Using Parasitoids in an Integrated Pest Management Approach to Control Flies on Dairy Farms

Using Parasitoids in an Integrated Pest Management Approach to Control Flies on Dairy Farms

Summary

During 2006 filth fly parasitism after releasing parasitic wasps was evaluated in Arkansas, Mississippi and North Carolina dairies to incorporate this technology into filth fly IPM. Baseline data collected in 2005 was used to establish timing and rates of parasite releases. Despite quality assurance issues with commercial parasites encountered during 2006, results were encouraging.

During 2006 and early 2007, results from this project as well as general IPM recommendations were presented to focus teams, dairy in-service trainings, dairy field days, professional meetings, and production meetings (i.e. organic dairy meetings). Also during 2006 several Arkansas dairies transitioned to organic production, these producers have been added as a target group for this project.

Tables, figures or graphs mentioned in this report are on file in the Southern SARE office.
Contact Sue Blum at 770-229-3350 or
sueblum@southernsare.org for a hard copy.

Objectives/Performance Targets

The overall purpose of this project is to develop a biologically based IPM program to manage house and stable flies on small and medium sized dairies. Studies during 2006 evaluated parasitoid dispersal and level of filth fly pupal parasitism after wasp releases were made on Arkansas, Mississippi, and North Carolina dairies. Parasitoids of both house and stable flies prevent parasitized fly pupae from emerging into adult flies. The project involves other IPM techniques such as manure management and judicious use of insecticides that are compatible with natural enemies such as pteromalid wasps.

The major research objective for 2006 was to evaluate the level of filth fly pupal parasitism after wasp releases on Arkansas, Mississippi and North Carolina dairies. Study locations selected in 2004 were used during the 2005 and 2006 fly season to collect data on parasitism levels. Rates and timing determined from baseline data collected in 2005 were used during 2006 studies. Dairies not receiving commercial parasites served as a control and were evaluated for natural parasitism in order to build upon data collected in 2005.

Another objective initiated in 2004 and expanded in 2005 and 2006 was the formation of focus teams to assist in development of outreach. Two teams of entomology and animal science specialists, county agriculture agents and dairy producers have been formed in the two major milk producing areas of Arkansas. These teams have now met numerous times and provided valuable insight into the most promising venue to reach dairy producers. They have also provided feedback related to IPM concerns (insecticide resistance in horn flies, insecticide labeling issues, and sanitation). During 2007, focus teams will help guide participants in production of the extension outreach component of the project. Most of this work is planned for 2007 and early 2008. Discussions have suggested that the extension component should be primarily electronic.

Data collected for dairies in 2005 was used to determine the release rates and timing of commercially pteromalid wasp releases made during the 2006 fly season. The overall IPM concept was incorporated with commercial wasp releases. These IPM techniques included population monitoring of fly pest species, establishment and use of treatment thresholds, limited use of insecticides that are compatible with natural enemies, and effective manure and waste management. Outreach components of the project will be conducted during the later stages of the project when firm release rate recommendations become available.

During 2006 sentinel house fly pupae and naturally occurring house and stable fly pupae were placed and/or collected from cooperating dairies selected in 2004 (Arkansas (4 dairies), Mississippi (2 dairies) and North Carolina (4 dairies)). The farms discussed in this report are labeled as follows: CA (release), NH (control) in Arkansas; FZ (release), CH (control) in Arkansas; MR (release), MSU (control) in Mississippi; JL (release), LW (release), MN (release), and NL (control) in North Carolina. All of the 2005 data and most of the 2006 data are completed. The sentinel and naturally occurring data from 2006 on dairies in North Carolina is still being analyzed.

Each farm’s total percent parasitism for both sentinel and naturally occurring pupae are shown by Table 1 for all farms in 2005 and Table 2 for Arkansas and Mississippi farms in 2006 (contact SARE for copy of tables). During 2005 the overall percent parasitism in sentinel pupae was 3.8% and 17.2% for naturally occurring pupae. Data from Arkansas and Mississippi for 2006 indicated the overall percent parasitism for sentinel pupae was 10.7%, and naturally occurring pupae was 13.1%. The increase of 6.9% parasitism in sentinel pupae from 2005 to 2006 was encouraging.

Table 3 (contact SARE for copy) shows the number and prevalence of parasitoids reared from sentinel Musca domestica pupae on all farms during April to October, 2005. Muscidifurax zaraptor parasitized the greatest number of sentinel pupae with 48.0% of the total number of parasitized. The number and prevalence of parasitoids collected from naturally occurring pupae of Musca domestica, Stomoxys calcitrans and blow flies (Family Calliphoridae) at five of the farms during May to October, 2005 is shown in Table 4. The greatest percent of naturally occurring pupae were parasitized by Spalangia cameroni with 21.0% of the total number parasitized. Table 5 shows the number of parasitoids collected from sentinel Musca domestica pupae each month from April to November, 2005 for all farms. The greatest number of parasitoids was collected during the month of July with a total of 645 parasitoids.

