Optimizing the Use of Basil as a Functional Plant for the Biological Control of Aphids by <i>Chrysopa pallens</i> (Neuroptera: Chrysopidae) in Greenhouses.

Abstract

Effective biological control agents that can provide sustainable pest control need to be researched in further detail; functional plants (or non-crop insectary plants), in particular, are garnering increased research interest. Much remains to be learned as to how non-crop plants can augment biological control in greenhouse systems. In this study, we combined laboratory and greenhouse assays to assess the extent to which basil (<i>Ocimum basilicum</i> L.) (Lamiales: Lamiaceae) affected the biological control of aphids by the predatory lacewing <i>Chrysopa pallens</i> (Rambur) (Neuroptera: Chrysopidae). In the presence of the target prey (peach aphid; <i>Myzus persicae</i> (Sulzer)), both the vegetative and flowering stages of basil enhanced <i>C. pallens</i> longevity and (early-age) fecundity as compared to a control treatment. When basil plants were established near aphid infested eggplants (<i>Solanum melongena</i> L.), the <i>C. pallens</i> colonization rate improved by 72-92% in the short-term. Lacewing colonization patterns were modulated by the basil planting density and spatial arrangement (i.e., perimeter planting vs. intercropping). Under high density intercrop arrangements, <i>C. pallens</i> colonization rates were highest, its populations persisted longer in the crop, and the aphid numbers declined more rapidly. Our work shows how basil enhanced the key fitness attributes of a generalist predatory lacewing and benefitted aphid biological control in a greenhouse setting.