Hira Kaji Manandhar

Natural occurrence and distribution of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in Nepal.

A survey of entomopathogenic nematodes (EPN) was conducted for the first time in Nepal during June-December 2007. EPN were recovered from 29 of the 276 soil samples (10.50%). Molecular and morphological tools were used to identify the isolates. Among 29 positive samples, seven samples (24.14%) yielded heterorhabditids (Heterorhabditis indica) and 22 samples (75.86%) contained steinernematids. Among steinernematids, seven isolates were identified as one of four described species (Steinernema abbasi, S. cholashanense, S. feltiae and S. siamkayai) whereas 15 isolates did not fit any description. H. indica was recovered from diverse habitats. Distribution of steinernematids has followed ecological niches and localized areas.

Steinernema lamjungense n. sp. (Rhabditida: Steinernematidae), a new species of entomopathogenic nematode from Lamjung district, Nepal

A new species of entomopathogenic nematode, Steinernema lamjungense n. sp., was recovered from soil samples collected from Tarku, Lamjung district of Nepal, during a survey in 2007. The analysis of ITS-rDNA sequence placed S. lamjungense n. sp. in the arenarium-glaseri-karii-longicaudum group. The nematode can be separated from other described species of the group by morphological and morphometric characteristics of different stages and by characterisations and phylogeny of DNA sequences of the D2D3 domain of the LSU or ITS regions of rDNA. For infective juveniles, the new species can be recognised by medium-long body length of 832 (690-950) μ m, pharynx length of 127 (110-142) μ m, H% = 61 (55-69) and E% = 79 (69-97). The lateral field pattern is 2, 6, 7, 8, 3, 2. The males have well curved, yellowish-brown spicules with a prominent velum. The spicule terminus is blunt with a longitudinal ventral notch. Spicule length is 87 (81-94) μ m and gubernaculum length is 57 (50-66) μ m in the first generation males. A tail mucron is absent in first but present in second generation males. First generation males have a lateral field with a single ridge. A post-anal swelling is not developed in first generation females but is well developed in second generation females. Three other isolates of the same species were recovered from the neighbourhood of the type locality and yet another isolate was collected from Swarketari, Syangja district.

Steinernema everestense n. sp. (Rhabditida: Steinernematidae), a new species of entomopathogenic nematode from Pakhribas, Dhankuta, Nepal

A new species of entomopathogenic nematode, Steinernema everestense n. sp., was recovered from soil samples collected from Pakhribas, Dhankuta district of Nepal, during a survey in 2007. The analysis of ITS-rDNA and D2D3 LSU sequences placed S. everestense n. sp. in the feltiae-kraussei-oregonense group. The nematode can be separated from other described species of Steinernema by morphological and morphometric characteristics and by characterisations and phylogeny inferred from DNA sequences of the D2D3 LSU or ITS regions of rDNA. For infective juveniles, the new species can be recognised by the body length of 775 (705-838) μm, pharynx 119 (110-130) μm long, H% = 61 (47-68) and E% = 78 (60-89). The lateral field pattern is 2, 8, 6, 4, 3. The males have well curved, brownish-yellow spicules with a prominent but short velum, gubernaculum plump, boat-shaped to almost straight in lateral view, cuneus long, needle-shaped, corpus with two wings in ventral view. Spicule and gubernaculum length of the first generation males is 79 (65-87) μm and 50 (39-57) μm, respectively. A tail mucron is present in both male generations. Genital papillae total 23 or 25, comprising 11 or 12 pairs and a single midventral papilla. Specimens with 23 genital papillae have eight precloacal pairs (seven pairs subventral and one pair lateral), two pairs subterminal and one pair subdorsal. The most posterior two pairs are consistently located near the tail tip. The specimens with 25 genital papillae have an extra adcloacal pair of papillae and the anteriormost two pairs are close together. The vulva is slightly protruding, mostly with equal lips, and low epiptygmata. A post-anal swelling is developed in most first and all second generation females.