Biological and ecological studies of Hydrotaea aenescens (Wiedemann) (Diptera: Muscidae), and other arthropods of high-rise cage layer poultry houses

Laboratory and field studies of Hydrotaea aenescens were undertaken to provide information on this predator's biology and ecology under differing conditions, and to promote its use as a biocontrol agent for controlling house flies in poultry houses.

Taxonomic diversity of arthropods in a new high-rise cage layer poultry house was determined from manure samples collected from different manure moisture categories. Stabilization of taxonomic diversity and taxonomic evenness of manure-inhabiting arthropods occurred after the house had been operating for eight months. In contrast, overall diversity in high-rise poultry houses at a well managed, longer established farm was significantly higher than that observed at the new farm, even after 1 1/2 years of operation.

When the densities of selected manure-inhabiting predatory arthropods collected from the manure samples (including Carcinops pumilio, pseudoscorpions, a dermapteran species, an anthocorid species, and H. aenescens) were correlated with percent manure moisture, the results showed that, of these predators, only H. aenescens was positively correlated with both manure moisture and with densities of house fly larvae. This information emphasized that although predators such as C. pumilio may exhibit high predation rates on house fly eggs and first instars, their effectiveness 1s reduced by their spatial separation from their supposed prey. This contrasts greatly with H. aenescens performance.

Decreases in survival of house fly larvae occurred when the larvae were exposed to H. aenescens of higher larval stadia. This was dramatically demonstrated when 100 first instar house flies were exposed to 100 second instar H. aenescens. No house fly larvae survived.

Developmental times were determined at constant temperatures for egg, and larval H. aenescens. Developmental times decreased as temperature increased. Median time for egg and larval development ranged from 1.3 and 14.6 days at 22.2°C to 0.5 and 8.3 days at 35.0°C, for the respective stages.

All of this information, together with developmental times and mortality of H. aenescens immatures gathered in a study of temperature dependent development has enhanced understanding of the biotic interactions in accumulated poultry manure. These data will be invaluable in designing integrated pest management programs especially in the area of computer-aided decision making.