Search

The Old-World bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae), is a significant threat to crops worldwide and has become resistant to traditional synthetic insecticides. The present study investigated the pathogenicity of the entomopathogenic fungi (EPF) Metarhizium robertsii (Hypocreales: Clavicipitaceae) strain WG-04 or Beauveria bassiana (Hypocreales: Cordycipitaceae) strain WG-10, and an entomopathogenic nematode (EPN) species Heterorhabditis bacteriophora against the second and fourth instar larvae of H. armigera. Both fungal species and H. bacteriophora were evaluated, singly or in combination. After 24 and 48 h post-application of the fungal spores (106 spores/mL), H. bacteriophora was introduced at a rate of 50 infective juveniles/mL, and mortality was observed at 3-, 5-, and 7-days post-treatment. Adult emergence, egg hatching, and percentage pupation were recorded. The integration of both types of biocontrol agents exhibited additive and synergistic interactions in larval stages, and enhanced mortality was recorded when EPF was used in combination with the nematodes. In the individual application of all three biocontrol agents alone, the order of efficacy was H. bacteriophora > B. bassiana > M. robertsii; however, in joint treatments, the increase in mortality and decrease in percentage egg hatching, pupation, and adult emergence was determined to be directly linked to the exposure period of the H. bacteriophora. The results of this study suggest that combining H. bacteriophora with EPF could provide a solid foundation for an economically viable method for managing H. armigera larvae in chickpea fields. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigates the sublethal effects of chlorantraniliprole, an insecticide known for its low toxicity to mammals and selectivity towards non-target organisms, on two significant stored-product pests, Sitophilus oryzae (L.) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Through contact toxicity assays, differences in susceptibility between the two species are observed, with S. zeamais showing higher sensitivity. Subsequent analysis reveals altered mobility behavior in chlorantraniliprole-exposed groups compared with controls, particularly in S. oryzae, which displays reduced number of food approaches and altered locomotion patterns. In contrast, S. zeamais exhibits increased walking time and decreased immobility periods under sublethal concentrations. These findings underscore the importance of considering sublethal effects in understanding the overall impact of chlorantraniliprole on stored-product pest populations. Further exploration into the long-term consequences of sublethal exposure is recommended to enhance pest management strategies. Chlorantraniliprole, an anthranilic diamide insecticide, has emerged as a promising solution for controlling agricultural pests because of its low mammalian toxicity and selectivity towards non-target organisms. This study investigated the sublethal effects of chlorantraniliprole on the mobility behavior of two significant stored-product pests, Sitophilus oryzae (L.) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Contact toxicity assays revealed varying susceptibility levels between the two species, with S. zeamais showing higher sensitivity. Subsequent analysis of mobility behavior, both in the presence and absence of food, indicated significant differences between chlorantraniliprole-exposed and control groups. While S. oryzae exhibited altered locomotion patterns and a decreased number of food approaches at sublethal concentrations, S. zeamais displayed increased walking time and reduced immobility periods. These findings highlight the importance of considering sublethal effects in understanding the overall impact of chlorantraniliprole on stored-product pests. Further research into the long-term consequences of sublethal exposure is warranted to inform more effective pest management strategies in storage. [ABSTRACT FROM AUTHOR]

