"...However, I think a more successful approach for all concerned is in expanding the applications of our science."

Elliot Burden, President's Message, CAP Newsletter 17(1): 2-3, May, 1994

Introduction

Three species of mole crickets, so named for their ground burrowing activity (Scapteriscus abbreviatus, S. acletus and S. vicinus), were accidentally introduced to the southeastern United States about 80 years ago. Since that time these pest crickets have caused millions of dollars in damage to grasses, pastures, seedlings of vegetables, ornamentals and tobacco. Florida alone spends about US$30 million annually in control efforts to lessen the damage caused by the crickets (Sailer et al., 1984). Traditionally, insecticides have been applied to control the crickets; however, these methods are expensive, environmentally unsafe, and are not always effective.

In many of the southeastern United States, especially Florida, Georgia and Alabama, where the climate provides mild winters, golfing can be a year 'round activity. Of major concern to golf course superintendents is the proper grooming and care of their fairways and greens. Golfers pay for and have come to expect high playing standards and well-maintained courses. All this comes at a significant cost to the golf courses. The insect, herbaceous weed, and fungal infestations of golf courses are numerous and costly. A survey of 52 Long Island, NY, golf courses revealed that collectively they applied 21 different herbicides, 20 fungicides, and eight insecticides annually, totalling around 50,000 pounds of active chemical ingredients (Grossmann 1993). Joseph Okoniewski, Chief of New York's Department of Environmental Conservation, notes that "if you scraped a golf green and tested it, you'd have to cart it away to a hazardous waste facility" (Grossmann 1993).

Mole cricket damage to golf course greens and fairways, caused by the feeding, burrowing, and mound building of the three species of crickets, is extensive; and so far, control methods have resulted in only moderate success. In Florida and elsewhere in the southeastern U.S., three species of turf grass account for the majority of golf course plantings. Bermuda grass, Bahia grass, and St. Augustine grass are equally affected by the mole cricket burrowing and feeding on young roots of the grasses. A biological control method is clearly needed to safely, effectively and economically limit or eradicate mole cricket populations.

Control Methods

One method of biological control is the focus of research for Drs. J. Howard Frank, J. Patrick Parkman and colleagues at the Entomology and Nematology Department of the University of Florida, Gainesville, Florida. In 1988 Frank and his colleagues introduced a fly parasitoid (Ormia depleta) of Scapteriscus mole crickets into Florida. The fly, whose larval stages are host-specific parasitoid, is a tachinid native to South America. Gravid females are attracted to the songs of some species of Scapteriscus mole crickets and lay their larvae on the singing male crickets (only males sing) and any female mole crickets near him. Fly larvae burrow into and develop inside the adult mole crickets, killing the crickets in about seven days.

Since 1988 the fly has been released at several sites in southern and central Florida. By the end of 1991 the fly had been introduced to 32 sites, including 28 golf courses (Annual Report, Mole Cricket Research 92-93, 1993). Subsequent surveys indicated that the fly had spread, as predicted, to 29 counties in Florida and that in some counties the control of the pest mole crickets was remarkable (Frank et al. 1993). The control, however, was not consistent. In 1992 golf course superintendents reported varying degrees of success measured by visible damage to grass and fairways. Some courses noted a decrease in cricket damage, others reported an increase, while still others observed no change from the previous year. The fly was obviously not distributed equally across Florida in numbers which could effectively control the pest mole crickets.

It was suggested that the fly does extremely well at sites where adult flies have access to rich landscaping; many flowering trees and shrubs, some of which doubtless provide the nectar that adult flies need as an energy source. The evidence suggests that flies will do better where they have the availability of the nectar of flowering trees and shrubs; however, nobody knows which plants are important (Frank and Yount 1994).

The Canadian Museum of Nature

In October of 1993, I was contacted by Dr. Frank and Dr. Parkman with a proposal to join their team in an effort to identify the nectar feeding sources of Ormia depleta. The initial contact was made through a mutual friend, Dr. David Dilcher, Paleobotanist, Florida Museum of Natural History, with whom I worked while he was Professor of Botany/Paleobotany at Indiana University during 1969.

The nectar sources or feeding habits of adult Ormia depleta flies could be identified through careful analysis of associated pollen grains, either trapped in surface hairs or within the intestinal tract of the fly. Field observations of feeding/visitations of the fly to specific flowering plants is hampered by their low numbers and crepuscular and nocturnal activity. It was proposed that my assistant, Susan Jarzen, and I visit the University of Florida and observe a golf course currently suffering mole cricket damage, a fly trapping locality, and the fly/cricket rearing laboratories to better gain an appreciation for the research programme and to determine the level of involvement and approach by the Canadian Museum of Nature (CMN). It was agreed that my background knowledge of tropical and subtropical vegetation, coupled with the extensive, diverse Pollen/Spore Reference Collection held by the Museum, were conditions favorable towards an identification of the nectar feeding sources of Ormia depleta.

