The side‐effects of pesticides used in integrated production of peaches in Brazil on the egg parasitoid Trichogramma cacoeciae Marchal (Hym., Trichogrammatidae)
The side-effects of six pesticides used on peaches in Brazil were tested on the hymenopteran egg parasitoid Trichogramma cacoeciae using four laboratory tests: (a) adult parasitoid exposure to fresh pesticide residue on glass plates (worse case); (b) direct spray of host eggs enclosing the parasitoid egg, larvae or pupae (less-exposed life stages); (c) exposure of adults to pesticide residues on plant leaves at different intervals after application (persistence); (d) Dose–response pesticide exposures of adults on glass plates. Two dose rates were used: (1) The highest recommended field dosage (FD) and (2) the predicted initial environmental concentrations (PIEC). The results showed that the preparations greatly differed in their initial toxicity and persistence. The insecticide Valient® (methoxyphenozide) and the fungicide Venturol® (dodine) were considered harmless to T. cacoeciae adults as they fell into the class 1 category according to the guidelines of the International Organization for Biological Control (IOBC) when parasitoids were directly exposed to chemical residues. The insecticide/acaricide Assist® (mineral oil) was slightly harmful at the rate of PIEC 0.4 (40% of FD) and moderately harmful at FD. Pesticides in the categories harmless and moderately harmful can be considered for use in integrated pest management (IPM). The fungicide/acaricide Kumulus DF® (sulphur) and the insecticides Dipterex® 500 (triclorfon) and Lebaycid® 500 (fenthion) were harmful at both concentrations. In the persistence test, Assist® was short lived and therefore may in special cases (i.e. reduced direct contact) be considered for use in IPM, but Kumulus® DF, Dipterex® 500 and Lebaycid® 500 constantly reduced parasitism between 77 and 100% and were rated as persistent (more than 30 days). The direct spray of parasitized host eggs at intervals after parasitism showed that Assist® and Kumulus® DF were harmless to the parasitoid egg, larvae and pupae within the host eggs. Dipterex® 500 was slightly harmful when sprayed one day after parasitism (parasitoid egg) and moderately harmful to the other two stages (larvae and pupae). Lebaycid® 500 was harmful to the parasitoid egg and larvae and moderately harmful to the pupae. The dose–response test showed that Kumulus® DF and Dipterex® 500 were toxic to T. cacoeciae . Kumulus® DF was harmful from 1 PIEC 0.4 to 0.125 PIEC 0.4 dosages and was slightly harmful with 0.0625 PIEC 0.4 dosage. Dipterex® 500 was harmful to T. cacoeciae in all the dosages tested.