ABSTRACT:The study was carried out during 2010-11 at farmer fields and laboratory, College of Agriculture, Osmanabad District (Vasantrao Naik Marathwada Agricultural University (VNMKV), Parbhani), Maharashtra, India on the incidence of parasitoids of Melanagromyza obtusa (Malloch) infesting pigeonpea. Four hymenopteran parasitoids recorded were; the Eulophid parasitoid, the torymid Torymoides sp. (Walker), two ormyrids viz., Ormyrus orientalis (Walker) and Ormyrus sp. (Westwood). As per the literature available and reviewed, Torymoides sp. is the first ever record for new host association reported from M. obtusa maggots as an ecto-parasitoid. The natural larval parasitism of M. obtusa by Torymoides sp. ranged from 3.13 to 31.82 per cent. The parasitism was observed from 51 st SMW (3.13 per cent) which increased gradually and attained a peak on 6 th SMW with 31.82 per cent with a mean parasitism of 9.30 per cent over a period of 13 standard meteorological weeks. The new record of natural parasitism of pod fly by Torymoides sp. would add to the existing knowledge on the biological suppression of the pest.
Melanagromyza obtusa (Malloch) has been recorded for the first time on pigeonpea at Nagpur, India and named as 'tur pod fly'. It is a monophagous species and devours the developing seeds of pigeonpea crop. It was reported to infest 12 to 100% pods causing losses of 2.4-95.0% on seed or grain (=250000 tonnes by weight) and are estimated at US $ 256 million annually. Therefore, a field experiment was conducted at Research Farm, Agricultural Research Station, Badnapur (VNMKV), India during kharif 2015-16 to source some promising pigeonpea genotypes against M. obtusa. The present investigations revealed the population of M. obtusa on 20 genotypes ranged from 0.00-277.64 maggots per 100 pods; pod and grain damage were ranging from 0.00-89.75 and 0.00-82.02%. The highest M. obtusa population, pod and grain damage was recorded in BRG-2 (277.64 maggots and 101.26 pupae per 100 pods; and 89.75 and 82.02%). On the basis of pod damage a total of five, two, eight, four and one genotypes were categorized as highly tolerant, tolerant, moderately tolerant, susceptible and highly susceptible; for grain damage these were seven, seven, three, two and one, respectively. The maximum yield was recorded from BDN-2010-1 (22.33 q/ha), followed by V-127 (21.61 q/ha). However, Cajanus scarabaeoides showed no maggot and pupal population, pod and grain damage by M. obtusa indicating its virtue of genetic resistance and it can be used in breeding programmes to develop resistant cultivars for farmer’s welfare.
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