Identification of coprophagous and nematopredacious arthropod species present on farms in Arkansas.
A characterization of the caprophagous and nematopredacious arthropod species found in different regions of Arkansas. Additionally, seasonal species changes were tracked. Locations showed different abundances of species. Shirley, AR, area showed more diversity of species than other locations. Armadillidiidae (roly poly) were found in Marshall, AR, area and Shirley, (both northern Arkansas) with higher populations in Marshall. De Queen, AR, (western Arkansas) area possessed medium-sized scarabidae (dung beetles) not found in other areas. Fire ants were also common in DeQueen. Grapevine, AR, (Southern Arkansas) area showed Phanaeus vindex that were not found elsewhere, and much larger dung beetles in general.
Haemonchus contortus, the barberpole worm, is a blood-sucking gastrointestinal parasite of special importance in small ruminants. Goats infected with H. contortus suffer from reduced productivity, anemia, and eventually death. Due to the overuse of chemical dewormers, H. contortus has become resistant to all available classes of dewormers (Terrill et al., 2001; Zajac and Gipson, 2000). FAMACHA scoring and treating only those animals with high scores for anemia will reduce the rate at which complete resistance of H. contortus to chemical dewormers occurs, but it is labor intensive (Van Wyk and Bath, 2002). Moreover, once chemical dewormers are no longer capable of controlling H. contortus infections, H. contortus has the potential to wipe out the small ruminant industry in the southeastern United States. Mortality rates as high as 20% have been reported in parts of the world where H. contortus is completely resistant to chemical dewormers.
The life cycle of H. contortus begins with the egg, which passes out of the host animal in the feces. The egg hatches and undergoes two stages of larval development before reaching the migratory third instar (L3). The L3 larva crawls up grass blades to a height of usually no more than 2-3 inches and waits to be consumed by a host animal. Once inside the host, it completes its molt to a stage 4 larva, and eventually an adult, blood-sucking worm which repeats the cycle.
Alternative methods of controlling H. contortus infections include the use of forages high in tannins, copper oxide wire particle boluses, selective breeding, rotational grazing and maintaining pasture forage heights above 4 inches (Fleming et al., 2006). No one of these methods is capable of completely controlling H. contortus. Alternative methods will have to be part of a comprehensive integrated pest management (IPM) program designed to reduce H. contortus infection rates to manageable levels. Development of additional H. contortus control strategies is necessary to protect small ruminant producers in the southeastern United States against unsustainable economic losses due to gastrointestinal parasites.
H. contortus and other internal and external parasites such as horn flies(Haematobiairritans), face flies(Muscaautumnalis) and coccidia rely on feces at some point in their life cycle either as a source of nutrients or as a carrier for passage out of the host into the environment. Reduction of fecal material on pastures could reduce the parasite egg load on the pasture. Most methods of manure management on pastures require a tractor to pull a harrow or similar object over the pastures to break up manure to speed drying and expose parasites to predators and the elements.The drawback to this method is that it is time-consuming and increase fuel and equipment maintenance costs. Alternatively, predators of nematode larvae that live on or near manure may be useful in reducing the number of H. contortus larvae surviving to migrate to nearby grasses where they can be ingested and start the cycle of infection again.
To determine the presence and distribution of caprophagous and nematophagous arthropod species on small ruminant farms in Arkansas.
Cooperating farmers were trained in FAMACHA scoring and fecal egg counting techniques at the beginning of the project by Dr. David Fernandez, UAPB Extension Livestock Specialist, so they can track parasite infection rates in their goats. Cooperators learned to keep accurate monthly records of FAMACHA scores, fecal egg counts, and deworming schedules. Cooperators were to keep a log of local weather conditions updated daily to account for possible effects on parasite and manure-living species of interest to the study. Dr. Gekara, Faculty Director UAPB livestock operations, was to ensure that similar records were collected on goats housed at the University farm.
Arthropod traps described by Bang, et. al. (2005) were constructed and transported to each cooperator’s farm. In March of the first year, Drs. Fernandez and Park assisted cooperators identify suitable trapping locations and install traps. Dung beetles were trapped using the method of Bang, et. al. (2005) in April, June, August and October.
Seventy two hours before dung beetles were trapped, fresh goat feces (500 g) were be placed on three 20 x 20 cm plots by 8:00 AM. Earth to a depth of 20 cm was removed from each plot 72 hours later and earthworms were collected. A similar sample was collected from three 20 x 20 x 20 cm plots nearby as a control sample. Earthworms were quantified and categorized by size.
Dr. Fernandez assisted cooperators in collecting arthropods from traps and transporting them back to the entomology lab at UAPB for identification and quantification. Arthropods that comprise the largest proportion of those arthropods collected from each farm were to be propagated for catch and release to supplement the natural population in year 2.
During year two, selected arthropods were to be released on the farms from which they were collected. Seasonal variations, if any, in arthropod populations from year 1 were to be mimicked in year 2. Farmer cooperators were to continue to keep records of FAMACHA scores, fecal egg counts and deworming schedules, as well as a weather log.
Due to a power failure and the resulting deterioration of specimens, we are still in the process of identifying all of the arthropods caught in the traps. Farmers also did not collect weather and parasite data.
Preliminary analysis demonstrate that during the winter, farms in north Arkansas had beetles of the Aphodius genus and that they were more prevalent at higher altitude (Shirley vs. Marshall). Aphodius genus were not present in Violet Hill, which was even further north, but only one year’s worth of data were available for this farm because the farmer exited the small ruminant business. Aphodius genus were not present in western (DeQueen) or southern (Grapevine) Arkansas. In western Arkansas, beetles were primarily Scarabidae.
Summer trappings revealed only Phanaeus vindex (orange/green dung beetle) and various ground beetles present in southern Arkansas traps. Medium-sized Scarabidae were present in western Arkansas. Traps in northern Arkansas were destroyed by insectivorous predators.
In fall, higher altitude traps in northern Arkansas were unique compared with other areas. The Aphodius genus was different from other locations, and the Scarabidae in northern Arkansas were both larger and nine times more abundant than in southern Arkansas.
Overall, each location showed a different abundance of dung beetles of differing genera. There was a greater diversity of species at the highest altitude traps in northern Arkansas than at any other location. Phanaeus vindex were only found in southern Arkansas.
This study demonstrates the need to release species of caprophagous or nematophagous species in areas where they are well-adapted. It is not expected, for example, that Phanaeus vindex will survive on northern Arkansas farms.
Educational & Outreach Activities
An abstract will be presented at the ARD meeting in Atlanta in spring of 2017. Upon completion of the analysis, a manuscript will be presented for publication and a fact sheet will be prepared for distribution to Extension agents in Arkansas. One Master’s thesis will also result from the completed project.
We expect farmers will adopt management practices that will conserve or increase the number and diversity of caprophagous and nematophagous species on their farms.
Farmers should reduce the use of anthelminthics on their farms. Anthelminthics have been shown to reduce the survival of some caprophagous and nematodophagous species. Using an integrated pest management approach will not only increase the abundance and diversity of these species, but will also slow the development of parasite resistance to anthelminthics.
Areas needing additional study
Future research needs include development of methods for breeding caprophagous and nematophagus species for release on farms, greater specificity of identification of appropriate locations for release of the appropriate species for control of nematodes and additional methods to improve the survival of caprophagous and nematophagous species on small ruminant farms.