Fruit flies of economic significance in India, with special reference to Bactrocera dorsalis (Hendel).
Abraham Verghese, Madhura H. S., Jayanthi P. D. K., Stonehouse J. M.
Author Affiliation: Indian Institute of Horticultural Research, Hessaraghatta Lake P.O., Bangalore 560 089, Karnataka, India.
: 317-324
Abstract : India has nearly 200 species of fruit flies, which is about 5% of the known tephritid fauna of the world. The subfamily Dacinae has the maximum number of economically important species. The tribe Dacini with the genus Bactrocera is of importance in India. From an economic point of view, B. dorsalis (Hendel), B. correcta (Bezzi), B. zonata (Saunders) and B. cucurbitae (Coquillett) are important. The first three species mainly attack fruit crops, while B. cucurbitae attacks different species of cucurbits. In an Indian context, B. dorsalis is a major fruit fly pest, especially on mango, affecting local and export markets. The crop loss due to B. dorsalis varies with season and region. In Bangalore, it was found that the loss to mango in an unsprayed situation varied from 2.5 to 59.0% depending on the variety. The cultivars Dushehari and Langra were least infested, while cultivars Banganpalli and Totapuri had a mean infestation of 46.0 and 59.0%, respectively. In guava it is reported that B. dorsalis causes between 5 and 70% crop loss. An assortment of management strategies has been evaluated in India. A study from northeast India by Makhmoor & Singh (1997) showed that hoeing once a day, once in three days and once in seven days resulted in 80, 70 and 43% pupal mortality, respectively, of B. dorsalis. Soil type also influenced pupal mortality, with maximum mortality occurring on clayey soil. The use of the parapheromone 'methyl eugenol' in traps is quite popular in India. Of the different traps evaluated, namely IIHR bottle trap, Steiner trap, McPhail trap, delta trap, Jackson sticky trap and open pan trap, the IIHR bottle trap attracted the most flies. Trapping has been found to be useful both for monitoring and management. Using extracts of Ocimum sanctum in traps is also in vogue, but is less efficient than methyl eugenol. Pre-harvest sprays using either dimethoate 0.06%, carbaryl 0.2% or deltamethrin 0.0028% are also recommended. At the Indian Institute of Horticultural Research an IPM package for the management of B. dorsalis on mango is recommended, which consists of orchard sanitation together with inter-tree ploughing and raking plus three applications of insecticidal sprays of the above-mentioned chemicals on the fruits. This has given between 76 and 100% control. A double-walled steel tank of 1 cubic metre with a thermostat was manufactured to test post-harvest disinfestations of mango using hot water. It was found that a postharvest hot-water treatment at 48°C for 60 to 75 minutes gave satisfactory results. A combination of pre- and post-harvest management gave 100% control of B. dorsalis. The aim of this paper is to highlight the research findings on B. dorsalis in India, based on work carried out at IIHR, Bangalore, and elsewhere in the country. The distribution, species complex and other wild hosts of the genus Bactrocera are discussed.