The potential of Clonostachys rosea as a biolarvicide against Anopheles gambiae

conidia/mL for washed conidia. Fungal culture supernatant retained over 95% of its activity upon autoclaving, suggesting a temperature stable non-proteinaceous mycotoxin is responsible for larvicidal activity in the supernatant. Conidia were readily ingested, remained in the gut lumen, and did not germinate or pass to the ectoperitrophic space nor the hemocoel. UV and heat-killed conidia retained larvicidal activity (24.5% and 35.4% mortality, respectively), demonstrating that no active secretion of toxins, fungal growth, or infection is required for killing mosquito larvae. However, autoclaving conidia abolished larvicidal activity (96.9% mortality), suggesting that larvae may not be killed via a mechanical mechanism, such as occlusion. Instead, our data demonstrate that C. rosea conidia kill An. gambiae larvae via the passive release of intracellular mycotoxins and have potential as a fungal biolarvicide to control An. gambiae populations.