Use of Parasitoids and Passive Traps as Alternative Methods of Fly Control on Dairy Farms in Arkansas

View the project final report

• 2003 annual report
• 2005 annual report

Commodities

• Animal Products: dairy

Practices

• Animal Production: parasite control, animal protection and health, manure management, preventive practices
• Farm Business Management: whole farm planning
• Pest Management: biological control, chemical control, economic threshold, physical control, prevention, sanitation
• Production Systems: agroecosystems, holistic management

The project was to investigate the use of parasitoids and passive traps as alternative methods of fly control on dairy farms in Washington County, Arkansas with the objective of lowering chemical resistance of flies and decreasing the likelihood of milk contamination with insecticides. The project also made more dairy producers aware of the importance of integrated pest management (IPM), sanitation, and alternative chemicals as methods to control flies on the dairy.
Eleven dairies in 2003 and 10 in 2004 participated in the project which was conducted for 20 weeks throughout the summer. Six dairies received weekly shipments of parasites while five dairies served as controls in 2003; five received parasites in 2004 and five were controls in 2004. An agricultural technician distributed the parasitoids and counted horn flies, stable flies and face flies on the cows. To monitor house flies, 3” by 5” index cards were replaced weekly and fly specks were counted to compare fly populations. Fly strips also were used on two dairies that received wasps and on two control dairies to capture flies. This provided a comparison on the number and different types of flies at the facilities. Premises also were scored for cleanliness to relate it to fly counts. In 2003, one dairy used a walk-through fly trap for horn fly control; one was also on a dairy in central Arkansas and one on a beef farm. In 2004, three fly traps were on dairies in Washington County. Two 4-H families also participated in the trial; one livestock project received parasites and the other served as a control.
When compared to control dairies, dairies receiving parasites had only half the number of house flies on fly strips which were allowed to hang for 1 week at the farms. Stable flies also were reduced on farms utilizing parasites. Compared to the 4-H project barn serving as a control, the 4-H project barn receiving parasites had markedly fewer fly specks on index cards all summer long. On one beef farm, the horn flies were reduced by 43% with fly traps as compared to control cows. The fly traps appeared to work well in reducing horn fly counts but were neither utilized to maximum potential nor accepted well by all dairy producers. They need to be placed where they minimize obstruction to both human and cow traffic but still require twice daily cow flow. Parasites are more effective in a clean environment and were less effective in controlling flies on farms with lower cleanliness scores.
Although these results are favorable for the use of parasitoids to control house and stable flies, additional work specifically measuring the degree of parasitism by parasitoids is needed before we routinely recommend their use on dairy farms. Use of fly traps has potential to reduce horn fly numbers but needs to be accepted by the producer before they are recommended for use.

Introduction

Horn flies, face flies, stable flies and house flies are significant fly pests of dairies, both cattle and premises. Fly populations on dairy cows during the warm months of the year can irritate cows and spread disease from one animal to another. The energy taken to resist or fight the flies takes away nutrients that could be used for milk production and can add to the heat stress of the summer. Estimates of loss of milk production and spread of disease vary, but research has shown that heavy infestations of stable flies can reduce milk production by 15-30% and horn flies can reduce milk by 10-20%.

Fly populations also can develop resistance to chemicals available to control flies and the resistance of flies to insecticides has become a significant problem on dairies in Arkansas. Arkansas Dairy Cooperative Association (ADCA) presently has a SARE Producer Grant involving the use of parasitoids to control flies on dairy farms in central Arkansas. The project has been very successful in controlling flies but has not had widespread acceptance among dairy producers other than those producers who are directly involved with the project. Only two producers other than those on the project have used parasitoids. Moreover, in the first year of the trial, cooperating dairy farms that utilized parasitoids had three of seven producers use extensive insecticides as well. Although the producers using more insecticides did not significantly differ in fly control than the producers that used very limited insecticides, the data showed us that producers had little confidence in the parasitoids. In 2002, the use of insecticides by producers using parasitoids were decreased greatly but producers still are reluctant to use parasitoids for fly control, other than the producers that are cooperating on our trial.

Our goal was to develop a fly control program for dairy farms by 1) incorporating additional integrated pest management (IPM) practices on the dairies, 2) expanding our past trials to the northwest corner of the state to expose more producers to IPM and parasitoids, and 3) adding walk-through fly traps to the methods of horn fly control. The passive fly trapping method has been shown to provide about 70% control of horn flies. We also put additional emphasis on proper manure management as the project with ADCA indicated that fly populations were related to the amount of manure on the farms. With passive fly traps, producers had (1) a method of non-chemical control for horn flies which should not aggravate resistance to insecticides and (2) greater confidence in IPM strategies to control horn flies without the benefit of excessive insecticide use. Horn flies, face flies, stable flies and house flies are significant fly pests of dairies, both cattle and premises. Research has shown that heavy infestations of stable flies can reduce milk production by 15-30% and horn flies can reduce milk by 10-20%. Fly populations also can develop resistance to chemicals available to control flies and the resistance of flies to insecticides has become a significant problem on dairies in Arkansas.