Identification, distribution and temporal occurrence of aphids infesting large cardamom and their efficiency in transmitting large cardamom viruses in northeastern sub-Himalayan region

Abstract

Sikkim and Darjeeling hills of India are the largest producer and exporter of large cardamom. The two aphid-transmitted viruses, cardamom bushy dwarf virus (CBDV, genus Babuvirus) and large cardamom chirke virus (LCCV, genus Macluravirus), seriously affect the production of large cardamom. In the present study, three aphid species, Micromyzus kalimpongensis Basu, Pentalonia nigronervosa Coquerel and Aulacorthum solani Kalt. were identified and documented to colonize large cardamom in the different plantations based on survey, morphometrics and COI gene sequence-based phylogeny. A. solani was recorded in large cardamom for the first time in this study. The temporal occurrence and distribution of these three aphid species have been documented. M. kalimpongensis, a root feeding aphid was consistently present in large cardamom plantations throughout the year; predominantly on high altitude (>900 m) plantations. P. nigronervosa was predominant in plantations <1000 m altitude, and the population was higher during the summer season only. The incidence of A. solani was observed during the winter season only. All the aphid species infesting large cardamom were tested for their ability to transmit the two viruses, CBDV, and LCCV. Only, M. kalimpongensis but not the other two species of aphid could transmit CBDV to large cardamom. P. nigronervosa transmitted only LCCV, however, the rate of transmission was low. A. solani could not transmit any one of these viruses.