Impacts of azadirachtin and chlorantraniliprole on the developmental stages of pirate bug predators (Hemiptera: Anthocoridae) of the tomato pinworm Tuta absoluta (Lepidoptera: Gelechiidae)

Conservation of natural enemies is an important approach for enhancing biological control. Selective insecticides have become important for managing arthropod pests, and the prospects for their use in combination with biological control agents are increasing. In addition, progress has been made in recent decades to develop reduced-risk insecticides that have novel modes of action and, therefore, likely to have a minimum non-target effect. In this study, we use a series of laboratory bioassays to investigate the impact of two reduced-risk insecticides, azadirachtin and chlorantraniliprole, on the egg, nymph and adult stages of two predatory pirate bugs, Amphiareus constrictus (Stal) and Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae), important predators of the tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). All three stages were exposed to the label recommended field rate of these two insecticides, which is indicated for the control of T. absoluta. Neither azadirachtin nor chlorantraniliprole affected the mortality of adult predators or their egg hatchability, suggesting a safe acute toxicity for these stages. However, azadirachtin and chlorantraniliprole negatively decreased the capacity of predator nymphs to reach the adult stage. This decrease can directly affect the size of the predator population in the next generation, and may undermine the biological control of pests such as T. absoluta. In general, our results call for caution when using these reduced-risk insecticides in integrated programs of chemical and biological control of this pest.A conservação de inimigos naturais é urna estratégia importante para o controle biológico de insetos-praga. O uso de inseticidas seletivos também tem sido importante para o manejo de insetos-praga, e a prospectiva de ter seu uso combinado com agentes de controle biológico tem ganhado espaço últimamente. Além disso, tem ocorrido um grande progresso nas ultimas décadas com relação ao desenvolvimento de inseticidas de risco reduzido que apresentam novos modos de ação, e possívelmente uma menor chance de causar efeitos nao-alvo. No presente trabalho, nós conduzimos uma série de bioensaios em laboratorio para investigar o impacto de dois inseticidas de risco reduzido, azadiractina e clorantraniliprole, sobre os estádios de ovo, ninfa e adulto de dois predadores hemípteras, Amphiareus constrictus (Stal) and Blaptostethus pallescens Poppius (Heteroptera: Anthocoridae), que são importantes inimigos naturais da traça do tomate Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). Todos os três estádios foram expostos à dose de campo destes dois inseticidas, a quai é recomendada para o controle de T. absoluta. Tanto azadiractina como clorantraniliprole nao afetaram a mortalidade dos predadores adultos ou a eclosão de seus ovos para qualquer espécie, sugerindo a ausencia de uma toxicidade aguda para estes estádios de desenvolvimento. Porém, azadiractina e clorantraniliprole afetaram negativamente a capacidade de ninfas dos predadores alcançarem o estádio adulto. Essa redução na capacidade das ninfas alcançarem o estádio adulto pode afetar diretamente o tamanho da população de predadores na próxima geração, um impacto que poderia reduzir o controle biológico de pragas como T. absoluta. Em géral, nossos resultados sugerem a necessidade de cautela quando usar inseticidas de risco reduzido em programas que visam integrar o controle químico e biológico desta praga

Investigation of the lethal and behavioral effects of commercial insecticides on the parasitoid wasp Copidosoma truncatellum

Copidosoma truncatellum (Hymenoptera: Encyrtidae) is an important parasitoid wasp of the soybean looper, Chrysodeixis includens, but its effectiveness can be severely curtailed by the application of certain insecticides. Therefore, to identify insecticides that are potentially compatible with C. truncatellum, the lethal and behavioral effects of nine chemicals used to control the soybean looper were evaluated for their toxicity to the wasp. Chlorantraniliprole, chlorfenapyr, flubendiamide, and indoxacarb were the least toxic insecticides to the parasitoid, resulting in mortalities of less than 25%. In contrast, cartap, deltamethrin, and methomyl caused 100% mortality, and acephate and spinosad caused 76% and 78% mortality, respectively. At least one of the detoxifying enzymes (monooxygenase, glutathione S-trans- ferase, and/or esterases) may be involved in the mechanisms underlying the selectivity of chloran- traniliprole, chlorfenapyr, flubendiamide, and indoxacarb for the parasitoid based on the results for the insecticide plus synergist treatment. Changes in the behavioral patterns (walking time and resting time) of the parasitoid were found with exposure to acephate, flubendiamide, indoxacarb and methomyl, but behavioral avoidance was not observed. Our results indicate that the insecticides chlorantraniliprole and chlorfenapyr are the most suitable for inclusion in integrated pest management strategies for the control of C. includens