Integrated Pest Management Programs Research Articles

Comparing the Performance of Hyphantria cunea (Lepidoptera: Arctiidae) on Artificial and Natural Diets: Feasibility of Mass-Rearing on Artificial Diets.

In China, Hyphantria cunea (Drury) is an invasive phytophagous pest; it attacks nearly all species of defoliated trees. To develop integrated pest management programs (IPM) for H. cunea, we need to ensure the availability of insects by mass-rearing them on artificial diets under laboratory conditions. This study compared the growth characteristics, nutritional indices, growth indices, and digestive enzyme activity of insects reared on Pterocarya stenoptera C.DC (Fagales: Juglandaceae), the Chinese wingnut, and an artificial diet. We also investigated the correlation between diet components and growth indices using principal components analysis and Pearson correlation analysis. We found that mass-rearing of H. cunea on an artificial diet was feasible. It led to a shorter developmental period, with heavier larvae and pupae than natural diets. The principal components analysis indicated that the growth indices and α-Amylase were significantly positively associated with PC1, which explained 82.45% of the total data variability. Pearson correlation analysis showed a significant correlation between digestion, absorption parameters, and growth. Developing a mass-rearing program to produce H. cunea on an artificial diet will be valuable for improving IPM strategies. Understanding the mechanism of the responses of phytophagous insect populations to anthropogenic diet regulation can provide new ideas and methods for pest control.

Control efficacy and joint toxicity of metaflumizone mixed with chlorantraniliprole or indoxacarb against the fall armyworm, Spodoptera frugiperda.

The fall armyworm (FAW), Spodoptera frugiperda is the main destructive pest of grain crops, and has led to substantial economic losses worldwide. Chemical pesticides are the most effective way to manage FAW. Here, a laboratory test using an artificial diet-incorporated assay was conducted to determine the toxicity of five insecticides and the joint effect of the binary combination insecticides to FAW larvae. A field plot test using foliar spray was carried out to assess the control efficacy of metaflumizone mixed with chlorantraniliprole or indoxacarb against FAW. The bioassay results showed that metaflumizone had a stronger insecticidal effect than indoxacarb toward FAW larvae. Furthermore, the mixture of metaflumizone and chlorantraniliprole in a volume ratio of 3:7 had the strongest synergistic effect against FAW, with a co-toxicity coefficient (CTC) of 317.18. The best synergistic effect for mixtures of metaflumizone and indoxacarb was observed at a 1:9 volume ratio, with a CTC of 185.98. However, there was an antagonistic effect of metaflumizone mixed with emamectin benzoate and with lufenuron, because the co-toxic factor was less than -20 at volume ratios of 8:2 and 9:1, respectively. According to the results of the field trial, metaflumizone mixed with chlorantraniliprole or indoxacarb at a 50% reduction of the application rate can effectively control FAW with efficacy ranging from 77.73% to 94.65% 1-7 days postapplication. Overall, our findings suggest that metaflumizone and its binary combination insecticides can be utilized in FAW integrated pest management programs. © 2022 Society of Chemical Industry.

Integrating Trap Cropping and Entomopathogenic Nematode Foliar Sprays to Manage Diamondback Moth and Imported Cabbage Worm

