POPULATION DYNAMICS, EXTENT OF DAMAGE AND ESTIMATION OF LOSSES CAUSED BY THE INVASIVE SOUTH AMERICAN TOMATO MOTH, Tuta absoluta (POVOLNY) (LEPIDOPTERA: GELECHIIDAE) ON SOLANACEOUS CROPS WITH SPECIAL REFERENCE TO TOMATO

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Date
2016
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
The present investigation entitled “Population dynamics, extent of damage and estimation of losses caused by the invasive South American tomato moth, Tuta absoluta (Povolny) (Lepidoptera: Gelechiidae) on Solanaceous crops with special reference to tomato” was conducted at the department of Entomology and experimental area of Department of Vegetable Science, Research cum Instructional Farm, IGKV, Raipur, (C.G.) during 2015-16. The invasive South American tomato moth, Tuta absoluta (Povolny) entered India a couple of year back and its presence was noticed in 2014 in Chhattisgarh. The seasonal activity of T. absoluta was monitored on Solanaceous crops like tomato, brinjal, chilli and potato crop during the period of present study from 13th August to 18th March during 2015-16. The month of February and March was identified as the peak activity period for T. absoluta on Solanaceous crops and was most active on tomato crop where its damage in form of broad mines was noticed on all aerial plant parts such as leaves, stem, bud flower and fruits. Least damage was observed on chilli crop. Studies on life cycle revealed that eggs were laid singly and the neonate larvae bore into the leaf tissue and fed on the mesophyll causing irregular broad mines. Four larval instars were recorded inside the mines which was confirmed by observing the molted head capsule. The mean length of the larvae at 1st, 2nd, 3rd and 4th instar was 1.8±0.04mm, 3.8±0.01mm, 4.76±0.02mm and 6.5±0.03mm respectively. Total larval period comprised of 12.41 days. Pupation took place inside mines which lasted for 9.3 days. Total life cycle was completed in 37.21 days. The length and wing span of the adult male and female were 4.10±0.02 mm, 4.68±0.01mm, 8.48±0. 01 mm and 8.93±0.03 mm respectively. The longevity of the female was more than males which was recorded as 10 days and 7 days respectively. Host preference studies based on various plant parts of Solanaceous crops conducted in the laboratory based on free choice test revealed that the larvae of T. absoluta preferred tomato leaves most followed by brinjal leaf and tomato fruit. Chilli was least preferred. A significant negative correlation (-0.537) was observed between peak population and morning relative humidity at 1% level of significant. Other weather factors were non- significant in tomato crop. Regarding natural enemies, parasitic wasp, Nesidiocoris spp., Neochrysocoris spp. and ground beetle were observed as major natural enemies of T. absoluta, however, their population was very low in the field. In the estimation of losses caused by T. absoluta, damage to fruits was only seen in tomato crops. Highest fruit damage percent 1.03 was recorded during 6th picking which was done in second week of February and apart from this some fruit damage was observed during 12th picking in fourth week of March. Although, very low percent of damage was recorded in the present studies in comparison to that recorded in some states in India, as per literature, the pest may become a major threat to Solanaceous crops in future.
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99 p.
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