Endophytic colonization of cauliflower by Aspergillus flavus and Aspergillus niger reduces performance and host preference in tobacco caterpillar, Spodoptera litura

Abstract

Microbial biological control agents are garnering widespread interest for managing insect pests, and their usage in agriculture offers a viable alternative to synthetic insecticides. In this study, cauliflower plants (Brassica oleracea var. botrytis L., Brassicaceae) inoculated with endophytic fungi Aspergillus flavus (Link) (Eurotiales) and Aspergillus niger (van Tieghem) (Eurotiales) isolated from Acacia arabica (Willd) (Fabaceae) were used to assess their insecticidal potential against Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) larvae. Inoculation of cauliflower with both endophytes resulted in significant mortality, reduced adult emergence, prolonged development period, and negatively affected the reproductive potential of S. litura. The nutritional physiology of the larvae fed on the endophyte-infected leaves was significantly affected. The relative growth and consumption rates of the S. litura larvae decreased as compared to the control. The fungal endophytes suppressed the activity of some digestive and detoxifying enzymes. The larvae fed on leaves inoculated with fungal endophytes showed a significant decrease in total hemocyte count, as well as in the activity of phenoloxidase and lysozyme. This study showed that artificial inoculation of plants with fungal endophytes would help in reducing pest incidence and thus could be integrated in future pest management programs.