Journal of Applied Entomology (2006) 130, 442-452

E. Quesada-Moraga, J.-A. Carrasco-Díaz and C. Santiago-Álvarez (2006)
Insecticidal and antifeedant activities of proteins secreted by entomopathogenic fungi against Spodoptera littoralis (Lep., Noctuidae)
Journal of Applied Entomology 130 (8), 442-452
Abstract: Entomopathogenic fungi are a poorly exploited source of insecticidal proteins, which may be used for the development of new natural insecticides and as alternative molecules for transgenic deployment. The crude soluble protein extracts in Adamek's liquid medium of 25 fungal isolates belonging to the fungal species Metarhizium anisopliae, Beauveria bassiana, Beauveria brongniartii and Scopulariopsis brevicaulis were screened by per os toxicity on Spodoptera littoralis larvae. Whilst extracts from two M. anisopliae and two B. bassiana isolates gave significant mortalities when applied either on alfalfa leaf discs or incorporated into artificial diet, the one from M. anisopliae 01/58-Su isolate was the only most toxic that showed promise for S. littoralis control. In leaf disc assays, this extract exhibited strong dose-related toxic and antifeedant activity against the larvae. At 10, 20 and 40 μg protein/insect, the extract gave 61.3%, 96.6% and 100.0% mortality, respectively, and average survival time of 5.7, 4.3 and 3.1 days respectively. Not only the antifeeding index was dose-related, but it significantly increased over time in a dose-related manner. Longer exposure times led to a dose-related significant increase in larval mortality. The exposure times for 50% mortality were 91.3 h and 62.1 h for 20 and 40 μg protein/insect respectively. The crude extract when exposed to higher temperature or protease treatment lost toxicity, indicating that toxicity was protein mediated. In addition, the liquid medium composition did not influence its insecticidal activity. The effects of the protein extract on midgut cells of second instar larvae of S. littoralis were investigated by using both light and electron microscopy. A progressive bleeding of the midgut epithelium into the gut lumen was observed along with lysis of the epithelium and deterioration of the microvilli.
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Link to article at publishers website
Database assignments for author(s): Enrique Quesada-Moraga, Candido Santiago-Alvarez

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera littoralis
Beauveria brongniartii (entomopathogen)
Beauveria bassiana (entomopathogen)	Spodoptera littoralis
Metarhizium anisopliae (entomopathogen)	Spodoptera littoralis
Scopulariopsis brevicaulis (entomopathogen)