Adding non-crop plants enhances parasitoid fitness on potato plants, but not pest densities

Conservation biological control (CBC) aims to enhance pest regulation/suppression by intentionally attracting, retaining, and promoting the fitness and effectiveness of natural enemies. Due to carbohydrate sources being highly limited in agroecosystems, providing alternative carbohydrate sources (i.e., nectar sugars, starches) can enhance the survival, fecundity, and effectiveness of natural enemies. Under laboratory conditions, we analyzed five flowering non-crop plant species in habitat management on the longevity, egg load, and reproductive performance of the parasitoid, Aenasirus bambawalei Hayat (Hymenoptera: Encyrtidae), a key natural enemy of mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae). Moreover, we measured the influence of the flowering candidates on the host preference and population growth of P. solenopsis. All five flowering non-crop plant species, Fagopyrum esculentum (Polygonaceae), Tagetes erecta (Asteraceae), Vicia faba (Fabaceae), Lobularia maritima (Brassicaceae), and Coriandrum sativum (Apiaceae) promoted the longevity and egg load of A. bambawalei when compared with water only. However, only the females fed on F. esculentum, V. faba, and L. maritima produced 16% and 13% higher total offspring and female offspring than on water, respectively. None of these five non-crop plant species increased the population of mealybugs on crop plants or in the overall system (non-crop plants + crop plants), and there was no significant difference in their abundance across the five different plant combinations. All five flowering candidates positively affected the longevity and/or reproductive capabilities of A. bambawalei without causing an increase in the population of mealybugs on crop plants.