AhLAE caused a significant reduction in pupae formation and adult emergence. It also increased the larval duration of L4 and development duration of the pupa formed from the treated L4, indicating its growth-suppressing effects. The impact of the AhLAE was dose-dependent; high concentrations caused reduction in survival and growth of L4. Consequently, the L4-pupal and L4-adult growth indexes decreased. Additionally, the AhLAE induced developmental anomalies in the form of larva-pupa (L-P) intermediates. The study found that the AhLAE exhibited larvicidal, growth-suppressing, and development-altering activities against Ae. aegypti. The findings suggest the potential of AhALE as a natural insecticidal agent for controlling mosquitoes.

Parasitisation activity of Spalangia cameroni and Muscidifurax zaraptor, pupal parasitoids of Musca domestica

AbstractThe house fly, Musca domestica L. (Diptera: Muscidae), is a significant pest in livestock farms and a major concern for both humans and farmed animals due to its ability to transmit over 200 pathogens. The use of pupal parasitoids is a sustainable strategy for controlling this pest. Spalangia cameroni Perkins (Hymenoptera: Spalangiidae) and Muscidifurax zaraptor Girault & Sanders (Hymenoptera: Pteromalidae) are commonly used as biocontrol agents for M. domestica. The objective of this study was to determine the oviposition peak of female parasitoids in relation to their age and the sex ratio of the adult progeny. For both species, 20 fresh M. domestica pupae (24–48 h old) were provided daily to each fertilised female for 14 days, after which the pupae were checked for parasitoid emergence. A control group of 20 pupae without female parasitoids was maintained. The results showed that S. cameroni had a higher overall percentage of parasitisation (57.7%) compared with M. zaraptor (32.4%). The parasitisation ratio of S. cameroni remained almost constant throughout the 14‐day period, whereas that of M. zaraptor decreased drastically after Day 11. Peak oviposition for S. cameroni was on Day 5 with 13 parasitised pupae per female, whereas M. zaraptor parasitised eight pupae per day on 4 days during its peak oviposition period (between Days 3 and 8). The newly emerged parasitoids had a skewed sex ratio towards females: 81% for S. cameroni and 66% for M. zaraptor. The presence of these parasitoid species resulted in fewer new house fly emergences than in the control group, where natural pupal mortality was lower in the absence of parasitoids. These findings may be useful for optimising the mass production and time‐use of the two parasitoid species for the management of house flies in livestock farms.

Effects of elevated CO2 and temperature on the performance of a diet specialized neotropical herbivore and its host plant

AbstractLittle is known about the potential responses of ecologically specialized tropical species to atmospheric change and global warming. In 2 years of greenhouse experiments simulating climate change impacts, we quantified the effects of mean ambient temperature, elevated temperature (Te), current ambient CO2 concentration ([CO2]a), and doubled CO2 concentration ([CO2]e) on biomass, growth rate, and foliar chemistry of the morning glory vine, Camonea umbellata. In addition, we measured the impacts of climate change simulations on the performance and survival of the tortoise beetle, Acromis sparsa, which feeds exclusively on C. umbellata. Full‐sib A. sparsa larval broods were divided into cohorts. Each cohort was placed in one of four temperature‐CO2 controlled chambers and fed leaves grown in their respective treatments. Vines growing in [CO2]e more than doubled their biomass and their leaves expanded faster. The [CO2]a and Te treatments interacted to yield the greatest foliar [C]. Vines in [CO2]e and Te had the greatest C:N ratios, the lowest availability of nitrogen, and highest larval mortality. Whereas pupae were smaller and suffered lower survival in Te, pupal mass and survival increased in both the [CO2]e and Te treatments. Overall, the simultaneous elevation of both [CO2] and temperature caused declines in host quality, larval survivorship, and pupal mortality that were not observed when only one climate factor was altered. Based on this first tropical experimental study, we predict that C. umbellata will benefit from elevation of temperature and atmospheric [CO2] by altering its foliar chemistry to the detriment of its diet‐specialized herbivore enemy.Abstract in Spanish is available with online material.

Consumption of pollen contaminated with field-realistic concentrations of fungicide causes sublethal effects in Bombus impatiens (Hymenoptera: Apidae) microcolonies.

