Submitted to: Crop Protection Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/6/2011
Publication Date: 10/1/2011
Citation: Xiao, Y., Osborne, L.S., Chen, J., McKenzie, C.L., Houben, K., Irizarry, F. 2011. Evaluation of corn plants as potential banker plant for supporting predatory gall midge, Feltiella acarisuga (Diptera: Cecidomyiidae) against Tetranychus urticae (Acari: Tetranychidae) in greenhouse vegetable production. Crop Protection 30(12):1635-1642. Available: doi:10.1016/j.cropro.2011.09.004. Interpretive Summary: The predatory gall midge is among the most effective biological control agents against twopotted spider mites. Compared to predatory mites, the gall midge consumes more spider mites (any stage) on many different crops. However, difficulty in sustaining and maintaining this predator in greenhouses or fields has lead to failure in suppressing pest populations below economic threshold levels when used as a biological control agent. The development of a banker plant system for maintaining high densities of this predator is a key step for sustainable greenhouse bean production. We identified corn as a potential non-crop candidate banker plant for rearing alternative prey and natural dispersal of the predatory gall midge. Corn plants are a good host plant for Banks grass mite which is an excellent alternative prey for for the gall midge. The gall midge proved to be an excellent predator and was able to disperse by flight at least 7.0 m away from the infested banker plant to the target crop and pest. These studies suggest that corn plants (banker plants), Banks grass mite (alternative prey), and the predatory midge constitute an excellent potential banker plant system. This system should provide a new approach to control two-spotted spider mite for greenhouse vegetable growers.
Technical Abstract: The twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important and highly polyphagous pests of vegetables and other crops worldwide. In this study, several experiments were conducted under laboratory and greenhouse conditions to evaluate whether corn plant (Zea mays L.) is a potential non-crop banker plant for the predatory gall midge, Feltiella acarisuga (Diptera: Cecidomyiidae). Multi-choice and no-choice experiments were conducted to determine the host plant specificity of an alternative prey, Oligonychus pratensis (Acari: Tetranychidae) to green bean and tomato plants. Results revealed that the corn plants were a non-target crop banker plant for supporting the non-target pest prey, O. pratensis for feeding and reproduction, whose larvae showed strong host specificity to corn plants in both multi-choice and no-choice tests. Furthermore, the dispersal ability of F. acarisuga from corn banker plants to green bean plants infested by T. urticae was investigated in greenhouses, and predation by F. acarisuga to T. urticae infested on green bean plants was examined in laboratory and greenhouses. F. acarisuga was able to disperse by flight at least 7.0 m away from corn banker plants and the number of F. acarisuga found on green bean after 5-14 d dispersal ranged from 8-176 larvae per leaf. F. acarisuga proved to be an excellent predator with percent predation between 43.7- 67.9 percent on T. urticae compared to 59.2 - 90.3 percent on O. pratensis under laboratory conditions and no significant differences in the percent predation were recorded after dispersal. In closed caged greenhouse studies, T. urticae was suppressed by 81.2 percent compared to the control treatment. These studies suggest that corn plants (banker plants), O. pratensis (alternative prey), and F. acarisuga (predatory midge) constitute an excellent potential banker plant system. This system should provide a new approach to control T. urticae for greenhouse vegetable growers.