Investigation of Potential Biological Control Agents for Internal Parasite Control in Goats

• 2013 annual report
• 2014 annual report

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.

Introduction

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.