Diamondback moth (DBM), Plutella xylostella, and imported cabbage worm (ICW), Pieris rapae, are destructive pests of crucifers worldwide. Although several insecticides are effective against ICW, pesticide management against DBM is challenged by insecticide resistant populations. The objective of this study was to explore the potential of integrating foliar sprays of the entomopathogenic nematode (EPN) Steinernema feltiae with trap cropping using kai choi (Brassica juncea) planted as an intercrop for the management of DBM and ICW. Four 2 × 2 (trap crop × EPN) factorial designed field trials were conducted with 2 trials on head cabbage (Brassica oleraceae var capitata) and 2 on kale (Brassica oleraceae var acephala). In the first head cabbage trial, trap cropping reduced DBM abundance by 46% and ICW abundance by 73%. Leaf damage by DBM and ICW were reduced by 45% and 33%, respectively. In the second head cabbage trial, DBM populations were reduced by 19% whereas ICW was reduced by 65%. No effects were observed on leaf damage. Trap cropping suppressed DBM abundance by 50% and DBM leaf damage by 19% in the first kale trial. No significant effects were observed on ICW. In the second kale trial, trap cropping reduced ICW leaf damage by 13%. In the first head cabbage trial, adding EPN foliar sprays further reduced DBM populations in plots with trap crops and ICW in plots without trap crops. In the second kale trial, EPNs suppressed DBM populations entirely. No effects from EPNs were observed in the second head cabbage trial or the first kale trial. It is concluded that trap cropping with kai choi did not improve the efficacy of EPN foliar sprays consistently. EPNs were most successful at suppressing DBM and ICW populations when the average pest pressure was below 0.5/plant whereas trap crops worked more effectively at insect populations above 0.5/plant. Although the use of trap cropping reduced pest abundance and leaf damage, the weight of head cabbage and kale was lower when planted 30 cm or closer to kai choi plants. This was resolved by leaving a distance of 60 cm between cash and trap crops. With further optimization, the use of trap cropping and EPN foliar sprays can be beneficial to an integrated pest management program to control DBM and ICW in cruciferous crops.

Impact of covert infections with an RNA virus on the susceptibility of Spodoptera exigua to natural enemies

Integrated Pest Management (IPM) programs are alternatives to classical pest control through the application of chemical insecticides. IPM goal is to maintain pest populations below economically injurious levels minimizing the use of chemical insecticides. In recent years, research on insect viromes has led to the discovery of many novel viral pathogens in insect pests, some of them producing covert infections that do not cause evident symptoms. However, the impact that these viruses have on the action of natural enemies employed in IPM programs is still unknown. Spodoptera exigua iflavirus 1 (SeIV1) is an RNA virus commonly found in field populations of Spodoptera exigua. In this work, we have analysed the possible impact of those viral infections on the activity of different natural enemies used for the control of this pest. Specifically, we have studied the effects of SeIV1 on susceptibility to entomopathogenic nematodes, fungi, bacteria, and parasitoids. Infections with SeIV1 showed to be compatible with the nematode Steinernema carpocapsae as the infection did not affect the susceptibility or production of new juveniles. Moreover, they are also compatible with the fungus Metarhizium brunneum as the mortality of S. exigua larvae was not affected by the viral infection. Interestingly, infections with SeIV1 increase the susceptibility to Bacillus thuringiensis formulation and increase the mortality caused by the parasitism of Hyposoter didymator. In summary, our results show that the four natural enemies tested are not negatively affected by SeIV1 and their action remains similar or enhanced by the covert infections with this iflavirus.

Potential of UV-C for management of two-spotted spider mites and thrips in Florida strawberry.

Major pests of Florida strawberry (two-spotted spider mites, Tetranychus urticae Koch; chilli thrips, Scirtothrips dorsalis Hood; and western flower thrips, Frankliniella occidentalis Pergande) are difficult to manage using only conventional chemical control. Previous research has demonstrated high mortality of T. urticae eggs after exposure to ultraviolet B (UV-B) light. Additionally, ultraviolet C (UV-C) light has been shown to suppress powdery mildew in strawberry at doses between 85 and 200 J m-2 with no damage to the plant. Therefore, UV-C may also have the potential to be used as an integrated pest management tool for arthropod pests of strawberry. The objectives of this study were to: (i) determine the effect of UV-C on T. urticae, S. dorsalis, and F. occidentalis natural populations in open-field strawberry; and (ii) determine the effect of UV-C on T. urticae egg hatch after application in open-field strawberry. Field studies were conducted during the 2019-2020 and 2020-2021 strawberry seasons in Florida, USA. Four treatments were compared: (i) foliar application of spinetoram in response to natural pest pressure; (ii) application of UV-C 200 J m-2 twice a week; (iii) application of UV-C 350 J m-2 twice a week; and (iv) a non-treated control. In the field trials, suppression of T. urticae was observed at 350 J m-2 in 2020-2021. In the other field trials, no effect was observed due to low natural infestations. No negative impact on yield was observed from UV-C applications. UV-C shows promise as a component of an integrated pest management program for T. urticae in strawberry. © 2022 Society of Chemical Industry.

