A preventive strategy for the control of aphids in sweet pepper using lacewings and micrococcinelid beetles

Aphids are a serious threat to sweet pepper crops. Due to increasing aphid resistance to insecticides and rising demand for pesticide-free products, pest management is currently based on biological control programs. However, growers often face economic losses because these programs have limited success, largely due to poor establishment of natural enemies when aphid populations are low. This study aimed to evaluate new natural enemies for early-season aphid control. Two candidates were selected to be used against the aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae): the micrococcinellid Scymnus interruptus (Goeze) (Coleoptera: Coccinellidae) and the brown lacewing Micromus variegatus (Fabricius) (Neuroptera: Hemerobiidae). Two studies were conducted to assess their potential as aphid biocontrol agents. Firstly, different alternative food sources that might help for supporting their establishment in the absence of aphids were tested. Secondly, in a greenhouse experiment conducted in walk-in cages, natural enemies were released under preventive conditions (long aphid absence). Their establishment, complementarity, and effectiveness were evaluated during 5 weeks, after periodical low aphid infestations. Our results exposed that supplemental food sources must be provided for the survival of M. variegatus when aphids are absent in the crop. However, S. interruptus could survive in absence of aphids in the presence of sweet pepper flowers for a long period. Our greenhouse trial showed S. interruptus provided better aphid control than M. variegatus but the best results came from combining both species. Overall, our study demonstrated the potential of M. variegatus and S. interruptus as preventive biocontrol agents against aphids in sweet pepper crops.