Effect of Temperature on Fecundity and Survival of Chrysolina quadrigemina (Suffr.) and C. hyperici (Forst.) (Coleoptera: Chrysomelidae)

Abstract

Four colonies of Chrysolina quadrigemina (Suffr.) and two of C. hyperici (Forst.) were released in 1951 and 1952 in the souvhern interior of British Columbia (Fig. 1) in the hope of duplicating the successful biological control of Hypericum perforatum L. in California. In 1956, Smith (1958) showed that though the colonies were still present, the weed had increased in all areas. By 1960, however, C. hyperici had greatly reduced the abundance of H. perforatum at Fruitvale (Fig. 2) while at Edgewood the beetle had disappeared. A colony of C. padrigmina at Edgewood had also disappeared and the three other C. quadrigemina colonies persisted at a low density without controlling the weed. For example, at Christina Lake (Fig. 3) a few beetles were found every year since release, though they had not always appeared in the sample plots. The annual fluctuations of the weed as indicated in the figure were probably of climatic origin as they were similar to those for the other areas. The most promising of the C. quadrigemina colonies was at Fife where, though there were few beetles in the release meadow itself, they were common on the slope below.