The total percent parasitism for sentinel pupae on each farm during 2005 and 2006 is shown in Table 6 (contact SARE for copy). During 2005 data was collected pre-release of parasitoids at farms CA and NH in Arkansas. The percent sentinel Musca domestica pupal parasitism in 2005 was 0.94% and 4.84% at the CA and NH farms, respectively. In 2006, parasitoids were released at CA and the percent parasitism was 12.80%. Farm NH, which was used as the control, had 10.50% parasitism during 2006. Data was also collected in 2005 at farms FZ and CH in Arkansas prior to wasp releases. During this year, 1.58% parasitism was found at FZ and 5.74% at CH. Parasitoids were released at FZ in 2006 resulting in 11.62% parasitism. The control farm CH had 4.96% parasitism during 2006. The farms in Mississippi also had data collected in 2005 pre-release of parasitoids. MR had 19.61% parasitism and MSU had 6.48% parasitism in 2005 prior to releases. During 2006 wasps were released at MR which had 23.60% parasitism during that year. MSU which served as the control farm had 8.55% parasitism in 2006. Three North Carolina farms received wasp releases during 2005. The percent parasitism of these farms was 5.91%, 2.54% and 3.62% for the JL, LW and MN farms respectively. The control farm, NL, had 2.65% parasitism during 2005. The 2006 sentinel data collected from North Carolina farms is still being analyzed.

Farms in Arkansas showed an increase from year 2005 to 2006 at farms where wasps were released, and resulted in a greater percent parasitism than control farms that did not receive releases of wasps. Mississippi showed a slight increase from 2005 to 2006 for both release and control farms, however the release farm was still greater than the control. In the parasitoid dispersal study two of the North Carolina release farms had a slightly greater percent parasitism than the control farm; however one farm was slightly lower in percent parasitism than the control. The data from North Carolina for 2006 that is still being analyzed will provide more results to consider and include in this table.

The total percent parasitism for naturally occurring pupae on each farm for 2005 and 2006 is shown in Table 7 (contact SARE for copy). During 2005, prior to the release of parasitoids, farm CA in Arkansas had 5.42% and NH had 4.03% parasitism. In 2006 parasitoid releases were made at CA and naturally occurring pupae had a18.64% parasitism rate. In contrast, NH farm, the control had a 9.36% parasitism rate during 2006. In 2005, pre-release of parasitoids, farm MR in Mississippi had 2.85% and MSU had 9.17% parasitism. After releases of wasps in 2006 the MR farm in Mississippi percent parasitism was 11.73%. MSU, Mississippi’s control farm, had 14.46% parasitism rate during 2006. Three North Carolina farms received parasitoid releases in 2005 to study parasitoid dispersal. At those farms receiving releases, the percent parasitism of naturally occurring pupae was 24.95%, 23.13%, and 27.67% at JL, LW and MN farms, respectively. NL was used as the control farm and had 31.15% parasitism during 2005. Data from 2006 are currently being evaluated.

Farms CA and NH in Arkansas showed an increase from year 2005 to 2006 at both control and release farms. However, the release farm had a higher percent parasitism in naturally occurring pupae than the control farm. Both control and release farms in Mississippi increased in the amount of parasitism from year 2005 to 2006, but the control farm had a greater percent than the release farm. All farms in North Carolina demonstrated moderate parasitism. The control farm in North Carolina had a slightly greater percentage than the three release farms. Preliminary data from sub samples of commercial parasitoids released at the study farms indicated a lower than normal emergence and parasitism rate. This resulted in a release rate less than one half the rate that was planned (200-250 per cow) resulting in lower parasitism rates at the “release” farms than was expected.

Figures 1 through 4 show the percent parasitism of sentinel and naturally pupae for each farm during 2005 and 2006 (contact SARE for copy). Pupal parasitism occurred throughout the fly season with the least amount of parasitism occurring early and in some farms late in the fly season. Readers interested in studying changes in parasitism rates through the season may contact SARE to obtain a copy of these figures.

Results from 2005 naturally occurring pupae and sentinel Musca domestica pupae indicate that similarities of species composition exist within differing geographical areas of the southern states. Data also show that differing methods (i.e. sentinel verse naturally collected pupae) may result differing species composition and abundance indicating that use of both methods will provide more reliable baseline data. Among the most abundant species occurring on south dairy farms were Muscidifurax zaraptor, Spalangia cameroni and Trichomalopsis sarcophagae. This indicates that these three species are suitable candidates for wasp releases. Figures 5 through 10 (contact SARE for copy) provide detailed information on the species composition and relative abundance of pteromalid wasps collected from dairies in Arkansas, Mississippi and North Carolina.

House fly (Musca domestica) abundance at two Arkansas farms is provided in Figures 11 and 12. House fly seasonal distribution in 2005 and 2006 was similar. CA farm (control) had consistently lower house fly abundance in 2005 (prior to releases) and in 2006 (during releases).

