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Title: Relative susceptibility of pecan germplasm to blackmargined aphid

item SKRIVANEK, SARAH - Texas A&M University
item Grauke, Larry
item Martin, Daniel - Dan
item Thompson, Tommy
item HARRIS, MARVIN - Texas A&M University

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2013
Publication Date: 3/1/2013
Citation: Skrivanek, S., Grauke, L.J., Martin, D.E., Thompson, T.E., Harris, M. 2013. Relative susceptibility of pecan germplasm to blackmargined aphid. Southwestern Entomologist. 38(1):33-40.

Interpretive Summary: Problem: The blackmargined aphid damages pecan trees by sucking sugars from their leaves, which drips to the ground as honeydew, wasting the food needed to build leaves, nuts and shoots. Pecan growers often spray their orchards to kill the aphids, which costs money for the chemicals, time for the applications, may kill helpful insects, and threatens the health of workers making the sprays and safety of foods. We need to increase resistance to aphids in pecan trees in order to develop healthier trees, spend less money, and protect the environment. We showed that water sensitive cards detect honeydew related to aphid population levels and provide an efficient way to rate relative aphid susceptibility. These methods will help us identify trees with useful aphid resistance and will lead to the development of better cultivars.

Technical Abstract: The blackmargined aphid, Monellia caryella (Fitch), is an important phytophage in the pecan, Carya illinoinensis (Wangenh.) K. Koch, agroecosystem where it often is treated with insecticide. Pecan cultivars released by the USDA Pecan Breeding Program vary in susceptibility and risk of damage from the blackmargined aphid. We evaluated a new technique that measures honeydew deposition and found that relative differences in susceptibility of a segregating pecan population were identifiable during the course of an outbreak of blackmargined aphids. This provided an efficient method for the simultaneous evaluation segregating pecan trees. Use of this new tool will also aid studies of inheritance, horticultural compatibility, and in determining the relative permanence of this character in pecan improvement.