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Pathogen‐mediated modulation of host metabolism and trophic interactions in Spodoptera littoralis larvae
Author(s) -
Shaurub ElSayed H.,
Reyad Naglaa F.,
Mohamed Amr A.
Publication year - 2020
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1111/eea.12998
Subject(s) - biology , beauveria bassiana , spodoptera littoralis , pyralidae , instar , trehalase , lepidoptera genitalia , microbiology and biotechnology , amylase , botany , noctuidae , biological pest control , larva , biochemistry , trehalose , enzyme
The success and sustainability of entomopathogens in insect control depend on their stress potential and ability to modulate certain physiological aspects of their insect hosts. In the present study, newly moulted fourth instars of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) were incubated for 24 h with the median lethal dose (LD 50 ) of Steinernema riobrave , Heterorhabditis bacteriophora , or Beauveria bassiana to determine their effects on certain metabolic activities and nutritional physiology compared to those of uninfected (control) larvae. Infection decreased total protein, lipid, and carbohydrate contents. Carbohydrase activity was found to be pathogen and enzyme dependent, with S. riobrave and H. bacteriophora infection increasing amylase, invertase, and trehalase activities. Beauveria bassiana infection decreased amylase and invertase activities but increased that of trehalase. Infection with the three pathogens also enhanced phosphatase activity. All pathogens reduced transaminase activity. Changes in the nutritional indices varied not only with the variation in the candidate entomopathogen and surviving instar but also with the variation in the age of the same instar, with a profound change in late last instars (3‐day‐old sixth instars). The link between the metabolic activities and nutritional indices was discussed. Overall, the entomopathogen‐host interaction appears to be primarily nutritional. The pleiotropic effects of the median lethal infections on the insect pest might eventually help in the biological control potential of the entomopathogens tested.