METHOD AND PROCEDURE FOR EVALUATING BIOLOGICAL PERFORMANCE OF PHARAOH ANT, MONOMORIUM PHARAONIS (HYMENOPTERA: FORMICIDAE), BAITS

Abstract:
Pharaoh ants, Monomorium pharaonis, are significant pests associated with man and his environment. Chemical sprays are not ideal control methods if they cause the ants to disperse. There is a preference for bait treatments that provide a means to use ant biology to transfer slow-acting compounds into the nest and kill it at the source. Many factors can influence bait performance, including the feeding preference of the target species and the composition of the bait matrix. Since the majority of the bait is composed of various foodstuffs, the quality of those ingredients, and their attractiveness over time must be maintained. Correct bait placement, treatment density, monitoring are essential operational parameters, while any contamination of the bait stations, themselves may effectively repel ants, independent of the palatability of the bait matrix. A bioassay has been developed (based on the methods of Rupes) which allows rapid assessment of bait performance. New ant colonies are established in the main breeding culture and allowed to acclimatise for a week, or more, before introducing baits. These baits may be from production batches prior to distribution, or from the field, or may be new bait candidates (eg new formulations, or new active ingredients). By introducing the baits into a system where alternative food is abundant, and the ant colony is established, the conditions may be considered difficult, even in a confined space under laboratory conditions. Results to date show that where concerns have been raised about bait performance in the field, these are rarely attributable to the product itself (or alone). The test system has wider use as a model for establishing the bait potential of novel active ingredients since actively foraging colonies of a social insect can be established quickly and easily to determine such critical factors as repellency of the ai, delayed action, formulation palatability, behavioural effects on foragers and indirect effects via transfer of lethal doses to non-foraging stages.