Preliminary studies on the parasitism rate of larval parasitoids of the diamondback moth (Plutella xylostella) L. (Lepidoptera: Plutellidae) in the Ashanti region of Ghana

Abstract

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is the most important pest of the brassicas worldwide. Over the years, management of this pest has largely relied on conventional insecticides, with well-documented negative impacts. Biological control using indigenous natural enemies is a promising way to manage the pest while reducing the use of synthetic insecticides. However, due to the negative impact of synthetic insecticides on beneficial insects, the number of natural enemies in the agroecosystem is often below the levels that may have significant pest reduction. Here, we assessed the range and parasitism rates of the larval parasitoids of P. xylostella in the Ashanti Region of Ghana. On the whole, one hymenopteran endo-parasitoid species, Cotesia plutellae, was identified in the P. xylostella larval samples. In all, the percentage of field parasitism of P. xylostella larvae ranged between 11% and 23%. Given the percentage of parasitism in this preliminary study, we are of the view that there is potential in relying on endemic parasitoids to biologically manage P. xylostella if conditions in agroecology are improved to encourage the survival of these beneficial insects.