The five days spent in central Florida were hot and humid with some relief offered by the daily afternoon thunderstorms. Field observations were made and photographs taken of the cricket damage at the Ironwood Golf Course, a public facility in suburban Gainesville. (I noted at the time the lack of ornamentals planted about the golf course. Being a public course, little effort was taken to beautify the course with flowering plants of an "exotic" nature.) The superintendent, Bruce Cumming, allowed us free access to the greens and fairways, cautioning us that the "paying guests" had the right-of-way. The damage is, indeed, obvious and to the dismay of many a golfer, often causes disruption of an otherwise straight-line putt for par.

Later we visited a fly trapping station at the Green Acres Agronomy Farm operated by the University of Florida. The traps are operated via a timer to produce electronically the male songs of two mole cricket species. The operation at twilight excites and attracts female mole crickets and adult Ormia depleta flies, both of which are trapped for counting and study. A small sample of mature Ormia depleta flies collected in May 1994 from the Doral Golf Course in Miami, Florida, were provided to me for preliminary pollen examination. These samples were processed at the Palynology Laboratory, CMN, and provided a few forms of, as yet, unidentified tricolporate and stephanocolpate pollen.

Some pollen grains and/or fungal elements are associated with the flies. It is likely that their identification may be difficult, inasmuch as many, if not most, of the flowering plants associated with some golf courses are plantings of ornamental or exotic species supplied by nurseries specializing in plants adapted to central Florida climatic conditions. To understand this situation it was clear that a listing of plants commonly supplied to golf courses was needed and that eventually a collection of the pollen of those exotics not in the CMN pollen collection should be made. The San Felasco Greenhouses and Perennials and the San Felasco Nurseries, Inc., provided lists containing Latin and common names of 275 flowering plants which they supply as plantings to golf courses. It is interesting to note that the flora of peninsular Florida contains 3,500 native species, 900 exotic naturalized species, and over 25,000 non-naturalized exotics!! (pers. comm., J.H. Frank, 25 July 1994).

The future of the Canadian Museum of Nature's involvement in the mole cricket research programme will depend on several factors. The identification of pollen associated with the fly will be necessary to logically continue our involvement. The identifications will depend on availability of flies, the cooperation of staff at the University of Florida to provide SEM photos of pollen attached to the surface of flies, and adequate collections of the pollen of the native and exotic plants growing on, and adjacent to, golf courses from several localities in central and northern Florida. All this will take several years and adequate research funding. Unfortunately, funds earmarked by the Florida State legislature for mole cricket research were not provided after 1991, and grants from golf courses through the Florida Turfgrass Research Foundation expired in 1992.

Drs. Frank and Parkman have submitted grant requests to the U.S. Golfers Association and the Florida State Golfers Association, which includes funding for two years to partly cover the costs of palynological studies. If approved, the project would begin in the Spring of 1995. In the meantime, I will collect and analyze the available data and provide Drs. Frank and Parkman with the results of my preliminary examination of the small sample of flies I brought back to process for pollen. Whether biological control of mole crickets, and by extension other turf grass insect pests, is truly feasible and economically advantageous, will depend in part on the results of work performed at the University of Florida and at the Canadian Museum of Nature.

Palynologists are new to this business, and time and experience will teach us how to incorporate these sorts of societally relevant projects in our research programmes.

References

Annual Report, 15th, Mole Cricket Research 92-93. 1993. University of Florida, Gainesville, Institute of Food and Agricultural Sciences (IFAS), Entomology and Nematology Department, 199 pp. (unpublished).

Frank, Howard, Patrick Parkman, and Tom Walker, 1993. Red-eyed fly established throughout south, central Florida. Florida Turf Digest (Nov.-Dec.): 24-27.

Frank, Howard, and Robert Yount, 1994. Hey! The war isn't over yet! Florida Turf Digest (Jan.- Feb.):21-24.

Grossmann, John, 1993. How green are these fairways? Audubon (Sept-Oct.), pp. 90-96.

Sailer, R. I., J. A. Reinert, Drion Boucias, Philip Busey, R. L. Kepner, T. G. Forrest, W. G. Hudson, and T. J. Walker, 1984. Mole Crickets in Florida. University of Florida, Gainesville, Institute of Food and Agricultural Sciences (IFAS) Bulletin 846:1-54.

*Present address: Marie Selby Botanical Gardens, 811 South Palm Avenue, Sarasota, Florida 34236, USA
 

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  This article first appeared in CAP Newsletter 17(2):16-20, 1994.