BIOLOGY OF SPOTTED BOLLWORM, EARIAS VITTELLA (FAB.) ON OKRA

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1 Journal of Computer Science & Technology BIOLOGY OF SPOTTED BOLLWORM, EARIAS VITTELLA (FAB.) ON OKRA Nishi Sewak Department of Zoology, School of Entomology St John s College, Agra, India ABSTRACT: A life cycle study on Earias vittella (F.) conducted under the laboratory conditions, on Okra, revealed that the egg incubation, larval and pupal period ranged from.5 ± 0.5, 11.5 ± 1.08 and 8.0 ± 0.8 days. The female fecundity rate ranged from 199 ± 4. eggs in its life time. The pre-oviposition, oviposition and post-oviposition durations were 1.8 ± 0.78,.8 ± 0.79 and 4.5 ± 0.5 days, while the adult male and female longevities observed were about 4. ± 0.79 and 9.5 ± 1.08 days respectively. The total life-cycle completed between 8-7 days with an average mean value of.5 ±.4 under the prevailing laboratory conditions. Keywords: Biology, Earias vittella, Okra.. 1 INTRODUCTION Okra, Abelmoschus esculentus (L.) is a native of tropical or sub-tropical Africa. It has been grown in Mediterranean region as well as in the tropical and subtropical regions (Yawalkar, 199). In India okra is being cultivated around the year in Kharif, Rabi and Summer seasons. At the same time, Okra is an export-oriented crop in India as its fruits are exported to the neighbouring countries (Khan et al., 01). While on the other hand, the fruit and shoot borer, Earias vittella Fab. (Lepidoptera;Noctuidae) is a polyphagous and widely distributed pest infesting Okra. The larva bores into the tender terminal shoots in the vegetative stage also infesting the flower buds, flowers and young fruits in the fruit Mail: editor@globalresearch.co.in 6

2 Journal of Computer Science & Technology formation stage. The infested fruits present a deformed appearance and become unsuitable for consumption. The bored holes present on the fruits are seen plugged and excreta. Thus, resulting in the deterioration of the quality of the fruits. So, the present study was taken up on the biology of the pest during the months of March and April 014, to suggest suitable options for the management of the pest. MATERIALS AND METHOD Laboratory culture of the pest was established by collecting a large number of its larva from the field and reared on Okra. The weather conditions maintained in the laboratory were maximum temperature C and minimum temperature C and relative humidity (max.) and 14-4 (min.) per cent respectively. The adults that emerged were fed with 10% honey solution fortified with multivitamins and were allowed to lay eggs on Okra fruits and leaves kept in the rearing cage. Ten pairs of adults were transferred to fresh fruits and leaves for egg laying, every day fresh fruit and leaves were given to each pair after removing the old ones, so as to record the total fecundity. Observations were made on the period of pre-oviposition, oviposition, postoviposition, eggs, larva and pupa. However, the egg laying pattern and longevity of male and female were also studied. RESULTS AND DISCUSSION The eggs were laid singly (Plate 1) for over a period of.8 ± 0.79 days (Table 1), which were spherical, crown shaped and light bluish-green in colour. Each female deposited an average of 199 ± 4. eggs during her life time and the average incubation period was for about.5 ± 0.5 days respectively. Further, the post-oviposition period was about 4.5 ± 0.5 days. The average male and female adult longevity was about 4. ± 0.79 and 9.5 ± 1.08 days respectively. The average larval duration for I st, II nd, III rd, IV th and V th was 1.6 ± 0.5,.0 ± 0.00,.5 ±0.5,.5 ±0.5 and.0 ±0.00 respectively. Mail: editor@globalresearch.co.in 7

3 Journal of Computer Science & Technology After hatching the later instars bored and fed both into the Okra shoots as well as the fruits. The full-grown larvae are brownish white with brownish and milky white markings on the dorsal side of the body (Plate ). Pupation occurred in a dirty white boat-shaped cocoon (Plate ). The total larval and pupal period was for about 11.5 ± 1.08 and 8.0 ± 0.8 days respectively. The moths are medium sized with head and thorax pale brownish white, forewings pale white with a wedge shaped horizontal green band in the middle while the hindwings are silvery-creamy white in colour (Plate 4). The adult female after emergence took an average period of about 1.8 ± 0.78 days to lay the eggs. The observations (Table 1) are in concurrence with the findings of Naresh, et al., (004) and Bhat, et al., (005) respectively. Plate 1. Eggs on Okra fruit Plate. Larvae Plate. Pupae Plate. Adult Mail: editor@globalresearch.co.in 8

4 Journal of Computer Science & Technology Life stages of Earias vittella Table 1. Biology of Earias vittella on Okra during March-April 014 Stage Attribute (units) Days Average value ± SD Min. Max. Egg Incubation period (days) 4.5 ± 0.5 Larva Duration (days) I instar ± 0.5 II Instar.0 ± 0.00 III instar.5 ± 0.5 IV instar.5 ± 0.5 V instar.0± 0.00 Total ± 1.08 Pupa Duration (days) ± 0.8 Adult Duration (days) Pre-oviposition ± 0.78 Oviposition 4.8 ± 0.79 Post-oviposition ± 0.5 Longevity Female ± 1.08 Male 5 4. ± 0.79 Fecundity (Eggs/Female) ± 4. Total life-cycle ±.4 Values followed by mean are calculated by standard deviation Mail: editor@globalresearch.co.in 9

5 Journal of Computer Science & Technology 4 CONCLUSION The present investigation reveals the life-cycle of Earias vittella in the months of March and April, when the pest attack on the crop is very prevalent, causing severe damage to the crop, resulting direct loss in the yield of the crop. Thus, the present study which provides the complete information of the different stages and their durations in a generation, can be exploited to take necessary, effective and eco-friendly approaches towards the management of this notorious pest on Okra. References 1. Bhat, O.K.,Bhagat, K.C., Koul, V.K., and Rajinder, B. (005). Studies on the biology of Spotted bollworm Earias vittella (Fab.) on Okra. Annals of Plant Protection Sciences, 1 (1): Naresh, V., Roy K., Biswas, A.K. and Reza, M.W., (004). A note on the biology of the shoot and fruit borer, Earias vittella (Fab.) on Okra in West Bengal. Pest Management and Economic Zoology, 1 (1): Sahak, K.A. and H. Lyall, (01). Efficacy of chemical and plant products in management of Earias vittella Fab. On Okra. Annals of Plant Protection Sciences, 1(): Yawalkar, K.S. (199).Cultivation of Okra in vegetable crops of India, Ed. Agri. Horticultural Publishing house, Nagpur (M.S). pp Mail: editor@globalresearch.co.in 0