Leaf eating caterpillar Trilocha varians (Bombycidae: Lepidoptera) is one of the major pest of Ficus spp. (Naeem-Ullah et al., 2020) and well distributed in Nepal, India, Pakistan, Sri Lanka, Thailand, Taiwan, Java, Malaysia, Southern China, Japan, Philippines and Indonesia (Zolotuhin and Witt, 2009; Gurule, 2013; Chuenban et al., 2017). The major hosts of T. varians are Ficus religiosa, F. infectoria, F. elastica and F. bengalensis (Kedar et al., 2014). Other host plants are Artocarpus heterophyllus, A. communis, A. kamansi, F. nitida, F. septica, F. mclelandi and F. caraica (Navasero et al., 2013; Chu and Wang, 1993). The young larvae feed on leaves, twigs and tender shoots, due to their feeding the leaves appear transparent while the late instars cause complete defoliation of the plants. A review of literature revealed that this is the first severe incidence of T. varians feeding on F. microcarpa in Rajasthan. Earlier, T. varians infesting several species of Ficus, has been reported in Haryana, Punjab, parts of Maharashtra, Assam, Karnataka, Tamil Nadu (Kedar et al., 2014, Singh et al., 2017, Gurule and Nikam, 2013; Pathre et al., 2019; Subhasish and Tariang, 2018; Udayagiri, 1988; Rajavel and Shanthi, 2007). Various species of Ficus viz., F. benjamina, F. neuda, F. panda and F. microcarpa, etc. are planted to enhance the aesthetic value and for landscaping purpose, mainly planted alongside the roads, in many countries. However, maintaining healthy Ficus flora has great challenge to gardeners due to sudden outbreak of pests including defoliating insect pests. The present study has been conducted to evaluate the biological parameters of T. varians under laboratory conditions.

Study on biology of leaf eating caterpillar T. varians on Ficus was conducted during 2020 in the Laboratory of Department of Entomology, Agricultural Research Station, Mandor- Jodhpur, Rajasthan. The fourth and fifth instar larvae were collected from the infested Ficus trees planted in the University campus and brought to laboratory for culturing of the pest for further studies. The new and fresh Ficus leaves provided as feed and placed into containers containing T. varians larvae. On daily basis, left over leaves were changed and replenished with new leaves for larvae feeding. Final instars larvae transformed into pupae and emerged as adults. A pair of adults was placed into rearing cage for egg laying. The eggs were laid by female moth on jar wall and on Ficus leaves in the jar. Number of eggs was counted on daily basis and observations were recorded on their colour, size, shape and incubation period. Newly hatched larvae were released singly in petriplates for studying duration of each instar and pupal period. The pre-oviposition, oviposition and post-oviposition periods, fecundity and longevity were studied by keeping the paired moths in glass jars. Measurement of various stages viz., eggs, larval instars, pupae and adults were recorded with the help of digital caliper.

The maximum infestation (10-15%) of T. varians was observed from second fortnight of September to first fortnight of November. Early instar larvae feed in cluster on under surface of leaves resulting in white and papery patches on upper surface of leaves. Later instar larvae got dispersed and fed irregular portions from the leaf margins towards the midribs consuming all the leaves of a branch. When most of the leaves were eaten up, twigs died back and in extreme cases, the plants succumbed to death. Otherwise, the plants recovered and produced new flush. The biological parameters of T. varians were studied under laboratory conditions. The results indicated that adult female laid 163.00± 22.63 eggs in long rows touching each other and round flat in shape. The freshly laid eggs were pale yellow in colour while before hatching changed into black colour. These findings are in line with Rajavel and Shanthi (2007) and Daimon et al. (2012). The incubation period of eggs was 4.30± 0.67 days (Table 1). Similarly, Singh and Brar (2016) also observed that eggs hatched within 3-8 days. Egg width and thickness were measured 0.82± 0.18 and 0.49± 0.11 mm, respectively.

There were five larval instars and newly hatched larvae were brown in colour. After 24 hr, the colour of larvae changed to greyish white and remained same in colour up to fourth instar. The fifth instar larvae were dull brown with greyish bands. A caudal horn was present on 8^th abdominal segment of each larva. Similar findings were recorded by Daimon et al. (2012) and Singh and Brar (2016). Total larval duration was 18.30± 2.00 days. The body length of 1^st, 2^nd, 3^rd, 4^th and 5^th larval instars was 2.45± 0.60, 4.63± 0.73, 13.30± 2.36, 16.70± 3.43 and 30.60± 4.01 mm, respectively (Table 2). The length and width of cocoon were 9.82± 1.66 and 4.96± 0.56, respectively. The male pupa had an average length of 7.99± 0.91 and width of 2.86± 0.27 mm while the female pupa had length of 9.10± 1.29 and width of 3.83± 0.45 mm, respectively. Pupation took place in boat shaped silken cocoon. The colour of newly pupated larva was whitish yellow and changed into dark brown prior to adult emergence.

The present findings are in line with Rajavel and Shanthi (2007) and Daimon et al. (2012). Pupal stage lasted for 11.70± 1.57 days (Table 1). The head, thorax and abdomen of adults were dark reddish brown. The forewings were pale reddish brown having curved waved line. The hind wings were greyish with reddish brown outer margins. Our findings are in line with the findings of Singh and Brar (2016). Body length and wing span of male were 7.22± 0.54 and 15.00± 1.76, respectively while 8.88± 0.65 mm and 23.00± 1.94 mm, respectively in the female. The female was bigger in size than male. The female adult lived long as compared to male. Total life cycle of male and female was 35.50± 2.95 and 39.30± 3.97 days, respectively (Table 1). Jia and Jinxin, 1997 reported that the egg, larva, pupa and adult stages lasted for 4-8, 11-15, 3-17 and 5-16 days, respectively. The sex could be determined based on the presence and absence of a suture on the ninth abdominal segment in female and male, respectively.

n=10

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