|Drew, Allison -|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2005
Publication Date: October 1, 2006
Citation: Smith, L., Drew, A.E. 2006. Fecundity, development and behavior of Ceratapion basicorne (Coleoptera: Apionidae), a prospective biological control agent of yellow starthistle. Environmental Entomology. 35(5):1366-1371. Interpretive Summary: Yellow starthistle is an alien weed that has invaded about 20 million acres in the western U.S. It is especially abundant in Pacific western states. The spiny plant interferes with grazing livestock and outdoors recreation,it is fatally poisonous to horses, and it outcompetes desirable vegetation. Six species of insects have been introduced as biological control agents, but they are not providing sufficient control. Foreign exploration in the Mediterranean Basin indicates that the weevil, Ceratapion basicorne, could be an important biological control agent. The insect attacks the roots of immature plants in the spring before the plant can reproduce. Little is known about the biology and host specificity of this insect because of the difficulty to obtain females that are ready to lay eggs. We successfully colonized this insect and collected fundamental information on its life history that provides a basis for conducting experiments to evaluate it as a potential biological control agent.
Technical Abstract: A laboratory colony of Ceratapion basicorne was established from adults reared from infested plants of yellow starthistle, Centaurea solstitialis, that were collected in eastern Turkey. All the adults emerged by July 1. The sex ratio of emerging adults was 54% female. Newly emerged adults fed on yellow starthistle foliage and mated, but females did not oviposit. The feeding rate of females decreased to zero 16 days after emergence, whereas males continued to feed at high rates for at least 26 days. Dispersal activity was initially high but decreased to low levels in 2-3 weeks. At the end of a 6-week observation period, most adults were hiding inside tightly curled dry leaves and in the crevices of crumpled paper towel, indicating that they were in diapause. Insects were held in a cold dark incubator (5°C) for at least 3 months to terminate diapause. Females began ovipositing soon after being placed on yellow starthistle leaves at 19°C. The oviposition period lasted 21 days, and lifetime fecundity was 34 eggs. Female feeding rate was highly correlated to oviposition rate, and both decreased after the first 2 weeks. Development time from oviposition until adult eclosion at about 19°C was 77 days.