Biology and natural control of the white pine weevil, Pissodes strobi (Peck), in Virginia

Abstract

Ovariole development and termination of diapause in the white pine weevil were studied by dissecting weevils at various intervals throughout the winter. Old-generation adults brought into the laboratory November produced viable eggs within 5 days. New generation adults brought into the laboratory on November 4 produced viable eggs during November. Viable eggs were deposited by other new-generation adults after 10 to 15 day. at room temperature in winter. On each of the 3 collection date studied, new generation adult produced viable eggs without copulating after collection from hibernation indicating that capulation occurs in the fall. There was no evidence of progressive ovariole development throughout the winter. New generation adults which were isolated as soon as they emerged from the shoots and maintained at constant room temperature had poorly developed ovarioles by November 20 and produced no eggs. Weevil flight and dispersal through a white pine plantation was studied by releasing 409 marked weevils at a central point within a l431-tree plantation and checking every tree at 5-day intervals. Weevils flew readily at the time of re1ease. Marked weevils were recorded throughout the plantation. which extended as far as 330 feet from the release point. A few weevils were observed on scattered white pines 200-300 yards from the release point beyond a hardwood barrier. Total numbers of weevils present on the leaders increased from April 26 to May 5, after which numbers steadily decreased. By June 15, only 20 weevils were observed on the leaders.