A low-toxicity baiting program precipitates collapse of Argentine ant and ant-associated hemipteran pest populations in commercial citrus

The Argentine ant, Linepithema humile Mayr (Hymenoptera: Formicidae), disrupts biological control agents which induces population outbreaks of honeydew-producing hemipteran pests infesting agroecosystems. A multi-season liquid baiting program was evaluated for control of L. humile and ant-associated hemipteran pests in six commercial citrus orchards in southern California. Ant activity in treated trees fell by 96% within three months of treatment and was, on average, 95% lower in treated plots than untreated plots across the 18-month study period. Ant control resulted in the near elimination of hemipteran pest populations on trees in treated plots. Pre- and post-treatment estimates indicated that hemipteran pest infestation of twigs, flush, and fruit decreased by 97, 84, and 99% one year after treatment, respectively. Furthermore, cumulative infestation frequency was 10 times lower and cumulative colony size was 5 times lower on treated trees than control trees across the final year of study. Examining individual hemipteran pest species, the mean infestation rate by Diaphorina citri Kuwayama (Hemiptera: Liviidae) was 75% lower, Coccus hesperidum L. (Hemiptera: Coccidae) 95% lower, Planococcus citri Risso (Hemiptera: Pseudococcidae) 98% – 100% lower, and Aonidiella aurantii Maskell (Hemiptera: Diaspidae) 70 – 80% lower in treated trees relative to untreated trees. A surge in generalist predator activity and parasitism following ant bait deployment appear to be the driving forces behind the marked decrease in pest infestation observed in treated trees. Results underscore the importance of L. humile control for integrated pest management programs targeting ant-associated hemipteran pests in commercial citrus.

First record of Delphastus argentinicus Nunenmacher (Coccinellidae: Serangiini) as a predator to whitefly in cassava crops

Cassava crops hold high agricultural importance in Paraná State, Brazil. However, cassava root production is adversely impacted by pests. Aleyrodids, in particular, cause great damage to cassava fields, necessitating better knowledge of predators found in these agroecosystems and novel biological control strategies for integrated pest management. This study reports the first occurrence of the predatory lady beetle Delphastus argentinicus Nunenmacher, preying on all life stages of whiteflies in cassava fields. Given the economic and social importance of cassava crops in Brazil and the deleterious potential of aleyrodid species, it is recommended to conduct behavioral and bioecological studies assessing the application of D. argentinicus as a biocontrol agent in integrated pest management programs.

Laboratory evaluation of chlorfenapyr for control of carmine spider mite, Tetranychus cinnabarinus on tomato in Botswana

The efficacy of chlorfenapyr was studied in the laboratory against the carmine spider mite on tomato. The acaricide was applied at five concentrations, including the label rate, separated on a log 10 scale. Each treatment was replicated three times. LC50 and LC90 values were determined by probit analysis during different periods after application and were used to determine the efficacy of the acaricide. LC90 values were 0.52, 0.50, 0.44 and 0.38 ml/L when treatments were evaluated at 24, 48, 72 and 96 hours after treatment. This indicated that chlorfenapyr was highly effective against T. cinnabarinus adults. Probit line slopes were 8.15, 6.96, 5.50 and 2.96 at 24, 48, 72 and 96 hours after application. This indicates a fast change in spider mite mortality with increasing in acaricide concentrations. This study found that chlorfenapyr can be used to effectively control T. cinnabarinus under Botswana conditions, especially in combination with other control methods in integrated pest management programs.