Bumble bees are declining across the globe. The causes of this decline have been attributed to a variety of stressors, including pesticides. Fungicides are a type of pesticide that has been understudied in the context of bumble bee health. As a result, fungicides are often applied to flowering plants without consideration of pollinator exposure. Recent work demonstrates that fungicides have sublethal effects in bumble bees, but little is known about how much fungicide it takes to cause these sublethal effects. To address this gap in the literature, we fed microcolonies of the common eastern bumble bee (Bombus impatiens CressonHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: Apidae) pollen contaminated with a range of fungicide concentrations. We chose these concentrations based on the range of fungicide concentrations in pollen and nectar that were reported in the literature. Results revealed that later-stage pupae and newly emerged males are potentially sensitive to fungicide exposure, showing smaller size and reduced fat reserves at intermediate levels of contamination. Compared to the control, intermediated levels of fungicide-contaminated pollen led to increased pupal mortality and delayed male emergence. Contrary to expectations, higher fungicide levels did not exhibit a linear relationship with negative impacts, suggesting nuanced effects. Because body size and emergence timing are important aspects of bumble bee reproductive behavior, results have implications for mating success, potentially disrupting colony development.

Airway specific deregulation of asthma-related serpins impairs tracheal architecture and oxygenation in D. melanogaster

Serine proteases are important regulators of airway epithelial homeostasis. Altered serum or cellular levels of two serpins, Scca1 and Spink5, have been described for airway diseases but their function beyond antiproteolytic activity is insufficiently understood. To close this gap, we generated fly lines with overexpression or knockdown for each gene in the airways. Overexpression of both fly homologues of Scca1 and Spink5 induced the growth of additional airway branches, with more variable results for the respective knockdowns. Dysregulation of Scca1 resulted in a general delay in fruit fly development, with increases in larval and pupal mortality following overexpression of this gene. In addition, the morphological changes in the airways were concomitant with lower tolerance to hypoxia. In conclusion, the observed structural changes of the airways evidently had a strong impact on the airway function in our model as they manifested in a lower physical fitness of the animals. We assume that this is due to insufficient tissue oxygenation. Future work will be directed at the identification of key molecular regulators following the airway-specific dysregulation of Scca1 and Spink5 expression.

Biology and Morphometrics of Fall armyworm (Spodoptera frugiperda) in Chitwan, Nepal

The Fall armyworm (FAW) Spodoptera frugiperda, native to the Americas, is an important invasive and polyphagous pest threatening cereal production. Abiotic and biotic factors, including climatic uncertainty and insect pests like S. frugiperda, pose threats. Detected in East Africa in 2016 and reported in Nawalpur, Nepal, on May 9, 2019, FAW has led to a 34% decline in maize yields. Studying FAW's biology and morphometrics is crucial for understanding its habitat and ecology, essential prerequisites for adopting integrated management strategies. Biological parameters such as incubation period, larval and pupal duration, pre-oviposition and, oviposition periods, male and female adult longevity, larval and pupal mortality, sex ratio (male: female), and morphometrics of egg, larvae, pupa, and adult were measured. The incubation period (2-3 days), larval and pupal periods (13-18 and 9-12 days) with overall life duration (31-45 days) were recorded in maize. Head capsule width of the first, second, third, fourth, fifth, and sixth instar were recorded as 0.52±0.05, 0.73±0.05, 1.1±0.05, 1.74±0.12, 2.04±0.15, and 2.91±0.23 mm respectively. Mean body length of different larval instars were recorded as 3.33±0.26, 6.92±1.07, 13.11±1.45, 16.82±1.57, 28.68±1.75, and 34.56±1.99 mm for the first, second, third, fourth, fifth, and sixth instar respectively.

MicroRNA-8514-5p regulates adipokinetic hormone/corazonin-related peptide receptor to affect development and reproduction of Plutella xylostella.

