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Evaluation of Seasonal Variations in Carcinops pumilio Dispersal and Potential for Suppression of Dispersal Behavior 2000

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Project leaders: D. A. Rutz, P. E. Kaufman, AND S. J. Long, Department of Entomology; and J. K. Waldron, NYS IPM Program, Cornell University, Ithaca, NY

Cooperators: John Gingerich, Egg Farm Division, Wegmans Food Markets, Wolcott, NY

Abstract:

Seasonal dispersal of Carcinops pumilio collected using two trapping methods, the Hister House™ and a black light pitfall trap were examined in the laboratory. The black light trap had a numerical collecting advantage over the Hister House™ from March through June. The Hister House™ gathered larger numbers of beetles from June through August and demonstrated less variability throughout the year. During the winter months, beetle collections with both trapping methods were commonly low. These data also document that even when very low numbers of beetles were recovered from manure cores, large numbers of beetles could be collected with the black light trap. This also suggests that beetle density may not be an important factor affecting initiation of dispersal behavior.

Beetles captured with the two trap types had initial dispersal patterns that were significantly different from each other. Carcinops pumilio dispersal was partially explained by the month in which the beetles were collected. However, significant interactions were also observed between the three month effects and both trap type and the trap collection level. Therefore information on multiple effects are needed to fully explain C. pumilio dispersal and potential for field collections.

The greatest dispersal (~90%) in the arenas occurred with beetles collected using both trap types in June 2000. Regardless of trapping method, laboratory dispersal and beetle collections declined from June through October 1999. Following the decline in both trap captures and dispersal rates of beetles in laboratory arenas, we observed a sharp rise in dispersal arenas during November and December 1999. This was followed by a depression of dispersal in January and February 2000. Similar to the trend observed in 1999, beginning in March and ending in August 2000 a rise and then fall pattern in both laboratory dispersal and beetle collections was observed. Although the magnitude of the trap captures in 2000 was not repeated, trap collection patterns were similar to those observed in 1999.

Varied dispersal responses were observed among the beetles exposed to "altered" daylength and feeding regimes. In January and March significantly fewer original cohort black light-collected beetles dispersed than those exposed to a decreasing light regime (held in incubator). In contrast, significantly fewer May-collected beetles dispersed after placement in the incubator where they also received continually shorter daylengths. This suggests that in January and March, we were unable to prevent recruitment of beetles into dispersal behavior, however, in May, after beetles have been in a dispersal phase for several months, we were able to suppress dispersal. In contrast, dispersal behavior among beetles captured with the Hister House™ did not significantly change following the photoperiod-altered exposure. The interaction of the altered photoperiod and month effects were not significant, suggesting that beetles attracted to or captured by these traps were influenced by other factors.

These results are especially important to producers who want to maximize trapping efficiency and retain the beetles that they introduce to a facility. Because both the type of trap they were collected with and the collection time of year drive beetle dispersal, producers can use this knowledge to either target specific pest problems or as a component in a general pest management program.