Full TGIF Record # 215086
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Web URL(s):http://archive.lib.msu.edu/tic/rpr/2000/72131,%20U%20Kentucky, Potter, wasps.PDF
    Last checked: 02/07/2013
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Publication Type:
i
Report
Material Type:Manuscript
Monographic Author(s):Potter, Daniel A.; Rogers, Michael E.
Author Affiliation:Department of Entomology, University of Kentucky, Lexington, KY
Monograph Title:Enhancing Biological Control of White Grubs by Native Parasitic Wasps on Golf Courses: 2000 Progress Report, 2000.
Publishing Information:Lexington, Kentucky: University of Kentucky
# of Pages:6
Collation:[6] pp.
Abstract/Contents:"Goals: 1) Investigate the biology, behavior, and importance of native and introduced species of Tiphia wasps, the predominant parasitoids attacking white grubs on golf courses. More specifically, we will: a) Determine which endemic Tiphia species most commonly parasitize white grubs on golf courses, and the range of grub species and instars that are attacked. b) Document the biology, seasonal life cycle, and incidence of native Tiphia, including periods of adult emergence and activity, oviposition behavior of wasps on grub victims, timing and duration of larval development, and incidence of parasitism as affected by grub population density and location on golf courses. c) Investigate oviposition behavior of Tiphia, particularly cues by which the wasps locate grubs and discriminate among grub species under the turf. 2) Determine the feasibility of enhancing Tiphia populations via habitat management, particularly through conservation or augmentation of wildflowers or other carbohydrate sources used by the adult wasps. We seek to: a) Identify wild or cultivated plants that are frequented by the adult wasps as carbohydrate (nectar or honeydew) sources; b) Test if higher parasitism occurs when such plants are incorporated into golf course landscapes. c) Determine if providing supplemental carbohydrate (sugar) sources for the adult wasps will increase parasitism rates of grubs. Tiphia wasps are the dominant group of parasitic insects that attack white grubs in the soil. During 2000, we determined that two species of Tiphia are common on golf courses in Kentucky. Adults of Tiphia vernalis, a species introduced for control of Japanese beetles, were active from May 4 to June 1. Tiphia pygidialis, a native species that attacks masked chafer grubs, were active from August 1 to Sepember 14. Yellow pan traps were effective for monitoring early-season activity of T. vernalis, whereas both species could be monitored with a 10% sugar water solution. Weekly sampling of the natural grub population showed that both Tiphia species parasitized primarily third instars. Parasitism of masked chafers averaged 15% at two golf courses, but was as high as 37% of some sites. Cues used by Tiphia to locate grubs below ground were examined by use of an "ant farm", positioned horizontally to allow observation of wasp behavior in the soil. Wasps were found to locate their victims by following species-specific scent trails left by the grub as it moves through the soil. They showed an even stronger response to frass from their host grubs. This is the first study to show how Tiphia wasps locate grubs underground. Ovipositional behavior of each wasp species was characterized. Both T. vernalis and T. pygidialis deliver a paralyzing sting and then manipulate the body of the grub in preparation for oviposition. Then, the female scrapes the grub to thin the cuticle where the egg with be laid. T. vernalis lays its egg on the underside of the grub, whereas T. pygilialis lays its egg on the back of the host grub. Eggs hatch in 3 to 5 days. Larval development is completed in about 21 days, after which a cocoon is spun. When offered Japanese beetle, masked chafer, or May beetle grubs, T. vernalis parasitized only Japanese beetles. Tiphia pygilialis were tested with the aforementioned grub species, plus two additional exotic species, European chafer and Oriental beetle. In general, only mased chafer grubs were attacked. In one case, however, T. pygidialis parasitized and completed larval development on a third-instar European chafer. The relationships between the developing larval Tiphia and its host also was examined. Shortly after being parasitized, grubs quit feeding on grass roots and move down into the soil to depths as much as 20 cm. We speculate that Tiphia wasps manipulate juvenile hormone levels in parasitized grubs, causing them to prematurely descend. Hemolymph was collected from normal and parasitized grubs to test this hypothesis. Our experiments show that once parasitized, grubs no longer contribute to turf damage. Persons monitoring for parasitized grubs should look deeper in the soil where such grubs will be found. Dilute sugar sprays were applied to small turf plots in an attempt to attract Tiphia wasps and increase parasitism of grubs. Although large numbers of wasps were attracted and observed feeding on the sprayed grass, no grubs were parasitized in sprayed plots. In adjacent, unsprayed turf, however, up to 37% of the grub population was parasitized. This indicates that sugar sprays applied near, but not firectly on, grub-infested turf may increase the rate of parasitism. Twenty species of slowering perennials were planted and monitored to determine if they attract Tiphia wasps. No wasps were found on these plantings. Since sugar water sprays did not attract any wasps when applied on surrounding turf, it is likely that no wasps were present at the study site. The wildflower test will be repeated elsewhere."
Language:English
References:0
See Also:See also related summary article, "Enhancing biological control of white grubs by native parasitic wasps on golf courses", 2000 Turfgrass and Environmenal Research Summary [USGA], 2000, p. 28, R=72131. R=72131
Note:Also appears as pp. 783-788 in the USGA Turfgrass Research Committee Reporting Binders for 2000
"Progress Report: 2000"
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http://archive.lib.msu.edu/tic/rpr/2000/72131,%20U%20Kentucky, Potter, wasps.PDF
    Last checked: 02/07/2013
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