Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2008
Publication Date: 10/1/2008
Citation: Sarvary, M.A., Hight, S.D., Carpenter, J.E., Bloem, S., Bloem, K.A., Dorn, S. 2008. Identification of factors influencing flight performance of field-collected and laboratory-reared, overwintered, and nonoverwintered cactus moths fed with field-collected host plants. Environmental Entomology. 37(5):1291-1299. Interpretive Summary: A moth native to northern Argentina was found in North America for the first time in 1989. This moth is damaging only to prickly pear cactus. The insect’s spread from the Florida Keys along the coast of southeastern United States to Alabama and South Carolina has raised concerns about this moth’s unavoidable and unwanted impact on native, agricultural, and ornamental cactus in its new homeland. The bright orange-red, black-spotted caterpillars are eating all species of prickly pear cacti with flat pads. Scientists with USDA Center for Medical, Agricultural and Veterinary Entomology in Tallahassee, FL and Crop Protection and Management Research Unit in Tifton, GA are looking into ways of controlling this insect in urban, agricultural, and natural settings. Experiments were conducted on the flight capacity of adult cactus moths. Comparisons were made between insects from the spring generation and adults from the summer generation. Spring flying adults were derived from caterpillars that spent the winter slowly developing on slow growing cactus whereas caterpillars of the summer flying moths rapidly developed under higher temperatures and on rapidly growing cactus plants. There were no differences between the flight capacity of females versus males. Although females from the spring generation were larger than females from the summer, they did not differ in their flight capacity. Mated females also flew the same as unmated females, suggesting that mated females may play an important role in invading new habitats. Male moths from the spring generation flew longer distances than males from the summer. This is advantageous for the overwintered cactus moth males to locate females in the spring when the insects are more patchily dispersed than other times of the year.
Technical Abstract: Environmental conditions during egg and larval development may influence the dispersal ability of insect pests, thus requiring seasonal adjustment of control strategies. We studied the longest single flight, total distance flown and the number of flights initiated by wild Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) to determine whether the flight performance of overwintered cactus moths with a prolonged feeding phase during development differs from non-overwintered cactus moths. Pupae of field-collected and laboratory-reared moths were transported together from the USA to Switzerland and flight mills were used to characterize the flight capacity of 24 to 48 h old adults during their most active period of the diel cycle. The lack of seasonal variation in flight performance of those moths that developed under controlled environment but were fed with field-collected Opuntia cacti showed that seasonal changes in host plant quality did not affect flight. This consistent flight performance in the mass-reared laboratory population throughout the year is beneficial for Sterile Insect Technique (SIT) programs, which aim to limit the dispersal of this pest. For field-collected C. cactorum the larger overwintered females performed similarly to non-overwintered females, indicating that longer feeding time at lower temperatures increases body size but does not influence female flight capacity. Young mated females had a similar flight capacity as unmated ones, suggesting that gravid females may play an important role in invading new habitats. For males, overwintering increased the proportion of long distance flyers, suggesting that they are well-adapted to locate the more sparsely dispersed females in the spring.