Progress 05/15/01 to 05/14/04
Outputs
Dung beetle species composition and seasonal distribution were studied within piedmont (Salisbury, NC) and coastal plain (Goldsboro, NC) regions of North Carolina. Dung beetles were trapped in cattle pastures from March of 2002 through September of 2003 using baited pitfall traps. Thirty were divided equally between a dairy in Salisbury and a dairy unit and a beef unit at Goldsboro. Trapping yielded 4,111 beetles and 14 species from the piedmont dairy. A total of 57,026 beetles representing 28 species and 28,857 beetles and 26 species was trapped from the dairy unit and beef unit in the coastal-plains, respectively. The introduced beetle Onthophagus taurus accounted for more than 50% of the beetles caught at both sites. Beetle activity was greatest from March until November of both years. Nine species in two genera, the Onthophagus and Aphodius, were exotic dung beetles and represented nearly 95% of the beetles trapped. Two species, Onthophagus gazella and Aphodius
prodromus, are new records for North Carolina. Dung beetle activity on soil nutrition was studied in three distinct soil types under laboratory conditions. O. gazella and O. taurus, were allowed to incorporate dung, for brood production, into a piedmont Cecil clay soil, a coastal plains sandy-loam soil and pure play sand. Soils were also exposed to dung alone to compare the effects of dung left on the soil surface. Beetles produced the most brood in the clay soil, with O. gazella producing an average of 92.0 total brood per 8 breeding pairs and O. taurus producing an average of 55.3 total brood per 8 breeding pairs. This study demonstrates an increase in primary and secondary nutrients, an increase in soil pH and an increase in the cation exchange capacity of soils in response to dung beetle activity. The electric walkthough fly trap reduced horn fly densities to below 200 flies per animal for 3 consecutive years. We also examined the use of methoprene, in an area-wide effort to
control the horn fly, was evaluated for non-target effects on dung beetle populations. Mixed breed cows and calves from ten adjoining farms, in Nash Co., NC, were treated with methoprene administered in a mineral formulation for 17 weeks during the summer of 2003. Horn fly densities on ten animals were determined weekly from each farm. Dung beetles were monitored every two weeks using dung-baited pitfall traps at two farms. Horn fly densities and dung beetle populations were compared to those from a pesticide-free farm in Wayne Co., NC. Methoprene reduced horn fly numbers below the control and the economic threshold of 200 flies per animal on the treated animals. A total of 26,775 dung beetles, representing 17 species, was trapped from Wayne Co. while 26,546 total dung beetles, representing 16 species, were trapped from Nash Co. The most common species at both sites included O. taurus, Aphodius pseudolividus, O. pennsylvanicus and O. hecate. Preliminary data show that methoprene usage
had no significant effect on these common Onthophagus species. The population of A. pseudolividus may have been reduced by methoprene, though it is not clear whether this species was naturally less common at the treated sites.
Impacts
Little was known of dung beetle ecology in North Carolina. Our study demonstrated that dung beetles were active year around and some species were very important for the decomposition of cattle dung providing essential nutrients to pasture grasses. Dung beetles play an important role in pasture ecology by competing with flies for available resources. Although these beetles help reduce fly densities their numbers are not great enough to control flies alone. Therefore insecticides may be necessary to help manage the flies. Traditionally, the use of insect growth regulators as a management tool, has not been satisfactory because of the need for cooperation between farms in the area. This project was the first area wide management program demonstrating the effective use of an IGR for the management of horn fly in North Carolina. The use of an insect growth regulator in combination with dung beetles appears to have minimal impact on these beneficial beetles. We also
demonstrated the effective use a the electric walkthough fly trap as a means of controlling horn flies.
Publications
- Bertone, M., W. Watson, M. Stringham, J. Green, S. Washburn, M. Poore, and M. Hucks. 2004. Dung beetles of Central and Eastern North Carolina Pastures. http://www.cals.ncsu.edu/entomology/guidetoncdungbeetles.pdf
- Bertone, M., J. Green, S. Washburn, M. Poore, C. Sorenson and Wes Watson. 2004. Seasonal activity and species composition of dung beetles (Coleoptera: Scarabaeidae and Geotrupidae) inhabiting cattle pastures in North Carolina (USA). Annuals of Ent. Soc. Amer. In Review (7/11/04).
