Side-effects of pesticides on the generalist endoparasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)

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.