The effect of emamectin benzoate on two parasitoids, Aphidius colemani Viereck (Hymenoptera: Braconidae) and Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), used in pepper greenhouses

Aphidius colemani Viereck and Eretmocerus mundus Mercet are two of the most representative parasitoids used as biological control agents (BCAs) primarily against aphids and whiteflies, respectively. The macrocyclic lactone emamectin benzoate (4”-deoxy-4”-methylamino-4”-epiavermectin B1 benzoate), an insecticide derived from the avermectin family of natural products, is being developed for controlling lepidopteran pests on a range of vegetable and other crops in Europe. The objective of this study was to determine the level of compatibility of the insecticide emamectin benzoate with A. colemani and Er. mundus, which are used in greenhouse vegetable production in southeastern Spain. Trials were conducted under commercial greenhouses to assess the effect of 1-, 3- and 7-day-old residues of emamectin benzoate at the highest recommended concentration (14.25 mg L-1) on the population dynamics of the parasitoids. A. colemani, although released at higher rates than those commercially used, only reached low densities (less than 1 adult per plant), without significant differences among control plots and those treated with the compound. On the contrary, a natural infestation by native Er. mundus occurred and this trial can be considered as a direct-spray trial. Neither adult population nor parasitism on emamectin benzoate treated plots differed significantly from the control. Therefore, emamectin benzoate residues did not diminish A. colemani population densities if applied 1 day before the introduction of the arthropod (exposure to 1-day old residues). Similarly, emamectin benzoate was compatible with Er. mundus if a direct spray application was used on developed populations.