From: Thatcher, Robert C., Janet L. Searcy, Jack E. Coster, and Gerard D. Hertel, eds. 1980. The Southern Pine Beetle. U.S. Department of Agriculture, Expanded Southern Pine Beetle Research and Applications Program, Forest Service, Science and Education Administration, Technical Bulletin 1631, p. 32-33.
The most common, colorful insect predator of SPB is the checkered or clerid beetle, Thanasimus dubius (F.) (Coleoptera:Cleridae). Clerid adults eat attacking SPB adults, and clerid larvae attack SPB larvae. This predator responds to SPB attractants and aggregates on trees undergoing mass attack by the beetle (Vite and Williamson 1970).
Hopkins (1899) first recognized T. dubius as a potentially important natural enemy of pine bark beetles. Several subsequent studies examined its biology, behavior, and impact on the SPB. Dixon and Payne (1979a) described the temporal and spatial distribution of T. dubius on SPB trees under attack in Texas. They reported peak numbers of clerids 1 day after peak SPB attack. Clerids were most abundant 4 days after initial SPB attack. Attacks by both SPB and the clerids lasted up to 11 days. Highest numbers of both were trapped early and late in the day in Texas and in Georgia (Dix and Franklin 1977). About 64 percent of both species were trapped on the lower half of the infested bole (Dixon and Payne 1979a).
Lenhard and Goyer (1980) reared T. dubius from log bolts taken during 1975 through 1977 in Louisiana. SPB activity was very high during this period. Clerids were found to be most active during spring and winter. Clerid densities did not strongly correlate with either SPB egg gallery length or bark thickness.
Frazier et al. (1980) described in detail the predatory behavior of adult T. dubius. They found that both sexes go through six typical behavioral acts as they prey on SPB. Frazier’s team determined the average time invested in each act and calculated the predator’s efficiency.
Studies of developmental rates of T. dubius revealed that immature stages developed more rapidly as temperatures increased from 12.5o C to 27o C (Nebeker and Purser 1980). Total developmental time (egg to adult) was the same whether clerid larvae were fed small or large SPB larvae or large pupae. But the prepupal and pupal periods were longer for clerids that had been fed on large SPB larvae and pupae.
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