Developmental Rates of the Hop Vine Borer and Potato Stem Borer (Lepidoptera: Noctuidae): Implications for Insecticidal Control

Abstract

The development of the hop vine borer, Hydraecia immanis (Guenee), and potato stem borer, H. micacea (Esper), was studied simultaneously under controlled laboratory conditions. Developmental thresholds for the egg, larval, and larval and pupal stages combined were determined using simple linear regression. These estimates (°C) for the eggs, larvae, and larvae and pupae combined were 8.45, 4.94, and 4.46, respectively, for H. immanis; and 6.83, 6.86, and 7.78, respectively, for H. micacea . Developmental times, expressed in degree-days above the appropriate threshold, were estimated also. Means for eggs, larvae, and larvae and pupae combined were 100.7, 741.8 and 1,186.8, respectively, for H. immanis; and 133.6, 522.2 and 756.5, respectively, for H. micacea . For both species, larval developmental times of females were significantly ( P ≤ 0.05) longer than for males. A mean H. immanis pupal weight of 567 mg was significantly ( P ≤ 0.01) higher than a mean H. micacea pupal weight of 478 mg. For both species, female pupal weights were significantly ( P ≤ 0.01) higher than male pupal weights.