Elicitors of host plant defenses partially suppress pear psylla (Cacopsylla pyricola, Hemiptera: Psyllidae) populations under field conditions

Authors: Cooper, William - Rodney; Horton, David

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2017
Publication Date: 3/29/2017
Publication URL: https://handle.nal.usda.gov/10113/6472176
Citation: Cooper, W.R., Horton, D.R. 2017. Elicitors of host plant defenses partially suppress pear psylla (Cacopsylla pyricola, Hemiptera: Psyllidae) populations under field conditions. Journal of Insect Science. 17(2):49.

Interpretive Summary: Pear psylla is the key insect pest of pear in the United States. This insect is primarily controlled using insecticides, and ongoing research seeks to discover new ways to manage this pest. Defense elicitors are foliar treatments which activate plant defenses leading to broad-spectrum immunity to numerous pests. Scientists at the USDA-ARS laboratory in Wapato, Washington tested the effects of three elicitors of plant defenses against pear psylla under field conditions. They found that the commercial elicitors, Actigard, Employ, and ODC each reduce numbers of the damaging stage of pear psylla, but not enough to warrant the use of these products specifically for psyllid management. However these products are often used to control fire blight in pear orchards, and knowledge that these products also reduce pear psylla may be useful for integrated pest management.

Technical Abstract: Defense elicitors are products that activate acquired defense responses in plants, thus rendering the plants less susceptible to attack by a broad range of pests. We previously demonstrated under laboratory conditions that foliar applications of the defense elicitors Actigard (acibenzolar-S-methyl), Employ (harpin protein), or ODC (chitosan) on pear (Pyrus communis L.) each increase mortality of Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) nymphs, and alter the settling and oviposition behavior of the adults. In a three year study, we monitored C. pyricola populations on orchard-grown trees treated with water (untreated control), Actigard, Employ, or ODC. Fewer nymphs were observed on trees treated with elicitors compared with untreated trees in both 2014 and 2016. A similar but non-significant pattern was observed in 2015 when nearly 30% fewer nymphs were observed on trees treated with elicitors versus untreated controls. Observed reductions in psyllid numbers by defense elicitors were modest, and do not warrant the use of these products specifically for control of C. pyricola. However, these products are often used for management of fire blight, and knowledge that elicitors may also reduce C. pyricola populations may be useful for system-wide integrated pest management approaches.