PROLONGED DORMANCY IN A PACIFIC NORTHWEST POPULATION OF THE COLORADO POTATO BEETLE,LEPTINOTARSA DECEMLINEATA(SAY) (COLEOPTERA: CHRYSOMELIDAE)

Abstract

The Colorado potato beetle is a major worldwide pest of potato and several other solanaceous plants. Insecticidal resistance is a serious problem in the northeastern and mid-Atlantic regions of the United States and a developing problem in other potato production areas of the United States and Canada (Forgash 1985; Johnson and Sandvol 1986; Boiteau et al. 1987). In the northwestern United States, insecticides applied to control the green peach aphid also control Colorado potato beetle, but these insecticides are likely to become ineffective due to the development of resistance or unavailable because of restricted use and environmental concerns. Biologically based management strategies are needed to reduce dependency on insecticides; these strategies require new basic knowledge including understanding prolonged diapause in populations of the Colorado potato beetle. Krysan et al. (1986) established that the occurrence of prolonged or repeated diapause can influence management strategies for insects, especially with respect to crop rotation.

Prolonged Dormancy inLeptinotarsa decemlineata(Coleoptera: Chrysomelidae): A Ten-Year Field Study with Implications for Crop Rotation

“…Following the above lines, Biever and Chauvin (1990) explained the remarkably high incidence (22%) of prolonged dormancy in Colorado potato beetles from western United States, and our data here are consistent with their explanation. Beetles in western United States commonly occur on wild (weedy) solanaceous host plants in their drought-prone native habitat (Hsiao 1978, Biever andChauvin 1990); thus, a high propensity for prolonged dormancy would be advantageous.…”

“…At least one beetle in our study remained dormant for 9 yr, others for up to 7 yr. Previously, Ushatinskaya (1966b) and Biever and Chauvin (1990) recorded dormancy of 3 and 5 yr, respectively, in populations from the Transcarpathian region of the former USSR and from Washington State. These periods are of considerable duration, but by no means, are they especially long among insects (e.g., Powell 1989).…”

“…Beetles in western United States commonly occur on wild (weedy) solanaceous host plants in their drought-prone native habitat (Hsiao 1978, Biever andChauvin 1990); thus, a high propensity for prolonged dormancy would be advantageous. In contrast, the incidence of prolonged dormancy is relatively low in populations that were introduced with cultivated potato plants into eastern Europe (Ͻ1%) (Ushatinskaya 1966b).…”

“…Thus, the overwintering population is composed of beetles from early and late summer generations, as well as those from early autumn. Some (but certainly not all) beetles enter prolonged dormancy, i.e., they undergo diapause in the soil for Ͼ1 yr (Isely 1935, Ushatinskaya 1966b, Biever and Chauvin 1990.…”

Colorado Potato Beetle Resistance to Insecticides

“…Similarly, between 0-7.2% of beetles in upstate New York emerged after more than one winter in dormancy (Tauber and Tauber 2002). Incidence of prolonged diapause was even higher in Washington State, where 16-21% of overwintering adults emerged after two winters, and up to 2% emerged after three winters (Biever and Chauvin 1990).…”