Final Report for OS03-016
Project Information
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.
Research
Parasitoids were released weekly on the parasitoid dairy farms, plus a fly trap was utilized to control horn flies on one dairy farm in 2003 and on three of the parasitoid dairy farms in 2004. (An additional dairy farm in central Arkansas and a beef farm also used fly traps.) Monitoring techniques were spot cards in the milking center area to identify numbers of house flies plus fly counts on the cows were utilized to verify the effectiveness of parasitoids treatment on a weekly basis. The control farms will also be monitored in a similar manner. The total cost of integrated pest management system, the cost of parasitoids, the passive fly traps, and other insecticides were monitored for comparison of costs at the end of the project.
A part-time technician was hired to conduct weekly farm visits to cooperating herds using the parasitoids, parasitoids with traps, and traditional fly control methods of insecticides. The technician monitored fly populations in and around the milking center and fly populations on cows.
The parasitoids (Muscidifurax raptorellus, Muscidifurax zaraptor, and Spalangia cameroni) were distributed based on 200/cow/week (or 1000/calf/week if applicable) and were purchased from Beneficial Insectary Company, Redding, CA. The passive fly traps on three of the six parasitoid dairies were a wood structure that cows walked through as they went to the milking parlor. Flies will be brushed off the sides and backs of cows by canvas strips and attracted by natural light to a passive screened trapping element where they are captured. The amount of flies in the trap were monitored (probably underestimated because some portion of the dead flies will be consumed by scavenger insects) and flies were discarded as needed. Most of the flies were horn flies, but we estimated the percentage of horn, face, house, and stable flies as they were discarded.
House flies were monitored by spot cards placed in the holding pen, milking parlor, milk house, and dry stack of each farm included in the project. Horn flies were monitored by conducting fly counts on the shoulders, backs, and sides of at least ten milk cows per week on each farm. Stable flies were monitored by counting flies on all four legs of at least ten dairy cows on each farm. Face flies were monitored by counting flies on faces of at least ten milk cows on each farm. The part-time technician provided weekly feedback to dairy producers concerning levels of fly infestation so that the producers knew when they should treat with insecticides. Proper manure management was emphasized for all producers
Costs of the various fly control methods were compared to demonstrate the economic effectiveness of the parasitoids as well as the costs of other fly control methods.
The results were presented at county and area dairy production meetings throughout the state and in monthly dairy publications (as well as yearly publications later).
The part-time technician provided weekly feedback to dairy producers concerning levels of fly infestation so that the producers knew when they should treat with insecticides. Tentative estimates indicate that producers utilizing parasitoids spent more per cow on fly control costs than producers serving as a control but also had enhanced fly control. Dairies receiving parasitoids had only half the number of house flies on fly strips compared to control dairies. Compared to the 4-H project barn serving as a control, the 4-H project barn receiving parasites had about 50% fewer fly specks on index cards all summer long.
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. 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.
Educational & Outreach Activities
Participation Summary:
We had meetings with parasites and the fly trap as topics in the three primary locations for dairy farms in Arkansas: central, River Valley, and northwest Arkansas. Additional articles were published twice in the Dairy Digest, a statewide newsletter for the dairy industry. A power point presentation showing how to utilize fly parasites was developed for use by county agents. Perhaps the most significant outreach is the use of IPM techniques by producers which encourages them to treat with insecticides only when needed.
Project Outcomes
Dairy producers in Washington County now are more knowledgeable of parasitoids and are more interested in the possibility of non-chemical fly control. They still need to have enough confidence in the parasitoids to treat only when fly populations reach a specified level so as to lower overall costs of fly control, the basic principle of IPM. The parasitoids appeared to yield lower numbers of house flies and the possibility of lowering stable fly numbers. One dairy in Washington County used a walk-through passive fly trap for horn fly control in 2003; one was also on a dairy in central Arkansas and one on a beef farm. In 2004, we will have three on dairies in Washington County with fly traps, with the goal of having less treatment of cows with insecticides, thus reducing the chances of milk contamination and insecticide resistance.
Economic Analysis
Tentative estimates indicate that producers utilizing parasitoids spent more per cow on fly control costs than producers serving as a control but also had enhanced fly control. Dairies receiving parasitoids had only half the number of house flies on fly strips compared to control dairies. On the beef farm with fly traps, there was a 43% reduction in fly counts and a 30% reduction in costs for fly control. Moreover, the number of flies on the beef cattle never reached the economic threshold of 100 per animal with the fly trap but exceeded an average of 100 per cow for 6 of the 10 (60%) weeks for the control cows.
Farmer Adoption
Dairy producers in Washington County now are more knowledgeable of parasitoids and are more interested in the possibility of non-chemical fly control. They still need to have enough confidence in the parasitoids to treat only when fly populations reach a specified level so as to lower overall costs of fly control, the basic principle of IPM. We have two producers who have paid to utilize parasitoids and are not on the project. We asked the six original producers to pay 50% of the costs of the parasitoids this year and five agreed to do so. We later paid for 100% of the costs since the project had enough funds to do so. In central Arkansas, we had made a similar request and all agreed to pay for part of the parasites.
A success story of significant financial benefit to a producer occurred on one dairy which was utilizing extensive insecticides on his cattle, especially the calves, and had created an insecticide resistance problem. By using parasites and fly baits with a different insecticide, he reduced his pesticide use by an estimated 75% and reduced his fly problem. He also exposed his animals and his family to fewer pesticides.
Areas needing additional study
Although these results are favorable for the use of parasitoids to control house and stable flies on dairy farms, additional work specifically measuring the degree of parasitism by parasitoids is needed before we routinely recommend their use on dairy farms. Also, additional studies need to more closely define why fly parasites appear to work more effectively on farms with better cleanliness scores and in more convined failities. Use of a fly trap has potential to reduce horn fly numbers, but needs to be accepted by the producer before it is recommended for use.