A new species of entomopathogenic nematode Oscheius gingeri sp. n. (Nematoda: Rhabditidae) from ginger rhizosphere

Abstract

A new species of entomopathogenic nematode (EPN) of the genus Oscheius was isolated from the rhizosphere of ginger (Zingiber officinale Rosc.) cultivated in Indian Institute of Spices Research Experimental Farm, Peruvannamuzhi, Calicut District, Kerala, India. This species is described as a new species on the basis of morphometrics study. Entomopathogenicity of this nematode was also tested against greater wax moth Gallaria mellonella larvae. O. gingeri sp. n. is diagnosed by the presence of leptoderan bursa and crochet needle-shaped spicules, presence of 10 lateral lines, didelphic female reproductive system, double-flapped epipytigma and nine genital papillae. The characteristics of the new species are: male; body ventrally curved, “C”-shaped upon fixation, leptoderan bursa, tail short rounded conoid and nine pairs of genital papillae, female; body almost straight upon fixation, female reproductive system is didelphic, double-flapped epipytigma present on the vulval opening and tail is short conoid with pointed tip and infective and juvenile; body thin elongate, tail elongate attenuated, gradually tapering at tip and spine-like projection present. It closely resembles with O. carolinensis but differs in smaller length (vs. L= 1728 μm), larger “a” value (vs. a = 18.2); smaller “b” value (vs. b = 7.0); and larger “c” value (vs. c = 11.0), vulval opening (vs. V= 50.3%), number of lateral lines (vs. = 4) and male body posture “C” shaped (vs. elongate). This new species also closely resembles with O. columbiana but differs in higher body length (vs. L= 1288 μm), smaller “b” value (vs. b = 6.5), smaller stoma length (vs. SL= 23) and number of lateral lines (vs. = 4). O. gingeri sp. n. also resembles with O. andrassyi but differs in size of the body (vs. L= 1601 μm), larger “b” value (vs. b = 8.2), smaller “c” value (vs. c = 14.4), vulval opening (vs. V= 50.3%) and number of lateral lines (vs. = 6). This new species is capable to kill ginger shoot borer larva Conogethes punctiferalis and G. mellonella within 24–72 h under laboratory conditions. This opens a new hope of utilising Oscheius gingeri sp. n. as a biopesticide for management of the shoot borer and other insect pests of ginger.