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Stenoma catenifer (Lepidoptera: Depressariidae), the avocado seed borer, represents a major phytosanitary threat in Andean avocado production systems. Egg parasitoids of the genus Trichogramma constitute promising biological control agents for this pest; however, their field-level compatibility with agrochemicals commonly used in avocado orchards remains largely uncharacterized. This study evaluated the side effects of 13 commercial pesticide formulations on Trichogramma exiguum (Hymenoptera: Trichogrammatidae) under two complementary exposure scenarios: (1) residual contact toxicity on adults and (2) susceptibility of parasitized Ephestia kuehniella (Lepidoptera: Pyralidae) eggs, following International Organisation for Biological Control IOBC/WPRS standardized methodology. Corrected adult mortality was assessed at 1 h and 24 h post-exposure, while parasitism expression at the pupal stage, adult emergence rate, and developmental time were recorded for preimaginal stages. At 24 h, abamectin, acephate, lambda-cyhalothrin, and metalaxyl caused 100% adult mortality (harmful), whereas potassium soap and hexythiazox were classified as moderately harmful. In Bioassay 2, potassium soap completely suppressed parasitism expression and adult emergence (0%), while neem extract showed no significant reduction relative to the water control. Developmental time to adult emergence ranged from 9.7 to 12.0 days across treatments, with no statistically significant differences among them. These results indicate that neem extract and the adjuvant dispersant are broadly compatible with T. exiguum, whereas neurotoxic insecticides and potassium soap are incompatible under both exposure scenarios. These findings provide an evidence-based compatibility hierarchy to guide the strategic integration of chemical inputs and augmentative biological control in avocado integrated pest management programs.
Noboa et al. (Wed,) studied this question.