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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Peanut and Small Grains Research Unit » Research » Publications at this Location » Publication #398973
Research Project: Management Strategies for Invasive Aphid Pests of Cereals

Location: Peanut and Small Grains Research Unit

Title: Aphid parasitism in winter wheat fields in a heterogeneous agricultural landscape

Author
item Elliott, Norman - Norm
item GILES, KRISTOPHER - Oklahoma State University
item BAUM, KRISTEN - Oklahoma State University
item ELZAY, SARAH - Oklahoma State University
item BACKOULOU, GEORGES - Langston University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2024
Publication Date: 4/18/2024
Citation: Elliott, N.C., Giles, K.L., Baum, K.A., Elzay, S.M., Backoulou, G.F. 2024. Aphid parasitism in winter wheat fields in a heterogeneous agricultural landscape. Journal of Economic Entomology. https://doi.org/10.1093/jee/toae073.
DOI: https://doi.org/10.1093/jee/toae073

Interpretive Summary: We found that the three parasitoid species L. testaceipes, D. rapae, and A. nigritus parasitized the cereal aphid R. padi on sentinel plants stationed in wheat fields in autumn and spring. The number of parasitoids per sentinel plant in wheat fields was positively correlated to the number of mummies per parasitoid inclusion cage indicating that the number of parasites per sentinel plant was a useful index of parasitism rate. The composition and configuration landscape elements in a 1.5 km radius circle surrounding wheat fields. During autumn abundance of L. testaceipes and A. nigritus was strongly and positively associated with coverage of summer crops and with Shannon’s landscape diversity index both of which are measures of landscape composition. Abundance of both species was negatively associated with contagion, a measure of landscape configuration. During spring abundance of D. rapae was strongly positively associated with patch density and density of summer crops. Parasitism by L. testaceipes and A. nigritus during spring was not associated with any landscape variable. Landscape variables that were significant contributors to parasitism of cereal aphids by L. testaceipes in this study were essentially the same variables found to be important in a study conducted about a decade earlier in central Oklahoma. The overall conclusion is that landscape structure has measurable and consistent effects on the ecology of aphid parasitoids of wheat central Oklahoma and indicate that knowledge of landscape structure can aid in predicting biological control services by cereal aphid parasitoids in winter wheat.

Technical Abstract: Several aphid species (Hemiptera: Aphididae) infest winter wheat fields in Oklahoma. We investigated spatial and temporal patterns of cereal aphid parasitoid species occurrence and abundance in wheat fields and their effect on cereal aphid population growth for three wheat growing seasons 2016-2017, 2017-2018, and 2018-2019. Parasitoid species occurrence and abundance were investigated using sentinel plants infested with bird cherry-oat aphids, Rhopalosiphum padi (L.) and effect of parasitoids on cereal aphid population growth was evaluated using exclusion cages infested with bird cherry-oat aphids. Composition and configuration landscape elements in a 1.5 km radius circle surrounding each of 7, 8, and 8 study wheat fields studied during each year was quantified. Lysiphlebus testaceipes (Cresson), Diaeretiella rapae (McIntosh), and Aphelinus nigritus (Howard) parasitized R. padi on sentinel plants. Lysiphlebus testaceipes was the most abundant species followed by A. nigritus, and D. rapae. Mean percent parasitism in predator exclusion cages was 31% in spring and 5% in autumn and aphid density was greater in complete exclusion than in predator exclusion cages. The number of parasitoids per sentinel plant in fields was positively correlated to the number of mummies per parasitoid inclusion cage. During autumn abundance of L. testaceipes and A. nigritus was strongly and positively associated with coverage of summer crops and with Shannon’s landscape diversity index. Abundance of both species was negatively associated with coverage of wheat and with contagion. For spring abundance of D. rapae was strongly positively associated with patch density and to a lesser extent with density of summer crops. Parasitism by L. testaceipes and A. nigritus during spring was not associated with any landscape variable.