Chemical Characterization of Clove, Basil and Peppermint Essential Oils; Evaluating Their Toxicity on the Development Stages of Two-Spotted Spider Mites Grown on Cucumber Leaves.

The two spotted spider mite (TSSM), Tetranychus urticae Koch, is a cosmopolitan mite. It rapidly reproduces and can develop resistance to chemical pesticides. This study aims to evaluate the toxicity and acaricidal activity of three essential oils from basil, clove, and peppermint against T. urticae reproduction, which is grown on three cucumber cultivars, Chief (SC 4145), Raian (CB898), and Toshka (SC 349), under laboratory conditions at 27 + 3 °C and 70 + 5% RH. GC-MS characterized the volatile oils of basil, clove, and peppermint. Methyl cinnamate, eugenol, and menthol were the main essential oils in basil, clove, and peppermint, respectively. The results indicated significant differences in the duration of development between T. urticae feeding on the three cucumber cultivars (p ≤ 0.05), including eggs, protonymph, and deutonymph time. The Toshka (SC 349) cultivar recorded the lowest developmental time. The longevity period exhibited the same trend with non-significant differences between Raian (CB898) and Toshka (SC 349). Moreover, the lethal concentration (LC50) and LC90 values in tested essential oils (EOs) showed that clove EOs were the most toxic. In contrast, basil and peppermint EOs were the least effective, and immature stages were more sensitive to EOs than adult stages. The infected Toshka (SC 349) discs treated with essential oils and abamectin under in vitro conditions indicated that clove oil is comparable to abamectin regarding its effect on the egg numbers (18.7 and 17.6 egg), immature development time, longevity, life span, and life cycle (20.6 and 20.8 days) of T. urticae. We conclude that the resistant cultivation of cucumber plants can be recommended in integrated pest management programs. The most effective of the tested oils, clove EOs, should be used as alternatives to pesticides to control T. urticae in the protected cultivation of cucumbers.

Recent Advances and Challenges in Implementing IPM Programmes in the Entomological Context of Indian Agriculture

Integrated pest management (IPM) programmes are based on using multiple methods to maintain nuisance insects below tolerant levels in crop fields. Recent advances in IPM in developed countries have incorporated biological pesticides, microbial products, semiochemicals, and beneficial insects, but few of such programmes have been successfully implemented in developing countries, such as India. Semiochemicals play critical roles as signals in various interspecific and intraspecific interactions between insects and plants, and among interacting insects, plants, and microbes. In India IPM programmes have included mechanical, chemical, cultural, and biological management strategies. However, among these methods, biological management has its own limitations. Indian IPM scientists mostly work on individual crops, assessing damage severity by specific nuisance arthropods and the efficacy of particular management measure. However, very few government institutions or commercial companies are engaged in developing and commercializing either biological pesticides or semiochemicals. Government institutions mostly focus on research on pheromones of the pestiferous Lepidoptera and Coleoptera. Developing IPM programmes requires a clear understanding of crop-plant development, biology and population dynamics of the nuisance organisms, and the chemical and molecular interactions between the two. It also necessarily requires local knowledge of available, prevalent management tactics. Moreover, the IPM programmes have not been widely adopted in developing countries due to lack of proper knowledge and training farmers in efficient IPM practices, the need for more of human labour, and the complexity of IPM practices, all of which impede on the effective implementation of IPM programmes. In this article, we recapture the historical development of IPM efforts in India and ask whether this concept remains suitable to the present-day challenges in crop production. In this review, more specifically, those factors identified as obstacles to the more widespread adoption of IPM and ways of overcoming such barriers are discussed.

Which artificial larval diet is better for Ceratitis capitata (Diptera: Tephritidae) rearing?