Dicer1 plays a crucial role in regulating the development and reproduction of insects. Knockout of Dicer1 causes pupal deformity, low eclosion and low fecundity in Plutella xylostella, but the mechanism behind this phenomenon is not clear. This study aims to identify differentially-expressed genes and miRNAs in the Dicer1-knockout strain (ΔPxDcr-1) and assess their impact on the reproduction and development of P. xylostella. The knockout of Dicer1 affected the expression of genes including the adipokinetic hormone/corazonin-related peptide receptor (PxACPR). The expression of PxACPR was upregulated, and the expression of miR-8514-5p was downregulated in ΔPxDcr-1 of P. xylostella. The dual luciferase reporter assay and pull-down assay showed that miR-8514-5p bound to PxACPR in vitro and in vivo. The expression profiles demonstrated a negative correlation between PxACPR mRNA and miR-8514-5p in different developmental stages of the wild-type strain. Both the miR-8514-5p agomir and double-stranded RNA of ACPR (dsPxACPR) injected into the pre-pupae inhibited the mRNA level of PxACPR, causing high mortality and deformity of pupae, and low fecundity and hatching rate, which were consistent with the phenotype of ΔPxDcr-1. The injection of miR-8514-5p antagomir caused a similar phenotype to the injection of miR-8514-5p agomir. Additionally, the injection of miR-8514-5p antagomir significantly rescued the phenotype caused by dsPxACPR. These results indicate that miR-8514-5p affects the development and reproduction of P. xylostella by regulating PxACPR, and the homeostasis of PxACPR expression is essential for the development and reproduction of P. xylostella. © 2024 Society of Chemical Industry.

Characterization of a Molecular Clone of Deformed Wing Virus B.

Honey bees (Apis mellifera) play a crucial role in agriculture through their pollination activities. However, they have faced significant health challenges over the past decades that can limit colony performance and even lead to collapse. A primary culprit is the parasitic mite Varroa destructor, known for transmitting harmful bee viruses. Among these viruses is deformed wing virus (DWV), which impacts bee pupae during their development, resulting in either pupal demise or in the emergence of crippled adult bees. In this study, we focused on DWV master variant B. DWV-B prevalence has risen sharply in recent decades and appears to be outcompeting variant A of DWV. We generated a molecular clone of a typical DWV-B strain to compare it with our established DWV-A clone, examining RNA replication, protein expression, and virulence. Initially, we analyzed the genome using RACE-PCR and RT-PCR techniques. Subsequently, we conducted full-genome RT-PCR and inserted the complete viral cDNA into a bacterial plasmid backbone. Phylogenetic comparisons with available full-length sequences were performed, followed by functional analyses using a live bee pupae model. Upon the transfection of in vitro-transcribed RNA, bee pupae exhibited symptoms of DWV infection, with detectable viral protein expression and stable RNA replication observed in subsequent virus passages. The DWV-B clone displayed a lower virulence compared to the DWV-A clone after the transfection of synthetic RNA, as evidenced by a reduced pupal mortality rate of only 20% compared to 80% in the case of DWV-A and a lack of malformations in 50% of the emerging bees. Comparable results were observed in experiments with low infection doses of the passaged virus clones. In these tests, 90% of bees infected with DWV-B showed no clinical symptoms, while 100% of pupae infected with DWV-A died. However, at high infection doses, both DWV-A and DWV-B caused mortality rates exceeding 90%. Taken together, we have generated an authentic virus clone of DWV-B and characterized it in animal experiments.

Efficiency assessment of a novel automatic mosquito pupae sex separation system in support of area-wide male-based release strategies

This study provides a comparative analysis of two state-of-the-art automatic mosquito pupae sex sorters currently available: the ORINNO and the WOLBAKI Biotech pupae sex separation systems, which both exploit the sexual size dimorphism of pupae. In Aedes aegypti, the WOLBAKI sex sorter and the ORINNO with a sieve mesh size of 1.050 mm achieved sex separation with female contamination rates below 1%, low pupae mortality rates and high male flight capacity. However, in Ae. albopictus, there was more variability, with female contamination rates above the 1% threshold and pupae mortality reaching 27% when using the ORINNO sorter. On the other hand, the WOLBAKI sorter achieved a male pupae recovery of 47.99 ± 8.81% and 50.91 ± 11.77% in Ae. aegypti and Ae. albopictus, respectively, while the ORINNO sorter with a smaller sieve size achieved male pupae recoveries of 38.08 ± 9.69% and 40.16 ± 2.73% in Ae. aegypti and Ae. albopictus, respectively. This study provides valuable information for researchers and practitioners in the field, assisting in the selection of the most suitable system for mosquito control, management and research programs depending on their specific requirements.