Simple Summary: Among pests threatening stored food, Rhyzopertha dominica, Tribolium castaneum, Trogoderma granarium, and Sitophilus oryzae are highly dangerous because they cause considerable losses around the world. Taking into account that there is a narrow available spectrum of contact insecticides for the management of stored-grain insects, a laboratory study was conducted to evaluate an insecticidal formulation containing two active ingredients, i.e., thiamethoxam plus chlorantraniliprole, when applied on grains and different surfaces against adults of the aforementioned species. Complete mortality was observed for S. oryzae on all three commodities, for R. dominica on wheat and rice, and for T. castaneum on wheat, 14 days post-initial exposure at the highest dose. At the end of the 90-day storage period, S. oryzae showed the maximum mortality, whereas T. granarium showed the lowest. Bioassays on surfaces revealed that thiamethoxam plus chlorantraniliprole applied on metal killed more adult individuals of all species than on cement, ceramic, or wood. Sitophilus oryzae was found to be the most sensitive on metal, followed by R. dominica, T. castaneum, and T. granarium. An insecticide containing the neonicotinoid thiamethoxam + the diamide chlorantraniliprole was evaluated against adults of Rhyzopertha dominica, Tribolium castaneum, Trogoderma granarium, and Sitophilus oryzae under laboratory bioassays both on freshly treated grain as well as on treated grain stored over 90 days for its persistence in efficacy. In laboratory bioassays, the insecticide was applied on wheat, maize, or rice at four doses, while in persistence bioassays on wheat at the same doses. Mortality and progeny were assessed in both laboratory and persistence bioassays. After 14 days of exposure, S. oryzae exhibited 100% mortality on all three commodities at the highest dose, while R. dominica showed complete mortality on wheat or rice and T. castaneum on wheat. For a period of 90 days, S. oryzae exhibited 42.69% mortality, followed by R. dominica (35.26%), T. castaneum (27.08%), and T. granarium (18.63%) at the highest dose. Progeny was successfully suppressed in all cases of complete mortality in laboratory bioassays and for S. oryzae for 90 days in persistence bioassays. Laboratory trials were also performed on plywood, concrete, ceramic tile, and steel at one dose. The highest mortality was observed on steel, followed by concrete, ceramic tile, and plywood for all insect species tested. This study demonstrates that thiamethoxam + chlorantraniliprole is effective against the tested species depending on exposure, storage period, surface, commodity, and dose. [ABSTRACT FROM AUTHOR]

This study determined the efficacy of Beauveria bassiana (Bals. -Criv.) Vuill., Metarhizium anisopliae (Metchnikoff) Sorokin, and diatomaceous earth mixed with abamectin (DEA) alone and in their combinations for the integrated management of larvae and adults of Tribolium castaneum (Herbst) from three field populations of Pakistan (Multan, Rawalpindi, and Rahim Yar Khan) and one laboratory population (Faisalabad). Treatments were applied on three surfaces, namely, viz. steel, concrete, and jute bags, implementing two application methods, dusting and spraying. The combined treatments were more effective in comparison with single treatments for both larvae and adults. Overall, the highest mortality rates were recorded in the Faisalabad population, followed by the Rehaim Yar Khan, Rawalpindi, and Multan populations. Progeny production was suspended 21 days after exposure to the combined treatment of DEA and both fungi in all populations except Rawalpindi. Larvae were found to be more susceptible than adults in all treatments and intervals. Dusting was more efficient than spraying for both larvae and adults and for all the populations studied. The present study provides a wholistic understanding of the impact of different factors on the success of the combined treatments using DEA and entomopathogenic fungi, supporting their use as surface treatments. [ABSTRACT FROM AUTHOR]

Background: Mortality caused by various pyrethroids, and neonicotinoids has been studied for stored-product insects in the past, yet limited information exists on the sublethal effects they can induce to Oryzaephilus surinamensis. In the current study, the sublethal effects of deltamethrin, λ-cyhalothrin, α-cypermethrin, etofenprox, and the mixture of acetamiprid with d-tetramethrin and piperonyl butoxide on the mobility of O. surinamensis in the presence or the absence of a food source was investigated., Results: Lethal concentrations (LCs) were lower for deltamethrin, α-cypermethrin, and λ-cyhalothrin (LC 10  = 0.000233, 0.000211, and 0.000271 mg active ingredient (a.i.) cm -2 , LC 30  = 0.000413, 0.000398, and 0.000447 mg a.i. cm -2 , respectively), followed by etofenprox, and the mixture of acetamiprid with d-tetramethrin and piperonyl butoxide (LC 10  = 0.00228 and 0.003267 mg a.i. cm -2 , LC 30  = 0.00437 and 0.01188 mg a.i. cm -2 , respectively). Deltamethrin and λ-cyhalothrin negatively impacted adult walking behavior, increasing stop durations compared to controls. Adults exposed to LC 10 and LC 30 of λ-cyhalothrin, and LC 30 of deltamethrin exhibited prolonged periods on their backs compared to the remaining treatments and the controls. The α-cypermethrin LC 30 -exposed adults exhibited significantly shorter walking and stopping durations than controls but demonstrated prolonged climbing on the arena walls compared to adults exposed to the remaining a.i. and the control. A similar trend was observed for etofenprox., Conclusions: Under sublethal concentrations, λ-cyhalothrin and deltamethrin increased stop intervals and reduced the duration of climbing attempts of O. surinamensis versus α-cypermethrin. These findings advance comprehension of the underexplored sublethal impacts of the tested a.i. on O. surinamensis adults, holding potential for leveraging insecticide-induced behavioral effects to enhance warehouse pest management. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)