BackgroundThere is an increasing demand for biological agents for integrated pest management programs, requiring a constant supply of insects in terms of quantity and quality. In this context, the development of insect-rearing methods and quality control parameters are essential in order to provide best-quality and economic viability products. The medfly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important species of fruit flies in several fruit-producing areas of Brazil, being massively reared in many countries for Sterile Insect Technique (SIT) programs. To achieve mass production scale, suitable larval diets are necessary for medfly rearing at laboratory conditions. Therefore, the objectives of this study were to determine the best artificial larval diet and the respective larval density for C. capitata on diets based on corn flour (CF), sugarcane bagasse (SB), and lyophilized carrot powder (CP), considering biological parameters of quality control and economic viability.ResultsBased on the obtained results and although all diets produced quality pupae according to FAO/IAEA/USDA standards, the SB artificial diet promoted better results in the number of larvae, larval weight, number of pupae, and pupal weight, in comparison with CF and CP diets, as well as being the most economically viable. The optimal larval densities on CF, SB, and CP diets were, respectively, 0.5, 2.0, and 1.0 mL of eggs/kg of diet.ConclusionsThe diet that was most suitable for insect yield and economic viability was the SB diet, followed by the CF and CP diets, in this order.

Which Protein Source is Best for Mass-Rearing of Asian Weaver Ants?

The Asian weaver ant (Oecophylla smaragdina) is sometimes used as a biocontrol agent against pests in tropical agriculture as part of integrated pest management programmes. However, the effectiveness of weaver ants as a predator depends on the abundance and activity of colonies in naturally occurring populations. Mass-rearing is a method that could be useful both for getting lots of colonies and for maximising colony growth and aggressiveness. The diet of mass reared weaver ants potentially impacts their growth rate and behaviour. In this study, we investigate the effect of four common commercial protein diets (mackerel, tuna, cricket and mealworms) on O. smaragdina colony growth and aggressiveness during mass-rearing over a two-month experimental study at the Smart Research Institute, Riau, Indonesia. Colonies fed on mackerel, the cheapest protein source, and mealworm were able to grow significantly larger than those fed on tuna, even though colonies fed with mackerel showed the lowest amount of mass intake of protein food. In contrast, colonies fed with crickets (the diet with the greatest proportion of protein) had the greatest aggression index against experimentally placed bagworms (a common pest in oil palm plantations), with their aggression being significantly greater than that for mackerel-fed colonies. Taken together, our results show that there are trade-offs between different protein diets for weaver ant colonies in mass rearing facilities. Protein diet can be chosen depending on whether colony growth rate, colony aggressiveness, or price is the main factor driving decisions.

Silicon as a plant defense inducer against the two-spotted spider mite Tetranychus urticae (Trombidiformes: Tetranychidae) invasion on strawberry

Strawberry is an essential strategic crop in Egypt that has been severely affected by the two-spotted spider mite (TSSM). A field trial was conducted to investigate the effects of the foliar application of two silicon (Si) forms, oligomeric silicic acid (OSAB®) and potassium silicate (Silica K®), on strawberry resistance against TSSM invasion. Two Si concentrations (2 mL L−1 and 4 mL L−1) were applied with two-sprays strategy. The foliar application of both Si forms (4 mL L−1) and spray sessions caused a significant reduction in the number of TSSM adults, nymphs, and eggs compared to the control group. Both Si forms achieved a marked increase in the activity of defense-related enzymes (peroxidase, catalase, and polyphenol oxidase) and the elevation of the total protein, and phenol contents in Si-treated plants as compared to the control group. There was a significantly negative correlation between the Si leaf content and TSSM population density. Our results suggest that Si could be easily incorporated into TSSM integrated pest management programs in strawberry as an inducer of plant defense.

