The biology and control of the pecan weevil, Curculio caryae (Horn) in Texas

The biology and control of the pecan weevil, Curculio caryae (Horn), was studied at Junction, Menard, and College Station, Texas, 1965-69. Data from field and laboratory studies were used to compute life tables for the various developmental stages of this insect. The duration of the egg stage at 25°C in the laboratory averaged 9.8 days. Larvae were successfully reared on an artificial medium in the laboratory. Larval head capsule measurements revealed that both field collected and laboratory reared larvae underwent 4 successive instars. The total larval feeding period was approximately 30 days in duration. The duration of the pupal stage ranged from 14 to 25 days and averaged 19.1 and 20.3 days for males and females, respectively, when held at 25°C in the laboratory (1967). The average duration of the pupal stage was 18.1 days for both sexes in the 1968 study. Approximately 90% of the larvae pupated 1 year after entering the soil and the remainder pupated the following year. Studies on the subterranean portion of the life cycle revealed that the larvae burrow into the soil to an average depth of 6 in. Approximately 90% of the larvae which entered the soil in Nov., 1966, pupated during Aug. and Sept., 1967, with 10% remaining as larvae until the following summer. After transformation from the pupal stage, the adults remained in the soil until the following Aug. and Sept. Only 4% of the initial insects successfully emerged as adults with the greatest mortality occurring in the pupal and adult stages. The number of eggs deposited/female ranged from 28 to 49 in 1967 and from 26 to 79 in 1969 with averages of 34.7 and 54.7, respectively.