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Subject: Agricultural Entomology × End date: 2019 × Start date: 2018 × Type: Thesis ×
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    ThesisItemOpen Access
    Bioecology and development of IPM module against fruit flies in cucurbits
    (2019-09) Mudoi, Abhilisa; Saikia, Dilip Kumar
    Fruit flies are the excellent candidates for studies of biodiversity, adaptability in changing climatic conditions and invasion to new areas because of their polyphagous nature, high reproductive potential, wide range of distribution and great economic importance as pests. Therefore, an extensive elaboration of fruit flies was carried out in five different districts under Upper, Central and Lower Brahmaputra Valley Zones of Assam to know the prevalence and diversity pattern of different fruit fly species of cucurbits. Five species of fruit flies viz., Bactrocera cucurbitae Coquillett, B. tau Walker, B. dorsalis Hendel, along with two new species viz., B. scutellaris Bezzi and Dacus longicornis Wiedemann were recorded from different districts of Assam. Out of the five districts, maximum number of 2492 individuals were observed to be trapped in cue lure in Darrang district. The species diversity index (1.285) and richness indices (0.393) of fruit fly was found to be highest in Michajan village of Sibsagar district, whereas the lowest species diversity index, (0.656) was in Dhepor village of Sibsagar district but the lowest richness indices (0.132) was observed in Khataniapara village of Darrang district. In respect of distribution pattern, the fruit flies had clumped distribution in all the five different districts under the present investigation. The morphometric parameters of fruit flies showed that the mean body length was the highest (11.846 ± 0.027mm) in female D. longicornis and lowest (5.631±0.053mm) in male of B. cucurbitae. In general, adult males were short-lived as compared to females, however, the adult longevity of female fruit fly in different cucurbits varied from 63.91 ± 1.16, 60.37±0.41, 49.82±0.50mm in respect of B. dorsalis, B. tau and B. cucurbitae against bitter gourd, bitter gourd and bottle gourd, respectively. Morphometrics of immatures stages revealed that the egg (1.26±0.02 × 0.43±0.02), larval (9.59±0.07 × 1.85±0.01) and pupal (5.82±0.01 × 2.46±0.02) size was highest in B. tau followed by B. cucurbitae with 0.88±0.01 × 0.18±0.01, 8.07±0.07 × 1.12±0.01, 5.21±0.03 × 2.22±0.02mm, respectively. It is imperative to obtain a baseline data on the seasonal occurrence pattern of fruit flies and the influence of abiotic factors on their activities in a particular ecosystem. Therefore, an experiment was carried out under field conditions at the Horticultural orchard, Department of Horticulture, Assam Agricultural University, Jorhat during 2017-18 and 2018-19 to find out a suitable eco-friendly management module against fruit flies of bitter gourd. Insect pests encountered with the crop revealed altogether seven species under three orders with four families viz., B. cucurbitae, B. dorsalis, B. tau, Aphis gossypii Glover, Epilachna vigintioctopunctata F., Aulacophora foevicollis Lucas and Monolepta signata Olivier which were registered as major pests of bitter gourd. Among the natural enemies, a total of sixteen species belonging to three orders and seven families were recorded. Twelve different pollinator species were also recorded during the study period associated with the crop. The seasonal incidence of fruit flies indicated a maximum of 189.90 and 179.60 number of fruit flies were trapped during April, 2017-18 and 2018-19, respectively. Among the different insect pests, the relative abundance of fruit fly, B. dorsalis was the highest with 73.65 in 2017-18 and 69.41 per cent in 2018-19 and the lowest was in case of A. foevicolis and A. gossypii, respectively with 1.69 and 2.65 per cent during the respective years. The correlation study with population build up of fruit fly showed a significant positive correlation with maximum and minimum temperature. As regards to fruit fly management strategies, module IV comprised of good agricultural practices, installation of cue lure @ 10/ ha, destruction of damage fruits, spray of neem based insecticides and spray of spinosad 45 SC @ 0.3 ml/L was found to be the best with 0.90 damaged fruits / m2, followed by module III (2.28 damaged fruits / m2) and module II (3.23 damaged fruits / m2). Similarly, module IV (1.36/ m2) and module III (2.46/ m2) was also found to be superior in suppressing the population of phytophagous beetle, E. vigintioctopunctata. In case of M. signata and A. foevocolis, module III (2.30,2.25) and module IV (1.00,1.18) was almost at par in reducing the population. The maximum yield of 97.43 q/ha with a benefit cost ratio of 2.26 was recorded in module IV, followed by next effective module III (83.93 q/ha) with a benefit cost ratio of 2.08. However, the cue lure barrix fly trap showed maximum efficacy related to trap index of 28.76 and the lowest was recorded in molasses trap with trap index of 21.79.