Comparison of Monitoring Systems and Temporal Activity Patterns for Spotted-Wing Drosophila (Diptera: Drosophilidae): Implications for Integrated Pest Management

Abstract Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a significant, global invasive species first confirmed in the United States in 2008. Since the first detection in Minnesota in 2012, D. suzukii rapidly became a major economic pest of berry crops in the state. Effective monitoring of adult D. suzukii populations is a crucial aspect of developing integrated pest management (IPM) programs for at-risk crops. Drosophila suzukii monitoring research was conducted in 2016 and 2017 to better understand the effectiveness of two commercially available trapping systems for early detection of adults in spring and how mean trap catches compared over time. In addition, using the Scentry trap, we assessed the impact of lure age on trap performance. Finally, a study was conducted to better understand the diurnal activity pattern for adult D. suzukii under Minnesota summer conditions. Results comparing the trapping systems indicated each system varied in its ability to detect first catch of D. suzukii but that both commercial traps/lures were effective. The lure age study showed that lures can be changed less frequently than initially suggested. Temporal activity studies, as measured by trap catch via Scentry traps, indicated that adult D. suzukii demonstrated a crepuscular activity pattern in raspberry and blueberry. The results of these studies should benefit growers as they continue to fine-tune fruit IPM programs for D. suzukii.

Immune Responses of Rhynchophorus ferrugineus to a New Strain of Beauveria bassiana

Evaluating a novel fungal strain’s pathogenicity to important pests and their involved immune responses may give crucial data on a broad scale for future use in pest management strategies. Date palms are mostly destroyed by invading populations of red palm weevils; thus, developing natural biopesticides for them requires a comprehensive screening program of plant secondary metabolites. In this research, we examined the pathogenicity of a new strain of Beauveria bassiana on an important agricultural pest, Rhynchophorus ferrugineus, by measuring the relative activity of defensive enzymes and detoxifying enzymes in certain larval instars. Our findings reveal that the B. bassiana strain may infect the instars of R. ferrugineus, and its pathogenicity to the larvae steadily increases as the spore concentration increases. Seven days after inoculation, the LC50 (the median lethal concentration) of B. bassiana was 490.42 × 105 and 2974.47 × 108 spores/mL for the second and fourth instar R. ferrugineus, respectively, and the LC50 of B. bassiana for each R. ferrugineus instar decreased with infection time, indicating a significant dose effect. Infected R. ferrugineus larvae of the second instars showed considerable changes in the activity of both protecting and detoxifying enzymes (peroxidase, catalase, superoxide dismutase, Cytochrome P450, glutathione S transferase (GST), and esterase) as infection time progressed. In addition, R. ferrugineus larvae that were infected with B. bassiana had enzyme activity that persisted from 24 to 48 h, which was much longer than in the control group. Lethality of B. bassiana resulted in elevated expressions of GST, Esterase, and Cytochrome P450 responsive genes. In conclusion, the results of this research indicate that B. bassiana may be utilized as a bio-insecticide to suppress young larvae of R. ferrugineus in an integrated pest management program.

A full-length transcriptome and gene expression analysis of three detoxification gene families in a predatory stink bug, Picromerus lewisi.

The predatory stink bug P. Lewisi shows potential for Integrated Pest Management programs for controlling Lepidoptera pest insects in crops and forests. The importance of this insect for biological control has stimulated several studies into its biology and ecology. However, P. lewisi has little genetic information available. In the present study, PacBio single-molecule real-time (SMRT) sequencing and Illumina RNA-seq sequencing technologies were used to reveal the full-length transcriptome profiling and tissue-specific expression patterns of P. lewisi. A total of 12,997 high-quality transcripts with an average length of 2,292 bp were obtained from different stages of P. lewisi using SMRT sequencing. Among these, 12,101 were successfully annotated in seven public databases. A total of 67 genes of cytochrome P450 monooxygenases, 43 carboxylesterase genes, and 18 glutathione S-transferase genes were identified, most of which were obtained with full-length ORFs. Then, tissue-specific expression patterns of 5th instar nymphs were analyzed using Illumina sequencing. Several candidate genes related to detoxification of insecticides and other xenobiotics as well as the degradation of odors, were identified in the guts and antennae of P. lewisi. The current study offered in-depth knowledge to understand the biology and ecology of this beneficial predator and related species.

