Sweetpotato weevil, Cylas formicarius (Fab.)(Coleoptera: Brentidae) avoids its host plant when a virulent Metarhizium anisopliae isolate is present

Dotaona, Ronnie and Wilson, Bree A. L. and Ash, Gavin J. and Holloway, Joanne and Stevens, Mark M. (2017) Sweetpotato weevil, Cylas formicarius (Fab.)(Coleoptera: Brentidae) avoids its host plant when a virulent Metarhizium anisopliae isolate is present. Journal of Invertebrate Pathology, 148. pp. 67-72. ISSN 0022-2011


Metarhizium anisopliae has a wide range of coleopteran hosts, including weevils. Some susceptible insects are known to modify their behavior to prevent infection, typically detecting virulent strains by olfaction, and avoiding physical contact with sources of infection. Laboratory olfactometer assays were conducted on the sweetpotato weevil Cylas formicarius to test the hypothesis that insects would avoid a more virulent strain of M. anisopliae when presented with a strain of low virulence or an untreated control. When adult weevils were allowed to choose between paired test arenas containing sweetpotato roots and M. anisopliae isolates on agar cores, weevils avoided arenas with the highly virulent isolate QS155, showing a preference for either roots with uninoculated agar cores or cores with the low virulence isolate QS002-3. When roots or whole sweetpotato plants were inoculated with M. anisopliae, the preferences of weevils remained broadly similar; weevils were repelled by the highly virulent isolate QS155 when tested against either QS002-3 or uninoculated roots and plants, however weevils were not repelled by the low virulence isolate QS002-3 tested against uninoculated controls. When single-sex groups of weevils were tested separately in the olfactometer using uninoculated whole plants and plants treated with isolate QS155, males and females responded similarly and statistically identical preferences were found for the untreated plants. When weevils were released singly at different times of the day the response time for males was significantly shorter in the afternoon compared to the morning. Males were always significantly faster to respond to olfactory stimuli than females. Understanding factors that may lead to avoidance of virulent M. anisopliae strains by C. formicarius will be an essential part of developing an ‘attract-and-infect’ strategy for the management of C. formicarius.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version cannot be displayed due to copyright restrictions.
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Crop Health
Date Deposited: 09 Apr 2019 05:36
Last Modified: 18 Apr 2019 02:05
Uncontrolled Keywords: Cylas formicarius; Metarhizium anisopliae; virulence; sweetpotato; olfaction; behavior; avoidance
Fields of Research : 07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070308 Crop and Pasture Protection (Pests, Diseases and Weeds)
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences
Identification Number or DOI: 10.1016/j.jip.2017.05.010
URI: http://eprints.usq.edu.au/id/eprint/35644

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