Comparative biocidal effect of BioArt and Crataeva religiosa extracts against the groundnut seed pest Caryedon serratus (OL.) in Senegal

With a view to devising a strategy for protecting groundnut seeds against Caryedon serratus, we tested the biological impact of a product called BioArt made from the leaves of certain plants indigenous to Senegal (Crataeva religiosa, Calotropis procera and Azadirachta indica) and aqueous extracts of Crataeva religiosa on the external forms of C. serratus. The BioArt product caused the greatest mortality in adults. It induced maximum elimination (100%) of adults with the highest dose C1. Extracts of C. religiosa were less effective than BioArt on adults. They induced a maximum effect of 53.33% mortality with the highest dose C1. Females treated with BioArt laid fewer eggs than those treated with aqueous extracts of C. religiosa. With regard to the sex ratio of survivors, a comparative study of the different solutions showed that the BioArt product favoured females, while the C. religiosa extracts were equally distributed between males and females. The ovicidal activity showed almost equal embryonic and larval mortality and a slight difference in pupal mortality (32.41% with BioArt and 47.18% with C. religiosa). Monitoring of surviving eggs showed a lengthening or shortening of the various development times, with larval development, total development and life span being shorter with the BioArt product. The sex ratio was in favour of females for both products.

Compatibility of Entomopathogenic Nematodes with Chemical Insecticides for the Control of Drosophila suzukii (Diptera: Drosophilidae).

The spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a pest that reduces the productivity of small fruits. Entomopathogenic nematodes (EPNs) and chemical insecticides can suppress this pest, but the compatibility of the two approaches together requires further examination. This laboratory study evaluated the compatibility of Steinernema brazilense IBCBn 06, S. carpocapsae IBCBn 02, Heterorhabditis amazonensis IBCBn 24, and H. bacteriophora HB with ten chemical insecticides registered for managing D. suzukii pupae. In the first study, most insecticides at the recommended rate did not reduce the viability (% of living infective juveniles (IJs)) of S. braziliense and both Heterorhabditis species. The viability of S. carpocapsae was lowered by exposure to spinetoram, malathion, abamectin, azadirachtin, deltamethrin, lambda-cyhalothrin, malathion, and spinetoram after 48 h. During infectivity bioassays, phosmet was compatible with all the EPNs, causing minimal changes in infectivity (% pupal mortality) and efficiency relative to EPN-only controls, whereas lambda-cyhalothrin generally reduced infectivity of EPNs on D. suzukii pupae the most, with a 53, 75, 57, and 13% reduction in infectivity efficiency among H. bacteriophora, H. amazonensis, S. carpocapsae, and S. brazilense, respectively. The second study compared pupal mortality caused by the two most compatible nematode species and five insecticides in various combinations. Both Heterorhabditis species caused 78-79% mortality among D. suzukii pupae when used alone, and were tested in combination with spinetoram, malathion, azadirachtin, phosmet, or novaluron at a one-quarter rate. Notably, H. bacteriophora caused 79% mortality on D. suzukii pupae when used alone, and 89% mortality when combined with spinetoram, showing an additive effect. Novaluron drastically reduced the number of progeny IJs when combined with H. amazonensis by 270 IJs and H. bacteriophora by 218. Any adult flies that emerged from EPN-insecticide-treated pupae had a shorter lifespan than from untreated pupae. The combined use of Heterorhabditis and compatible chemical insecticides was promising, except for novaluron.

Greenhouse melon crop protection and production through the compatible use of a parasitoid with endophytic entomopathogenic ascomycetes

This study delves into the compatible use of a parasitoid with multifunctional endophytic Entomopathogenic Ascomycetes (EA) in IPM under greenhouse conditions. The parasitoid Hyposoter didymator was evaluated against Spodoptera littoralis in a multitrophic system with melon plants that were endophytically colonized by one of three EA strains (Metarhizium brunneum [one] or Beauveria bassiana [two]). In the first scenario, plants were inoculated by three different methods, and after infestation with noctuid larvae, the parasitoid was released at a 1:20 ratio. Microbiological and molecular techniques allowed the identification of progressive colonization throughout the whole plant life cycle, and for B. bassiana, approximately 20% of seeds from new fruits were colonized. The parasitoid was shown to be compatible with all strains and application methods, with total mortality rates ranging from 11.1 to 77.8%. Significant lethal and sublethal effects, a decrease in pupal weight and mortality of pupae showing abnormalities and an extension of the immature developmental times were observed for different strain–application method combinations. Additionally, the fungal treatments improved crop growth, as revealed by the significant gains in plant weight. In a second scenario (by inoculating plants with the fungi only by leaf spraying), and after infestation with noctuid larvae, the parasitoid was released at a 1:10 ratio, which revealed the remote fungal effect from the inoculation point and confirmed the compatibility of the parasitoid-EA-based strategy. These findings underscore the compatible use of a parasitoid with endophytic EA for S. littoralis control that can additionally exploit their multifunctionality for sustainable crop production.

