Search

The green peach aphid, Myzus persicae(Sulzer) (Hemiptera: Aphididae), is an important pest of several worldwide crops. This study evaluated the effects of plant micronutrients (alpha-iron (Fe), zinc sulfate (Zn), copper sulfate (Cu), and manganese sulfate (Mn)) on digestive enzymes, intermediary metabolism, and antioxidant responses of M. persicae reared on bell pepper plants under greenhouse conditions. Results showed that M. persicae reared on Mn-treated plants had the digestive enzymes α-amylase, trypsin, chymotrypsin, and elastase inhibited. Moreover, the aphids fed on Mn-treated plants showed the highest activities of catalase, glucose-6-phosphate dehydrogenase, superoxide dismutase, and peroxidase, and lower increase rate of malondialdehyde. These findings indicate that micronutrients can impact the aphid metabolism, which may aid control strategies against this insect pest. We raise the potential for beneficial use of foliar fertilizer application as a pest management tool that could be further evaluated on a production and economical scale, as well as with other insect pests.

The present study aimed to explore some simple ways to optimize the mass rearing of Cotesia vestalis (Haliday) (Hymenoptera: Braconidae), one of the most important biocontrol agents of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). The effects of host and parasitoid initial densities on the quantity and quality of produced wasps were investigated. In particular, a factorial experiment was established using three different host densities (20, 50, and 100 P. xylostella larvae per cage) in presence of C. vestalis at three different densities (2, 5, and 7 females, with a 24-h exposure) in well-ventilated cages. There was a significant effect of wasp's initial density on the percentage parasitism (measured based on the cocoon and emerged adult wasps); comparatively the greatest percentage parasitism was obtained with five wasps per cage. Initial host density had no significant effects on the percentage parasitism, sex ratio, and larval period, but it influenced the survival rate (measured based on the cocoon and adult emerged) and pupal period of produced wasps, and also percentage host mortality. The density of 20 host larvae was the best in this regard. These findings were discussed in the contexts of optimum mass rearing, life history, and potential of C. vestalis as a biological control agent.