Abstract
New plant protection strategies focus on minimizing chemical pesticide use and increasing their compatibility with biological control agents. The objective was to evaluate the side-effects of glyphosate, diflubenzuron, malathion, tebuconazole and triflumuron (at 720, 45, 400, 150 and 20 g ai ha−1, respectively), pesticides authorized for soybean crops in Brazil, on the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae) reared on Anticarsia gemmatalis (Lepidoptera: Noctuidae). The emergence and female numbers produced per P. elaeisis female were higher in A. gemmatalis pupae from caterpillars fed an artificial diet treated with glyphosate. However, emergence was lower than 50% when the caterpillars were fed on soybean leaves treated with glyphosate offered ad libitum (3–5 times). Palmistichus elaeisis died before parasiting A. gemmatalis pupae treated with malathion. Diflubenzuron reduced the P. elaesis sex ratio in the second generation. Tebuconazole and triflumuron did not cause side-effects on this parasitoid. A continuous exposure to glyphosate by the host may lead to side-effects on P. elaeisis emergence, but its moderate use is acceptable for this parasitoid. Diflubenzuron had severe transgenerational side-effects. Tebuconazole fungicide and triflumuron insecticide are compatible with P. elaeisis in sustainable integrated pest management (IPM) programs, while malathion can not be included in them.
Highlights
The significant contribution of parasitoids to pest control is due to their high host specificity[5], but generalist ones can contribute to the control of arthropod pests
The objective of this study was to evaluate the side-effects of diflubenzuron, glyphosate, malathion, tebuconazole and triflumuron, pesticides used for soybean crops, on the performance of P. elaeisis fed with A. gemmatalis pupae from caterpillars exposed to these pesticides
Anticarsia gemmatalis caterpillars were fed an artificial diet or soybean leaves treated with glyphosate and/or tebuconazole to obtain the pupae
Summary
The significant contribution of parasitoids to pest control is due to their high host specificity[5], but generalist ones can contribute to the control of arthropod pests. Palmistichus elaeisis Delvare and LaSalle, 1993 (Hymenoptera: Eulophidae) is a generalist and gregarious endoparasitoid of Coleoptera and Lepidoptera pupae[7] This parasitoid is released to control Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae) in soybean crops[8], pesticides are still widely used in this crop[6]. Anticarsia gemmatalis (Lepidoptera: Noctuidae) pupae treated with them These pesticides are authorized for use in soybean cultivation in Brazil. Salto de Pirapora, ® ® São Paulo, Brazil; Malathion Chab , Cheminova Brasil Ltda, Goiânia, Goiás, Brazil. Parasitoids and predators can be exposed directly to pesticides during pesticide applications or, more commonly, indirectly by host hemolymph and contaminated prey tissues[11] In this way, these insects remain exposed to sublethal doses for longer time periods than lethal doses[19]. The exposure to pesticides does not necessarily result in the death of natural enemies[20], but their effects may comprise the development, longevity and fecundity of these insects, as well as behaviors involved in mobility, foraging for hosts (or prey) and mates[17]
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