Efficacy of entomopathogenic fungi against codling moth, Cydia pomonella (Lepidoptera: Tortricidae)

ABSTRACT Cydia pomonella L. is a highly destructive pest inflicting substantial damage on pome fruits globally. Resistance to chemical pesticides by C. pomonella poses a significant challenge to the effective management strategies. Utilising entomopathogenic fungi (EPF) for the management of insect pests has emerged as one of the promising and environmentally friendly alternatives. Against this backdrop, we conducted laboratory bioassays to assess the efficacy of three EPF, namely Beauveria bassiana (Bals.-Criv.) Vuill., Cordyceps fumosorosea (Wize) and Metarhizium anisopliae (Metschn.) Sorokīn against C. pomonella using three effective concentrations (1 × 104, 1 × 105, and 1 × 106 conidia/ml). Highest larval (98.62 ± 10.00%) and pupal (37.35 ± 2.15%) mortality was observed when treated with B. bassiana while lowest larval (51.55 ± 6.30%) and pupal (17.83 ± 7.28%) mortality was seen in C. fumosorosea. Maximum adult emergence (16.26 ± 3.24) was recorded in C. fumosorosea and the minimum (5.72 ± 0.09) in B. bassiana. LC50 values of C. fumosorosea, M. anisopliae and B. bassiana were 5.482, 2.683 and 1.891 conidia/ml, respectively. All three tested EPF were effective against C. pomonella under controlled laboratory conditions.

Systemic pesticides in a solitary bee pollen food store affect larval development and increase pupal mortality

Solitary bees are often exposed to various pesticides applied for pest control on farmland while providing pollination services to food crops. Increasing evidence suggests that sublethal toxicity of agricultural pesticides affects solitary bees differently than the social bees used to determine regulatory thresholds, such as honey bees and bumblebees. Studies on solitary bees are challenging because of the difficulties in obtaining large numbers of eggs or young larvae for bioassays. Here we show the toxic and sublethal developmental effects of four widely used plant systemic pesticides on the Japanese orchard bee (Osmia cornifrons). Pollen food stores of this solitary bee were treated with different concentrations of three insecticides (acetamiprid, flonicamid, and sulfoxaflor) and a fungicide (dodine). Eggs were transplanted to the treated pollen and larvae were allowed to feed on the pollen stores after egg hatch. The effects of chronic ingestion of contaminated pollen were measured until adult eclosion. This year-long study revealed that chronic exposure to all tested pesticides delayed larval development and lowered larval and adult body weights. Additionally, exposure to the systemic fungicide resulted in abnormal larval defecation and increased mortality at the pupal stage, indicating potential risk to bees from fungicide exposure. These findings demonstrate potential threats to solitary bees from systemic insecticides and fungicides and will help in making policy decisions to mitigate these effects.

Laboratory Evaluation of the Efficiency of The Entomopathogenic Fungus Beauvaria bassiana as a Biological Control Factor Against the Cucurbit Fly, Dacus ciliates