Pathogenicity of Beauveria bassiana PfBb and Immune Responses of a Non-Target Host, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Simple SummaryIn this study, we tested the pathogenicity of Beauveria bassiana PfBb on the important agricultural pest Spodoptera frugiperda (Lepidoptera: Noctuidae) by determining the relative activities of protective enzymes and detoxifying enzymes in different larval instars. Our results show that the B. bassiana PfBb strain could infect all six larval instars of S. frugiperda, and its virulence to S. frugiperda larvae gradually increased with an increase in spore concentration. Furthermore, the activities of protective enzymes (i.e., catalase, peroxidase, and superoxide dismutase) and detoxifying enzymes (i.e., glutathione S-transferases, carboxylesterase, and cytochrome P450) in S. frugiperda larvae of the first three instars infected with B. bassiana PfBb changed significantly with infection time, but such variations were not obvious in the fifth and sixth instars. These findings laid the foundation for further research on the mechanism by which B. bassiana controls S. frugiperda.Exploring the pathogenicity of a new fungus strain to non-target host pests can provide essential information on a large scale for potential application in pest control. In this study, we tested the pathogenicity of Beauveria bassiana PfBb on the important agricultural pest Spodoptera frugiperda (Lepidoptera: Noctuidae) by determining the relative activities of protective enzymes and detoxifying enzymes in different larval instars. Our results show that the B. bassiana PfBb strain could infect all six larval instars of S. frugiperda, and its virulence to S. frugiperda larvae gradually increased with an increase in spore concentration. Seven days after inoculation, the LC50 of B. bassiana PfBb was 7.7 × 105, 5.5 × 106, 2.2 × 107, 3.1 × 108, 9.6 × 108, and 2.5 × 1011 spores/mL for first to sixth instars of S. frugiperda, respectively, and the LC50 and LC90 of B. bassiana PfBb for each S. frugiperda instar decreased with infection time, indicating a significant dose effect. Furthermore, the virulence of B. bassiana PfBb to S. frugiperda larvae gradually decreased with an increase in larval instar. The activities of protective enzymes (i.e., catalase, peroxidase, and superoxide dismutase) and detoxifying enzymes (i.e., glutathione S-transferases, carboxylesterase, and cytochrome P450) in S. frugiperda larvae of the first three instars infected with B. bassiana PfBb changed significantly with infection time, but such variations were not obvious in the fifth and sixth instars. Additionally, after being infected with B. bassiana PfBb, the activities of protective enzymes and detoxification enzymes in S. frugiperda larvae usually lasted from 12 to 48 h, which was significantly longer than the control. These results indicate that the pathogenicity of B. bassiana PfBb on the non-target host S. frugiperda was significant but depended on the instar stage. Therefore, the findings of this study suggest that B. bassiana PfBb can be used as a bio-insecticide to control young larvae of S. frugiperda in an integrated pest management program.

Biological impact, oxidative stress and adipokinetic hormone activities of Agrotis ipsilon in response to bioinsecticides

