Field validation of a system for autodissemination of an entomopathogenic fungus, Isaria fumosorosea, to control the Asian citrus psyllid on residential citrus

Authors: CHOW, ANDREW - TEXAS A&M UNIVERSITY; Patt, Joseph - Joe; SETAMOU, MAMOUDOU - TEXAS A&M UNIVERSITY

Submitted to: International Research Conference on Huanglongbing
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2016
Publication Date: 1/1/2017
Citation: Chow, A., Patt, J.M., Setamou, M. 2017. Field validation of a system for autodissemination of an entomopathogenic fungus, Isaria fumosorosea, to control the Asian citrus psyllid on residential citrus. International Research Conference on Huanglongbing. https://escholarship.org/uc/item/2cr0f2kc.

Interpretive Summary: The citrus industries of California and Texas share a pressing problem with the Asian citrus psyllid and huanglongbing spreading in residential citrus near commercial groves. Insecticidal treatment of residential trees for the psyllid is problematic and not cost effective; therefore, control of this insect vector in urban areas needs to rely heavily on natural enemies such as fungi that attack the psyllid. A fungi named Isaria fumosorosea (‘Ifr’ for short) readily attacks this psyllid in nature and available commercially by the tradename ‘PFR-97’. “Autodissemination” is the dispersal of a fungus by an insect to its kin and PFR 97 is ideal for autodissemination because it is tolerant to drying out and the fungal spores in PFR 97 germinate quickly once they are present on the psyllid. Autodisseminators can be deployed in residential citrus trees to attract and infect psyllids with PFR-97 for the purpose of inducing epidemics that will decimate psyllid populations on these trees. During the fall and winter of 2015, we deployed autodisseminators treated with PFR-97 formulation on residential citrus trees in the Rio Grande Valley of Texas. For one study, we recovered autodisseminators after 1, 7, 14 or 21 days and tested their PFR-97 formulation for effectiveness against adult psyllids. For a second study, we monitored psyllid populations for 12 weeks on trees without autodisseminators (controls) and trees with 1, 2, or 4 autodisseminators which were replaced every two weeks. We found that PFR-97 formulation recovered after 1 to 14 days of weathering could still infect adult psyllids. The average reduction of psyllid populations on trees with autodisseminators ranged from 30 to 79 %. Based on our results, we determined that a single autodisseminator per tree and replacement every two weeks was optimal for psyllid control. Our findings show that autodissemination of Ifr could be a key component of a sustainable management system for Diaphorina citri in residential landscapes.

Technical Abstract: The citrus industries of California and Texas share a pressing problem with the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) and huanglongbing (HLB) spreading in residential citrus near commercial groves. Insecticidal treatment of residential trees for the psyllid is problematic and not cost effective; therefore, control of this insect vector in urban areas needs to rely heavily on natural enemies such as entomopathogens. The entomopathogenic fungi Isaria fumosorosea (Ifr) Wize (Hypocreales: Cordycipitaceae) is highly pathogenic towards Diaphorina citri and available as a commercial blastospore formulation (PFR-97) for use in autodissemination management strategies. “Autodissemination” is the dispersal of an entomopathogen by an insect to conspecifics and Ifr blastospores are ideal for autodissemination because they are desiccation tolerant and germinate quickly on suitable hosts. Autodisseminators can be deployed in residential citrus trees to attract and infect D. citri adults with PFR-97 blastospores for the purpose of inducing epizootics that will decimate psyllid populations on these trees. During the fall and winter of 2015, we deployed autodisseminators treated with PFR-97 formulation on residential citrus trees in the Rio Grande Valley of Texas. For one study, we recovered autodisseminators after 1, 7, 14 or 21 days and tested their PFR-97 formulation for infectivity against Diaphorina citri adults. For a second study, we monitored Diaphorina citri populations for 12 weeks on trees without autodisseminators (controls) and trees with 1, 2, or 4 autodisseminators replaced every two weeks. We found that PFR-97 formulation recovered after 1 to 14 days of weathering could still infect adult psyllids. Mean reduction of psyllid populations on trees with autodisseminators ranged from 30 to 79 %. Based on our results, we determined that a single autodisseminator per tree and replacement every two weeks was optimal for psyllid control. Our findings show that autodissemination of Ifr could be a key component of a sustainable management system for Diaphorina citri in residential landscapes.