Life cycle and biology of Pityogenes scitus Blandford, 1893 (Coleoptera: Curculionidae: Scolytinae), a pest of Pinus wallichiana in Kashmir, India

Abstract

The bark beetle, Pityogenes scitus Blandford, 1893 (Coleoptera: Curculionidae: Scolytinae) is one of the main pests in Pinus wallichiana A.B. Jackson, 1938 (Pinaceae) stands, and it has also been found on other Oriental Pinaceae species. This pest is aggressive and has caused significant loss of host trees, but little is known of its biology and ecology. Based on the field and laboratory observations, this study describes the detailed bioecology of P. scitus. This beetle pest overwinters in larval stage on blue pine (P. wallichiana) trees in Kashmir. After emergence, the adults fly to suitable trees and undergo maturation feeding for 4–6 days. Reproduction is polygamous type. After mating, each of the females makes one gallery with an average length 2.30 (± 0.41 SD) cm. The female lays 26.53 (± 6.32 SD) eggs on an average. The eggs hatch in 5 to 10 days. The larvae have 5 instars and complete their development in 18 to 28 days constructing larval galleries 1.76 (± 0.25 SD) cm in length. The larvae pupate for 13-22 days and finally the adults emerge to attack new suitable trees. The adults live for 28–40 days and the total life-span of this species ranges from 66 to 92 days. The seasonal distribution of various developmental stages and the number of generations were also recorded (5 generations (the last a partial one) per year in Kashmir). In general, the life cycle of P. scitus is similar to those described for other Pityogenes Bedel, 1 888 species.