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United States Department of Agriculture

Agricultural Research Service

Research Project: Biting and Stinging Pests: Ecology and Biologically-base Control

Location: Biological Control of Pests Research Unit

Title: Isaria poprawskii sp. nov. (Hypocreales: Cordycipitacae), a new entomopathogenic fungus from Texas affecting sweet potato whitefly

Authors
item Cabanillas, Humberto
item DE Leon, Jesus
item Humber, Richard
item Murray, Keith
item Jones, Walker

Submitted to: Mycoscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2012
Publication Date: September 9, 2012
Citation: Cabanillas, H. Enrique, deLeon, Jesse H., Humber, Richard A., Murray, K. Daniel, Jones, Waler A. 2013. Isaria poprawskii sp. nov. (Hypocreales: Cordycipitacae), a new entomopathogenic fungus from Texas affecting sweet potato whitefly. Mycoscience. 54: 158-169.

Interpretive Summary: The sweetpotato or cotton whitefly is one of the world’s worst insect pests, destroying a multitude of crops like cotton and vegetables around the world. The amount of pesticides used to control it is massive. Researchers have been trying to find effective natural enemies to reduce reliance on insecticides. Diseases of insects compose one class of natural enemies, but many are unreliable or otherwise not effective. A natural outbreak of an insect fungus in south Texas vegetables wiped out millions of whiteflies. Further examination showed that it was an undescribed species. Prior to it being used commercially, it has to be described in the scientific literature. This publication describes the new fungus after a famous researcher in microbiology. This fungal strain can now be distributed and applied in initial field experiments to determine how promising it can be to reduce whitefly populations in affected crops.

Technical Abstract: Isaria poprawskii is described as a new entomopathogenic species similar to Isaria javanica (=Paecilomyces javanicus). It was discovered ont he sweet potato whitefly, Bemisia tabaci biotype B in the Lower Rio Grande Valley of Texas (LRGV), USA. Morphological and DNA examinations indicated the distinctness of I. poprawskii from the ex-type isolate of I. javanica. I. poprawskii produced light yellow young colonies to darker yellow with a grayish-violet center to a taupe or a brownish-gray mature conidial mass; conidia hyaline, one-celled, 3.9 (2.9-4.6) um long x 1.6 (1.4-2.1) um wide; colored synnemata, but I. javanica ex-type produced white colony, hyaline conidia and no synnemata. A phylogenetic position of I. poprawskii was inferred by a nucleotide sequence analysis of B-tubulin along with standard B-tubulin sequences from GenBank. Fifteen unsequenced isolates, including eight fromt he LRGV, were investigated. The analysis confirmed that I. poprawskii could be recovered from LRGV fields, and that both I javanica and I. poprawskii are present in the LRGV in symtatry. I. poprawskii was shown to be closely related to I. javanica; however, it formed its own unique clade, thus cconfirming its status as a new fungal species.

Last Modified: 7/31/2014
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