Principal investigators from Mississippi, North Carolina and Arkansas communicate frequently through telephone and email in addition to yearly meetings. On April 20 2006, principle investigators met through videoconference. This years meeting is scheduled for April 11 also as a video conference. During 2006 four focus team meetings were held to discuss progress of the project.

During the 2006 study, we purchased the number of parasitic wasps (as parasitized house fly pupae) to release 200-250 wasps per cow per week. Parasitized house fly pupae were obtained from a reputable insectary. However, the results from sub samples of each commercial parasitoid shipment revealed a lower percentage of parasitism and emergence than anticipated. Due to this problem, the emphasis on quality, and the need for sub-sampling have become evident. In 2007, we plan to continue research on the dairies in order to gain additional data at the release rate we initially planned. Discussions have been made with the insectary’s representative to remedy the situation. Preliminary plans to determine where problems may be occurring (shipping, etc.) include taking sub samples at the insectary prior to shipment and upon receipt. This will allow for early detection of any problems that may occur. Also, this situation has raised the issue of how producers can conduct quality assurance. Discussions will continue on this issue with the focus team. For 2006, percentages of parasitism in sentinel pupae and fly number data were still encouraging despite the low release rates that actually occurred. Demonstrations and further research will allow for more accurate data to be collected on parasitism by wasps being released at the rate we project (200-250 per cow per day).

Accomplishments/Milestones

Data on the species composition and abundance of naturally occurring parasitoids was collected again during the 2006 fly season. This data provided valuable information that will add to the data collected from 2005 and help provide recommendations concerning fly IPM for southern dairies. Commercial parasitic wasp releases were made in 2006 and compared to control farms and to the previous year. The preliminary data provided in this report are encouraging (increased percent parasitism on “release” farms) despite releasing much fewer wasps than expected. This data is essential in determining initial parasitoid release rates and timing for IPM studies for demonstrations in the 2007 fly season and devising quality assurance methods that can be adopted by producers.

Two focus teams consisting of entomology and animal science specialists, county agriculture agents and dairy producers were formed in the two major milk producing areas of Arkansas in 2005 and met during 2006. These teams have met several times and provided valuable insight into the most promising venue to reach dairy producers. Their input and feedback will be valuable in conducting the major dairy/IPM outreach component of the study scheduled for 2007.

In 2006, several small scale conventional dairies have transitioned to organic production. In a very short time period organic dairy producers have become the most vocal proponent of this project. This production system allows for very limited use of insecticides (some botanical and bacterial insecticides) which limits fly IPM methods to primarily biological control, sanitation and trapping. Arkansas extension has been involved in the initial planning phases of transition and farm planning associated with these new organic dairies. This has provided us with an opportunity to meet and discuss this project with producers both on site and in several organized meetings. As a result we have numerous dairies interested in participating in IPM demonstrations directly related to this project as well as projects for managing other pests such as horn flies. Some organic dairy producers in southern Missouri also attend Arkansas meetings. As a result we get inquiries from these Missouri farms anxiously awaiting recommendations resulting from this work.

Impacts and Contributions/Outcomes

Preliminary results from this project as well as general dairy IPM recommendations have been presented in numerous venues during 2006 and the beginning of 2007 (agent in-service training, yearly dairy field day, organic production meetings, demonstrations in organic dairy, and demonstrations in small scale swine and horse stables as well as professional meetings (Entomological Society of America and Southern Dairy Conference)). Additional presentations will be made during the remainder of 2007 and educational outreach materials will be created through input from the focus teams. News releases related to this project and fly IPM were prepared and released during 2006.

Also an interest in dairy/fly IPM using parasitoids has increased as a result of local interest in organic milk production. In an April 2006 meeting, producers attending these organic production meeting have been informed of this project and have expressed interest in using IPM and parasitoids as a means of reducing pesticide usage to comply with the organic production guidelines. One producer transitioning to organic production began using parasitoids and IPM for house and stable fly control. IPM/parasitoid demonstrations at this dairy and at least one other newly transitioned organic dairy are planned for 2007. The number of IPM/parasitoid demonstrations may expand as additional dairies transition into organic production and project updates are presented during 2007 dairy meetings.

Data from 2005 and 2006 have shown producers the importance of sanitation in any fly management program. One very important outcome from 2006 is the importance of quality assurance. Some producers have been shown data from 2006 and are very receptive in accessing the quality of parasitoids through sub sampling. Development of an assessment method that producers can easily employ to determine percent emergence of commercial parasitoid shipments is high priority for 2007. Focus team members were shown that house fly numbers from sticky ribbons were much higher on farms that had an abundance of fly breeding material. This helped illustrate that sanitation is the most important component in managing house flies in animal or milk production systems and that any management system used must incorporate sound sanitation practices. Data from 2006 parasitoid shipment sub sampling indicated the importance of parasite quality and the need to develop an easy procedure for producers to monitor quality.

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