- Watson, W. and M. Stringham. 2004. Face Fly, Musca autumnalis. Bulletin. http://www.cals.ncsu.edu/entomology/faceflybulletin.pdf
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Progress 10/01/02 to 09/30/03
Outputs
Objective. Determine the impact of Insect Growth Regulator (IGR) on dung beetle population densities in eastern North Carolina. Dung beetles reduce fly larval habitat by consuming or dispersing dung. Dung beetles fall into three basic nest building categories. Tunnelers consume the dung pat and burrow into the soil beneath the pat. Dwelling beetles consume the manure pat and deposit eggs in the manure, or in the soil near the surface. Dung rolling beetles tend to break the pat into brood balls that are rolled to a suitable site and buried. The IGR, methoprene mimics juvenile hormone and prevents the horn fly, a common pest of cattle, from reaching maturity. Administered as a feed through, some drug is excreted in the manure killing flies and some non-target insects. Ten adjoining cattle farms were identified to develop an area wide (19 sq. miles) study. Cattle were administered IGR mineral from June through September. Treated cattle were held on pasture separate from
the control group. Horn flies were counted on 10-animals from each farm to monitor changes in density. Fly populations were monitored for one week to establish pretreatment densities and weekly thereafter. Two treatment farms (A and B) were identified to monitor dung beetle activity. Ten pitfall traps were located on each farm A & B and C (control). Trapping occurred at 2-week intervals. Beetles were counted and identified to species. Fresh dung from treated and untreated cattle was collected and frozen. Thawed manure was used to bioassay the impact of methoprene on dung beetle development. Ten mating pairs of Onthophagus taurus were added to each pot. Pots were incubated for 35 days at 30oC. The number of adult beetles emerging and the number of brood balls in the soil were counted and held for emergence after 35 days. The IGR limited mean horn fly densities to below the fly threshold of 200 flies per animal. Fourteen species of dung beetles were collected from the three farms from
June 4 to September 23. Farms B and C produced the greatest number of beetles, 20,584 and 26,775 respectively. The fewest number of beetles, 5,963 were collected from farm A. Onthophagus taurus was the predominant species comprising 76, 85 and 70% of the beetles collected on farms A, B, and C, respectively. Onthophagus pennsylvanicus, accounted for 10% of the beetle population on both farms A & B but only 5% on farm C. Onthophagus gazella accounted for < 1% of the dung beetles on farms A & B and 4% on farm C. Aphodius lividus was found in greater densities on farm C (19%) than on the farms A & B (1-2%). Dung beetle populations peaked twice during the summer, July 16 and again on August 27. Increases were directly related to emerging O. taurus adults from two generations 40 days apart. If the IGR had a negative impact on the O. taurus population there would have been a decrease in second generation adults emerging August 27. Furthermore the negative effects of methoprene on O. taurus
was not evident in the laboratory study. Pots containing 10 mating pairs of adult beetles produced a mean of 30 brood balls with 90% adult emergence from both methoprene treated and untreated pots.
Impacts
Traditionally, the use of IGR as a management tool, has not been satisfactory because of the need for cooperation between farms in the area. This project was the first area wide management program demonstrating the effective use of an IGR for the management of horn fly in North Carolina. The use of an insect growth regulator in combination with dung beetles appears to have minimal impact on these beneficial beetles. Second season studies are needed to confirm results.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
An electric walk through fly trap was evaluated for the management of the horn fly, Haematobia irritans (L.) on dairy cattle in North Carolina over three years. The trap relies on black lights and electrocution grids to attract and kill flies that are brushed from the cattle passing through. During the first two seasons horn fly densities were reduced to seasonal mean densities of 269.2 + 25.8 and 177.3 + 10.8, respectively. Control cattle during the same period supported mean fly densities of 400.2 + 43.5 and 321.1 + 15.8, respectively. The 2002 seasonal mean horn fly density was much higher 405.15 + 64.7 for cattle using the walk through fly trap compared with on the control group 607.98 + 50.5. Similar fly densities were observed on beef cattle utilizing portable walk through fly traps powered by photovoltaic cells and a gasoline powered generator, respectively. No insecticides were used to control horn flies during this two-year study. A portion of this study is
focused on Dung Beetles (Coleoptera: Scarabaeidae and Geotrupidae) in cattle pastures and their role in fly management and pasture ecology. The objectives of this research were to determine what dung beetle species frequent cattle dung in North Carolina pastures and collect data on the seasonality of these dung beetles. Dung baited pitfall traps were designed to capture dung beetles. Ten (10) traps were located at the Piedmont Research Station (dairy unit) in Salisbury, NC, and twenty (20) traps were located at the CEFS farm in Goldsboro, NC (10 traps at the beef unit and 10 at the dairy unit). Trapping occurred over a twenty-four hour period every two weeks and started March 7, 2002. A total of 50,259 beetles representing 25 species were captured at Goldsboro, while 3,690 beetles representing 13 species were caught at Salisbury. Some species, such as Aphodius granarius and A. erraticus were present early in the season, but numbers declined later on in the season. Onthophagus gazella
was not present until the middle of the summer, and did not gain in numbers until the very end of the summer. Other species, however, were present much of the year in strong numbers (O. taurus, O. hecate, O. pennsylvanicus and A. lividus). Dung beetles have the potential to improve pastures through the incorporation of manure into pasture soils. This study determined the benefits of two species of dung beetles, Onthophagus gazella F. and Onthophagus taurus Schreber, on soil quality in the laboratory. Physical and chemical changes produced by the beetles were quantified. Test soil types were Cecil piedmont clay and coastal plain sandy-loam, common in central and eastern North Carolina, respectively. Play sand was used as a control soil. Treatments were bovine dung alone, dung plus O. gazella, dung plus O. taurus, and a no-dung control. The presence of beetles improved levels of P, K, Mg, and the sum of the cations in all soil types.
Impacts
The walk through fly trap has proven to be valuable tool in the management of horn flies without the use of insecticides. Although this year horn fly densities exceeded the desired threshold of 200 fly mean. The cause of this increase may be attributed to a number of factors; equipment failures, drought conditions, poor utilization of the trap and perhaps behavioral resistance in the fly population. Dung beetles, in the families Scarabaeidae and Geotrupidae, are important insects associated with vertebrate dung around the world. They consume large amounts of dung as adults and larvae. Their actions have been credited in reducing pasture fouling, adding nutrients to soil, aerating soil and competing for food resources with pestiferous flies (particularly the horn fly, Haematobia irritans (L.), and the face fly, Musca autumnalis DeGeer). We expect dung beetles to be an important contributor to the ecology and management of pasture ecosystems including pest management.
Publications
- Watson, D. W., S. M. Stringham, S. S. Denning, S. P. Washburn, M. H. Poore, and A. Meier. 2002. Managing the horn fly, Haematobia irritans (L.), Diptera, Muscidae, using an electric walk-through fly trap. J. Econ. Entomol. 95: 1113-1118.
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