CONICET | Buscador de Institutos y Recursos Humanos

Alpaida veniliae is one of the most abundant spider species of the orb web weaver guild, inaddition to its high abundance, its biological and ecological attributes point out the importanceof conservation this predator as a natural enemy of many several soybean crop pests. Butexcessive use of pesticides plays a negative role for them. Insect growth regulator (IGR) hasproven to be effective and selective for natural enemies. The selectivity of the insecticidemethoxyfenocide (IGR) we evaluated on A. veniliae, negatively affecting survival, webbuilding, prey consumption, mating, and female productive capacity. Non-mortality wasregistered along the 96 h post treatment. Prey consumption was not significantly differentbetween treatments. Females treated with methoxyfenozide began web building 9 days laterthan the control (31.7% failed to build). Egg-sacs and egg-masses number abnormal(desiccated, rotten) in each oviposition, well as total abnormal ovipositions were significantlygreater in the methoxyfenozide treatment than in control. Fecundity and fertility were adverselyaffected by methoxyfenozide. Through dissection of ovaries of methoxyfenozide-treatedspiders, it was observed that the distribution of mature oocites was random with respect to thecontrol. Mean oocyte diameter was significantly lower in the methoxyfenozide treatment 15days after mating. Mature oocytes of control spiders exhibited large granules in the cytoplasm,ribosomes, endoplasmic reticulum, lipidics bodies, vitellinic membrane, and chorionicmembrane; with methoxyfenozide, they showed a substantial cell disruption and many inactivecells. This study provides new insights into the side effects of insecticide methoxyfenozide onbiological aspects of the spider A. veniliae.

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