1) The use of parasitoid wasps to control house flies and stable flies in dairy operations in Arkansas, North Carolina and Mississippi.
The house fly and stable fly are major pests associated with dairy facilities in the United States. These flies can occur in large numbers around livestock facilities where they breed in accumulations of organic waste and manure. They are of major nuisance in urban environments. Livestock producers expend considerable effort to control flies and use a combination of three control strategies: cultural control, chemical and biological control.
Cultural control is an essential component of management strategies and involves removing spilled feed and manure frequently to eliminate potential development sites for fly larvae. Cultural control alone is often only partially undertaken and producers rely on applications of insecticides to reduce populations of flies. Insecticides are becoming more costly, more regulated and the development of insecticide resistance in flies is becoming an important problem. In addition, with the increased consumption of organic products such as milk, meat and eggs, producers are exploring methods of biological control (the use of natural enemies to control flies).
Several species of pteromalid wasps are commercially produced and have been widely used in livestock facilities as biological control agents of house flies. They parasitize a house fly pupa by laying an egg in each house fly pupa. Instead of a house fly emerging, a parasitoid wasp emerges. By increasing mortality of fly pupae, released and naturally occurring parasitoids can represent an effective compliment to cultural practices.
Although many parasitoid surveys and release programs have been conducted in the United States, the majority of those surveys have been in the northeast. No studies have been done on Southeastern dairies. Therefore, we are:
A) Determining the species, seasonal occurrence and numbers of parasitoids that are present in Arkansas, Mississippi and North Carolina dairies.
B) Evaluating parasitoid dispersal and level of house fly parasitism after releasing wasps in dairy agroecosystems.
C) Transferring this research to dairy producers so that these producers can use these parasitoid wasps into their fly management programs.
2) Oviposition behavior of Muscidifurax zaraptor, a parasitoid of house flies and stable flies.
The biology of these wasps has been extensively studied, including the adjustment of progeny sex ratios by females through controlled fertilization. Females lay more female eggs in large house fly pupae, and more male progeny in small house fly pupae. Larger hosts may be higher quality than smaller ones. Host size has a more positive effect on the fitness of females than males because females are larger than males and require more resources for development.
Recently, a new pathogen Nosema sp. was discovered in Muscidifurax colonies. This pathogen reduces fecundity and longevity, and distorts body size. The primary objective of this study is to determine the impact of a Nosema infection on sex ratio, using Muscidifurax zaraptor and Musca domestica (house fly) as the model species. Understanding how host size influences sex ratio has practical applications for the mass production and quality control of wasps used as biological control agents. This research is of great importance to the wasp producing industry.
3) The impact of poultry litter fertilizers on ground-dwelling arthropods.
Arkansas is one of the principal agricultural states in the United States and was ranked second in broiler chicken production (1.170 million birds) in 2003 and 2004. Most poultry litter from these commercial poultry operations contains arsenic and other heavy metals from the use of roxarsone, an arsenic feed additive that is given to chickens to increase growth. Because of the high nutrient content, poultry litter is reused as fertilizer for neighboring agricultural fields. Previous research indicates that the composting of poultry litter may release roxarsone and its byproducts into the environment, which may impact soils, plants, insects, and water resources from the accumulation of arsenic over time. We are investigating the mobility and concentration of roxarsone and its biproducts in soils, plants and insects. A series of experiments are being performed on a Bermuda grass and common insects (ground beetles, litter beetles, ants and spiders) to establish whether or not crops and insects/arthropods are affected by the accumulation of arsenic in the soils. The buildup of these toxic metals in the environment may adversely affect terrestrial biota and flora, directly impacting human health through bioaccumulation in the food chain. If insects and crops can bioaccumulate these arsenic species, then humans may ingest these arsenic compounds via the consumption of plant crops directly and/or through the consumption of animals that either feed on these crops or insects.
4) The biodiversity of dung beetles in Arkansas.
To reduce horn fly numbers, farmers use endectocides. Endectocides are a class of drugs used to control parasitic arthropods of livestock. Endectocides are administered though a variety of methods (oral, injection, pour-on, or bolus) and are excreted primarily unchanged in the feces of the treated animal. These products mimic insect growth hormones, keeping the horn fly larva in the immature stage, ensuring it will never develop into an adult. Unfortunately, these endectocides are also harmful to dung beetles.
The objectives of this study is to determine the effects of endectocides on dung beetles in northeast Arkansas. By conducting a survey of the dung beetle populations in this area with and without treated dung, we will determine the effects endectocides have on these beneficial insects.
5. Monitoring stored grain insects in rice storage facilities in northeast Arkansas.
In collaboration with Texas A & M University, University of Arkansas, United States Department of Agriculture – Grain Marketing, Manhattan, Kansas, and Louisiana State University, Dr. McKay's lab will begin monitoring insects of stored rice in northeast Arkansas. Insect infestation levels and rice quality will be determined, along with the seasonal patterns of stored grain insects in and around rice mills.