Direct and Indirect Infection Effects of Four Potent Fungal Isolates on the Survival and Performance of Fall Armyworm Larval Parasitoid Cotesia icipe
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sustainability
Abstract
Fall armyworm (FAW), Spodoptera frugiperda, has recently invaded Africa, where it is seriously threatening food security. Current management methods rely heavily on synthetic insecticides
which are harmful to humans, the environment, and non-target beneficial insects. Cotesia icipe was
recently identified as a major FAW-associated indigenous parasitoid causing a high parasitism rate
on the pest in Kenya. Previous studies have demonstrated the efficacy of Metarhizium anisopliae ICIPE
7, ICIPE 41, ICIPE 78, and Beauveria bassiana ICIPE 621 against FAW. However, limited information is
available on the interactions between these potent isolates and C. icipe. This study, therefore, assessed
direct and indirect infection effects of these fungal isolates on C. icipe, induced 2nd instar FAW
mortality, and parasitism rates of the infected C. icipe. Results showed that when C. icipe were directly
exposed to dry conidia of the fungal isolates, ICIPE 7 and ICIPE 41 caused the highest (100%) C. icipe
adult mortality seven days post-exposure. Both isolates also induced the highest FAW larval mortality
of 55% and 53%, respectively. ICIPE 78 recorded the highest parasitism rates after direct infection. In
the indirect exposure (fungal-infected FAW larvae exposed to the parasitoid), 1 × 109
conidia mL−1
recorded high C. icipe adult and FAW 2nd instar mortalities for all fungal isolates. This study provides:
an important baseline for effective fungal-based biopesticide development that could also be used in
augmentative biological control. However, further studies are warranted to assess the performance
of C. icipe in combination with these potent biopesticides in the field.
Description
Research Article
Keywords
Beauveria bassiana, biological control, Spodoptera frugiperda