Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2006
Publication Date: 5/1/2006
Citation: Curkovic, T., Brunner, J.F., Landolt, P.J. 2006. Courtship behavior in Choristoneura rosaceana and Pandemis pyrusana (Lepidoptera: Tortricidae). Ann. Entomol. Soc. Am. 99(3):617-624. Interpretive Summary: Because of continued concern with adverse environmental and human health effects of many pesticides in use, new methods and approaches are needed to control insect pests of vegetable crops. Sex pheromones for insect pests are useful for trapping or killing targeted species and are widely used tools in integrated pest management systems. Researchers at the USDA-ARS laboratory in Wapato, Washington, in collaboration with researchers at the Washington State University Tree Fruit Research and Extension Center in Wenatchee, Washington, are studying the use of sex pheromones of leafrollers in lure and kill products that can be used to reduce leafroller populations in apple orchards. Studies of close range attraction and courtship behavior of two leafroller pest species revealed the types of responses to be expected by males to synthetic pheromone lures, the courtship behavior that will get the males to contact formulations of pheromone and pesticide, and result in mortality of males in the field. These results provide important and useful information that will assist the design of the formulation, and the strategies of placement and densities of lure and kill droplets to be used in orchards to reduce populations of leafroller males.
Technical Abstract: The characterization of courtship behavior in two sympatric and synchronic leafroller species, C. rosaceana and P. pyrusana, indicated that only pheromone permeated airflow was needed as a releaser to initiate the male mating sequence. Mating ethograms demonstrate that males of both species perform six observable, discrete, and homogeneous steps: wing fanning, first contact, male next to female (mostly in C. rosaceana), head-to-head (mostly P. pyrusana), curbed abdomen, genitalia engagement, and end-to-end position (mating). Differences found in courtship behavior between species would help to avoid interspecific mating. The sequences were highly stereotypic, suggesting that once a male starts the mating sequence the rest of the steps will most likely follow. First contact with the female was a pre-programmed response, not requiring further cues. Copulation was significantly more likely when the female remained stationary after first contact. Unsuccessful mating sequences were frequent during studies because females escaped by walking away, turning around or jumping away. Since courtship behavior is a mechanism to select sexual partners, it is possible to hypothesize that responses resulting in an unsuccessful mating (assumed to be rejection) validate this mechanism. The mating sequence of C. rosaceana best matches the simple courtship behavior model, whereas the sequence in P. pyrusana resembles an interactive courtship. Overall results indicate that courtship behavior in both species would be compatible with attracticide (i.e. sex pheromone + insecticide) technology that requires direct contact between males and the source.