Side effects of bioinsecticides used to control Tuta absoluta

Integrated Pest Management (IPM) programs may include pesticide applications, thereforeassessing their potential side effects on biocontrol agents is of primary importance for implementingIPM. Bracon nigricans (Hymenoptera: Braconidae) is a larval ectoparasitoid of Lepidoptera specieswhich was recovered on the South American tomato pinworm, Tuta absoluta (Lepidoptera:Gelechiidae), in various Western Palaearctic countries and is a potential biocontrol agent of this pest.We assessed acute toxicity and sublethal effect on fertility of six bioinsecticides, used for controllingT. absoluta, on B. nigricans. The tested chemicals were abamectin, azadirachtin, borax salt plus citrusessential oil, Bacillus thuringiensis var. kurstaki, emamectin benzoate and spinosad. The wasps wereexposed for three days to dried pesticide residues on tomato sprouts, at two time intervals after initialtreatment. Mortality was daily checked and the number of adult parasitoids emerged was recorded toassess the effects on reproduction. These data were used to calculate reduction coefficients and thepesticides were classified according to the IOBC toxicity categories. The obtained data were thendiscussed with the results of a previous study, conducted with the same experimental setting, on thegeneralist predator Orius laevigatus (Heteroptera: Anthocoridae). The insecticides greatly differed intheir toxicity as well as in their persistence and the effects varied also between the two biocontrolagents. Our findings would help to optimize future use of the tested insecticides in IPM and organicfarming, notably by preventing the possible side effects of the tested pesticides on biological controlagents, both naturally present and artificially released. Furtermore, these results stress the need tocareful select the chemicals for efficient IPM programs on tomato crops.