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Title: Three-dimensional orienation by male Cadra cautella (Walker) flying to calling females in a windless environment

item Mankin, R W
item Hagstrum, D W

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/1995
Publication Date: N/A
Citation: Mankin, R.W., Hagstrum, D.W. 1995. Three-dimensional orienation by male Cadra cautella (Walker) flying to calling females in a windless environment. Environmental Entomology. 24:1616-1626.

Interpretive Summary: Sex pheromone traps are used as tools to monitor and pinpoint insect infestations in warehouses, but the searching mechanisms used by insects to locate a pheromone source are not well understood. Scientists at the USDA-ARS Insect Attractants, Behavior, and Basic Biology Research Laboratory in Gainesville, Florida and the Grain Marketing Research Laboratory in Manhattan, KS, have videotaped and analyzed insects searching for mates in three dimensions to describe searching mechanisms in more detail and determine the distances from which mates can be located. The results indicate that mates can be located from only about two-three feet if no wind is present because the insect has no wind- direction cues to guide it towards the sex pheromone source. The results support the hypothesis that pheromone traps work best in a warehouse if large numbers of small traps are placed where the insects are flying. In this way the traps serve to pinpoint the locations of infestations. These results are of benefit to warehouse pest control personnel seeking the best way to place and use pheromone traps.

Technical Abstract: A male C. cautella flying in a windless environment first reacts behaviorally to the sex pheromone plume of a calling female from a distance of about 40 cm. Its angular velocity (turning rate) increases and, if it approaches within about 20 cm, its velocity decreases gradually until it lands near the female. The orientation pattern differs from orientation in wind (pheromone-stimulated optomotor anemotaxis) primarily in the fraction of turns with net movement away from the female, initially about 0.5. This fraction decreases to about 0.2 if the male approaches within about 10 cm. Previously developed computer models indicate that such behavior is less efficient for locating a pheromone source than upwind anemotaxis but more efficient than random search. It thus can be expected that pheromone traps are less effective at sampling remote populations of insects in a warehouse than in a field, but nevertheless are helpful in pinpointing nearby infestations.