POPULATION DYNAMICS OF PREDATORS OF BARK BEETLES (COLEOPTERA: CURCULIONIDAE: SCOLYTINAE) INFESTING PINUS WALLICHIANA IN KASHMIR, INDIA

摘要

Natural enemies especially predators are known to be an important factor in the population density regulation of bark beetles. In present study, population dynamics of predators ofbark beetles (Coleoptera: Curculionidae: Scolytinae) living associatedon Pinus wallichiana A. B. Jacks (Pinaceae) in Kashmir, India, has been studied. The samples were collected for a period of two years (from April to November 2015 and from April to November 2016) with the interval of 15 days between the successive sampling instances. Three bark beetles viz., Ips stebbingi Strohmeyer, 1908, Polygraphus major Stebbing, 1903 and Pityogenes scitus Blandford, 1893 have been reported to attack Pinus wallichiana in Kashmir for the first time. Four species of predator were found associated with these bark beetles. Niponius canalicollis Lewis, 1901 was observed as the predominant predator during 2015 with coefficient of dominance 36.93% followed by Platysoma rimarium Erichson, 1834 with dominance coefficient of 27.15%. However,during 2016, P. rimarium was reported as predominant predator with coefficient of dominance 32.4% followed by N. canalicollis with dominance coefficient of 28.13%. The dominance coefficient of Thanasimus himalayensis Stebbing, 1914 was 20% (2015) and 26.66% (2016). The least dominant species was Corticeus flavipennis Motschulsky, 1859 with dominance coefficient of 15.91 % (2015) and 12.8% (2016). All predator species treated in this paper are found to be generalist predators ofbark beetles as all of the extant species are reported from more than two species of beetle pests. The significant number of predators observed in the bark beetle galleries and on the infested host material supports the fact that they can play a major role in the regulation ofbark beetle populations. This has relevance to pest management strategies in the forests. P. scitus is also reported as a new host range of N. canalicollis.