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

Simple Summary: Functional plants can be deployed at the field, farm, and landscape scale, where they are beneficial to natural enemies, thus contributing to improved pest control. To explore how noncrop plants can augment the biological control of pests, this study aimed to assess how basil (Ocimum basilicum L.) (Lamiales: Lamiaceae), as a functional plant, affected the lacewing Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae) in the laboratory and greenhouse. The results showed that in the presence of the target prey (peach aphid; Myzus persicae (Sulzer)), both the vegetative and flowering stages of basil enhanced C. pallens (early-age) fecundity and longevity as compared to a control treatment in the laboratory. Similarly, lacewing colonization patterns were modulated by the basil planting density and spatial arrangement in the greenhouse. Under high density intercrop basil arrangements, C. pallens colonization rates were the highest, the populations persisted longer in the crop, and the aphid numbers declinedmore rapidly. Thiswork showed howbasil enhanced the fitness attributes of a generalist predatory lacewing and benefitted aphid biological control in a short time. It can inform the development of economically soundmanagement strategies to attain pest control withminimuminputs. 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 (Ocimum basilicum L.) (Lamiales: Lamiaceae) affected the biological control of aphids by the predatory lacewing Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae). In the presence of the target prey (peach aphid; Myzus persicae (Sulzer)), both the vegetative and flowering stages of basil enhanced C. pallens longevity and (early-age) fecundity as compared to a control treatment. When basil plants were established near aphid infested eggplants (Solanum melongena L.), the C. pallens 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, C. pallens 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.

Automated summary

This study assessed the impact of basil on aphid biological control by predatory lacewings, revealing that basil enhanced lacewings' longevity and fecundity, and modulated their colonization patterns. High density intercrop basil arrangements led to increased lacewing colonization rates, longer population persistence, and faster aphid decline, highlighting the potential of functional plants in enhancing pest control in agricultural systems.