Host-parasitoid dynamics of Pieris brassicae and Cotesia vestalis: sustainable pest control in cruciferous crops.

Pieris brassicae (Linnaeus, 1758) (Lepidoptera: Pieridae), commonly known as the cabbage butterfly, is a major herbivorous pest causing significant damage to Brassica crops, which are widely cultivated for edible parts and economic uses such as oilseed production. Conventional chemical-based pest control methods pose risks to environmental and human health, prompting interest in sustainable alternatives like biological control using parasitoids. This study evaluated crop damage by P. brassicae larvae and the potential of the larval parasitoid Cotesia vestalis (Haliday, 1834) (Hymenoptera: Braconidae) in managing pest populations. Larvae and fertilized eggs of P. brassicae were collected and reared on four host diets (cabbage, cauliflower, turnip, and generic brassica) under controlled laboratory conditions. Larval growth, feeding behavior, and development were assessed, along with a feeding index for dietary efficiency. Parasitisation was introduced by exposing larvae to adult C. vestalis, and host-parasitoid interactions were statistically analyzed using one-way ANOVA and regression models. Results revealed that larvae had the highest feeding preference and weight gain on brassica, while turnip-fed larvae consumed the least. Parasitisation by C. vestalis significantly suppressed larval development, with a strong correlation between parasitisation rates and reduced host fitness. These findings highlight C. vestalis as a promising biological control agent for P. brassicae, offering an effective and eco-friendly alternative to chemical pesticides. Further research should focus on optimizing C. vestalis mass-rearing protocols and release strategies tailored to diverse Brassica cropping systems to promote sustainable pest management.