Al-Shweily, B.M., J.B. El-Zidawi and M.J. Hinnawi. 2024. Laboratory Evaluation of the Efficiency of The Entomopathogenic Fungus Beauvaria bassiana as a Biological Control Factor Against the Cucurbit Fly, Dacus ciliates. Arab Journal of Plant Protection, 42(3): 335-339. https://doi.org/10.22268/AJPP-001260 The cucurbit fly, Dacus ciliatus is a major pest which attack a wide range of crops and causes significant losses in agricultural production. Due to the high toxicity of chemical pesticides on human health and the environment, scientists focused on developing alternative safe methods to control this insect, including the use of biocontrol agents. Beauveria bassiana is one of the common fungi used as a bio-control agent. This entomopathogenic fungus was cultivated on Petri dishes containing PDA. The spore suspension of this fungus was prepared using sterilized distilled water, and three concentrations were used: 20×106 , 10×106 and 5×106 spores/ml. The effectiveness of these three concentrations was tested on larvae and pupae of the studied insect. The larval mortality rate ranged from 73.33% at the highest concentration to 33.33% at the lowest concentration used. Pupal mortality reached 66.66% at the highest concentration and 16.66% at the lowest concentration of spore suspension. Mortality rate was directly proportional to the spore suspension concentration of the entomopathogenic fungus. Keywords: Cucurbit fly, agricultural pest, biological control, Dacus ciliates, Beauveria bassiana, entomopathogenic fungi.

Toxicity of Zingiber officinale Nanoparticles Against the Spiny Bollworm, Earias insulana and Their Effects on Some Biological and Histological Aspects

El-Shennawy, R.M. 2024. Toxicity of Zingiber officinale Nanoparticles Against the Spiny Bollworm, Earias insulana and Their Effects on Some Biological and Histological Aspects. Arab Journal of Plant Protection, 42(2): 202-207. https://doi.org/10.22268/AJPP-001237 The toxicity of Ginger extract nano-sized particles (Ginger AgNPs) against the spiny bollworm (Earias insulana) larvae, and its adverse effects on some biological and histological aspects were studied under controlled conditions of 26±1°C and 75±5% RH. LC50 treatment of newly hatched larvae produced larval and pupal mortality rates of 60.00 and 47.06%, respectively, compared to the control treatment (6.33 and 2.00%). Treatment resulted in significant larval and pupal deformity rates (11.00 and 13.51%, respectively) compared to the control (1 and 3%). Ginger AgNPs greatly reduced the adult emergence rate (52.94 %) with a high rate of malformation (11.11%) compared to 89.0 and 0.0 % for the control, respectively. Treatment sharply affected females’ fecundity (69.67%) with an acute decrease in oviposition periods and hatchability rate (66.67%) in comparison to the untreated control. The LC50 of Ginger AgNPs resulted in different histological alternations in the cuticle and midgut compared to the normal structure of the control. Keywords: Ginger, nanoparticles, spiny bollworm, biological changes, histological changes.

Evaluation of the efficiency of entomopathogenic nematodes exposed to different temperatures of vinasse in the control of Stomoxys calcitrans (Linnaeus, 1758) (Diptera: Muscidae).

The sugarcane industry generates byproducts that contribute to the proliferation of Stomoxys calcitrans. An analysis was carried out to verify the efficacy of Heterorhabditis bacteriophora HP88 and H. baujardi LPP7 at different vinasse temperatures to control S. calcitrans larvae. Ten fly larvae were deposited in plastic containers containing four mL of 50% vinasse. Each treatment consisted of 300 EPN/larvae of H. bacteriophora added to the containers and heated at temperatures of 25, 28, 31, 34, 37 and 40 °C. The same treatments were performed using H. baujardi. The treatments were carried out in a BOD incubator at 25 ± 1 °C and 70 ± 10% RH, and each treatment was replicated six times. The treated groups, controls and temperatures showed no statistical differences in terms of larval mortality rate (P=0.8573), percentage of dead pupae (P=0.1782) and adult emergence (P=0.4386). Larval mortality rates of 30% and 14.17% were achieved with H. bacteriophora and H. baujardi, respectively, while the control groups presented 3.89% with H. bacteriophora and 8.61% with H. baujardi. From the standpoint of temperatures, significant differences were found only at 37 and 40 °C for H. baujardi. The highest pupal mortality achieved with H. bacteriophora was 34.17% at 31 °C, while that reached with H. baujardi at 37 °C was 40%. The groups containing H. bacteriophora caused lower adult emergence rates at temperatures of 25, 28, 31 and 34 °C, while H. baujardi caused its lowest emergence rates at 37 and 40 °C. It is concluded that infection occurs in the immature stages of S. calcitrans by EPN when added to 50% vinasse solution at different temperatures and that nematodes caused negative effects on the emergence of fly larvae at varying temperatures.