Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2011
Publication Date: 8/25/2011
Citation: Avery, P.B., Wekesa, V.W., Hunter, W.B., Hall, D.G., McKenzie, C.L., Osborne, L.S., Powell, C.A., Rogers, M.E. 2011. Effects of the fungus Isaria fumosorosea (Hypocreales: Cordycipitaceae) on reduced feeding and mortality of the Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae). Biocontrol Science and Technology. 21(9):1065-1078. Available: http://dx.doi.org/10.1080/09583157.2011.596927. Interpretive Summary: An insect-infecting fungal pathogen increases mortality of Asian citrus psyllids. The entomopathogenic fungi sold as the product PFR 97 (Trademark) was shown to be effective at killing and reducing feeding of the Asian citrus psyllid. The psyllid spreads a devastating bacterial disease to citrus trees and is threatening citrus production throughout the United States. The effect of two PFR 97 formulations (blastospores and conidia) on feeding, honeydew deposits, and survival of adult psyllids was assessed. Psyllids infected by either formulation had reduced feeding, with mortality reaching 100 percent within 7 days. Blastospores caused a significantly higher mortality than conidia within the first 3 days. The use of this fungus, which is specific to insects, is advantageous because, apart from reducing feeding by psyllids, those that are infected by the fungus may not be able to spread the disease, while at the same time, infected-psyllids may help spread fungus throughout the citrus groves, thus killing even more psyllids.
Technical Abstract: The entomopathogenic fungi, Isaria fumosorosea Wize, reduced feeding of psyllids upon infection. Psyllids transmit the plant-infecting bacterium which causes Huanglongbing, in citrus trees, thus disruption of psyllid feeding may provide an added measure of control to reduce disease spread. The effects of two formulations of Isaria fumosorosea Wize (blastospores and conidia) on feeding, honeydew droplets, and mortality of adult Diaphorina citri Kuwayama (Hemiptera: Psyllidae) was assessed in bioassay arenas. One and two days after release, psyllids in the blastospore treatments had significantly fewer honeydew droplets than the other two treatments and psyllid mortality increased at two days post-exposure. Psyllids infected by either formulation had reduced feeding as indicated by significantly fewer honeydew droplets produced [8 and 9 times less after 5 and 7 days, respectively] along with mortality reaching 100 percent in fungal treatments compared to 0 percent in the controls 7 days post-treatment. The cumulative mean number (plus SEM) of honeydew droplets 7 days post-treatment was significantly higher in the control (34.5 approximately 4.0)versus all other treatments. Droplets produced were not significantly different between the blastospore (5.97 approximately 1.6) and conidial (9.20 approximately 1.5) treatments. This study provides further evidence that I. fumosorosea (Pfr 97) can be highly effective against psyllids causing up to 100 percent mortality 7 days post-treatment. The use of this fungus can be advantageous because, it can induce reduced feeding by psyllids, reduce the ability of infected psyllids to spread disease, and be further propagated and spread by infected psyllids throughout citrus groves. The potential of auto dissemination of Pfr 97 by psyllids in the field is still being investigated.