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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #324908
Research Project: Management and Biology of Arthropod Pests and Arthropod-borne Plant Pathogens

Location: Emerging Pests and Pathogens Research

Title: Zoophthora radicans (Entomophthorales), fungal pathogen of Bagrada hilaris and Bactericera cockerelli (Hemiptera: Pentatomidae & Triozidae) in Mexico: Prevalence, bioassays, & environmental influences on conidial morphology

Author
item TORRES-ACOSTA, RI - Autonomous Agricultural University Antonio Narro
item Humber, Richard
item SANCHEZ-PENA, SR - Autonomous Agricultural University Antonio Narro

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2016
Publication Date: 7/30/2016
Citation: Torres-Acosta, R., Humber, R.A., Sanchez-Pena, S. 2016. Zoophthora radicans (Entomophthorales), fungal pathogen of Bagrada hilaris and Bactericera cockerelli (Hemiptera: Pentatomidae & Triozidae) in Mexico: Prevalence, bioassays, & environmental influences on conidial morphology. Journal of Invertebrate Pathology. doi:10.1016/j.jip.2016.07.017.

Interpretive Summary: This manuscript presents results about the recovery of what proved to be a single entomopathogenic fungus affecting two different hosts–Bagrada bugs and potato psyllids–in different families of sucking insects (Hemiptera) that are serious pests of cabbage-related (cole) crops in many parts of the world. The morphology of this fungus on the two hosts appeared to be so different as to suggest that two separate fungi might be operating. Detailed morphological studies on cultures from both hosts showed that there is only a single fungus, Zoophthora radicans, whose morphology shows significant host-based plasticity. The biology and cultural manipulation of Z. radicans is fairly well known, and this fungus should be regarded as a potentially useful biological control agent that could be applied against both Bagrada bugs and potato psyllids.

Technical Abstract: The Bagrada bug, Bagrada hilaris, and the potato/tomato psyllid, Bactericera cockerelli, are key pests of horticulture in western North America. In 2014 and 2015, adult and juvenile B. hilaris and B. cockerelli killed by fungi in the genus Zoophthora were detected at separate localities near Saltillo, northeastern Mexico. We report the field prevalence of Zoophthora on these insects. The spatial pattern of natural infection on potato psyllid nymphs and adults on greenhouse-cultivated pepper (Capsicum annuum L.) was analyzed; highest infection level of potato psyllid nymphs (32.3%) was on plant branch tips at 50 cm height. To clarify the specific identity of these Zoophthora populations, the morphologies and growth characteristics of both field collected specimens and pure in vitro cultures were compared. These observations indicate that, despite clear conidial morphological differences among the field collections from these two natural hosts, the infections on both hosts and localities can be attributed to the same fungal morphospecies (Zoophthora radicans), according to the morphometric data from in vitro cultures. Thus these observations underscore the importance of comprehensive analyses that include molecular and morphological data during identification of fungal samples. Laboratory dose-response bioassays were conducted with one Bagrada strain upon Bagrada bug nymphs. Exposure to conidial showers from agar cultures induced 30 to 90% mortality by Z. radicans on Bagrada bug nymphs. This is the first report of a natural enemy attacking Bagrada bugs in Mexico, and the first published report of entomophthoralean fungi naturally attacking Bagrada bugs and potato psyllids. Z. radicans should be investigated regarding natural and induced biological control of both hemipterans.