The use of biological control products enhances the reduction of harmful pressures on the environment caused by the use of conventional pesticides. Therefore, this study aims to evaluate the toxicity of eight bioinsecticides on the black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) to understand the relationships between insecticide exposure and insect response at the individual and population levels. The bioassay results showed that emamectin benzoate had high toxicity against A. ipsilon second instar larvae with an LC<sub>50</sub> of 0.007 (mg/L). Sublethal concentration (LC<sub>30</sub>) of emamectin benzoate, spinosyn group and Bacillus thuringiensis formulation (Dipel 2X) had significantly prolonged pupal period. In addition, emamectin benzoate significantly decreased the number of eggs laid per female (135.3 ± 6.919) compared with the control treatment. Thus, the formulation of chlorfenapyr showed a 1.26-fold reduction in hatching rate. Meanwhile, the activities of oxidative stress enzymes (catalase, superoxide dismutase, lipid peroxidase, and glutathione reductase) were significantly affected due to exposure to sublethal concentration. Changes in adipokinetic hormone (AKH) transcriptional regulation were detected via SQ-PCR via using cDNA synthesized from mRNA isolated from treated A. ipsilon larvae. The results showed a higher transcription rate of AKH in spinotram-treated larvae with a 1.42-fold increase over untreated larvae. Our results provide useful information for integrated pest management programs for A. ipsilon by using bioinsecticides.

Impact of aqueous extracts of Cassia occidentalis, Eucalyptus camaldulensis and Hyptis suaveolens on the entomofauna and the seed yield of Gossypium hirsutum at Boklé (Garoua, Cameroon)

There is a frightening decline in the population pollinators around the world due to the over usage of synthetic pesticides, leading to the directly reduce of plant production. Plant extracts with insecticidal properties could be eco-friendly alternatives to synthetic pesticides in maintaining the pollinator population and the diversity of the ecosystem. The impact of aqueous extracts of Cassia occidentalis L., Eucalyptus camaldulensis Dehnh. and Hyptis suaveolens L. was investigated on the entomofauna and the seed yield of Gossypium hirsutum L. cotton. The study was carried out in RCBD, four times replicated: 3 extracts x 1 standard synthetic insecticide (TEMA) x 1 control x 4 groups of flowers (group 1: flowers free to insect visits, group 2: flowers protected from insects using gauze bags, group 3: protected flowers and opened exclusively to Amegilla sp. and group 4: protected flowers opened from time to time without any visit of insect). Gossypium hirsutum was found to be visited by the insects belonging to five orders, 10 families and 18 species. Amegilla sp.1 and Apis mellifera were the major pollinators during the rainy and dry seasons, respectively. The number and quality of seeds visited exclusively by Amegilla sp.1 were significantly improved by H. suaveolens extract. During the dry season, E. camaldulensis and H. suaveolens extracts as well as the standard insecticide improved the number of seeds and the percentage of normal seeds harvested from the flowers allowed to be visited by insects; that was probably due to their insecticidal effects which protected plants from pest damage. Therefore, aqueous extracts of E. camaldulensis and H. suaveolens are good candidates for incorporation in integrated pest management programs to minimize the risk of synthetic pesticides to pollinators, hence to increase the yield and the quality of seeds.

Response of Doru luteipes (Dermaptera: Forficulidae) to insecticides used in maize crop as a function of its life stage and exposure route.

The present study aimed to evaluate insecticide toxicity to Doru luteipes (Scudder), a major predator of maize pests. Lethal and sublethal effects were assessed on nymphs and adults exposed to the insecticides through contact (maize leaves) and ingestion (prey eggs) routes. Tested insecticides included a biopesticide (Spodoptera frugiperda multiple nucleopolyhedrovirus, SfMNPV), modern (flubendiamide and metaflumizone), and older neurotoxins (imidacloprid + β-cyfluthrin). The imidacloprid/β-cyfluthrin mix was highly toxic (100% mortality) to the predator, regardless of the exposure route and predator stage. Metaflumizone caused mortality higher than 95% and 45% of nymphs and adults. Flubendiamide and SfMNPV were the least toxic insecticides, not differing from the untreated control in any of the assessed endpoints. Adult tibial length did not differ among treatments. Metaflumizone impaired egg consumption by nymphs and walking distance of adult D. luteipes. Overall, the insecticides caused a more pronounced effect on D. luteipes nymphs than on adults and were more toxic by the contact route. From these findings, flubendiamide and SfMNPV are safer for D. luteipes and should head insecticide choice in integrated pest management programs in maize.