Brahmina coriacea (Hope) is the most widely distributed and destructive species of white grubs having potential to inflict 40-50 per cent yield losses to potato in Himachal Pradesh. The efficacy of two local isolates of Beauveria brongniartii (KH I and KH II) was evaluated against grubs of B. coriacea by dip treatment and oral feeding methods. Against first and second instar grubs, KH I in dip treatment proved to be highly effective, whereas for third instar grubs, KH I through oral feeding showed higher virulence. The LC 50 values for first instar grubs for KH I and KH II were 2.55×10 5 conidia/ml and 2.80×10 5 conidia/ml in dip treatment, whereas in oral feeding method, the LC 50 values were 7.27×10 5 conidia/ml and 9.69×10 5 conidia/ml, respectively. Against second instar grubs, LC 50 values calculated were 2.91×10 5 conidia/ml and 3.98×10 5 conidia/ml for KH I and KH II in dip treatment, whereas corresponding values through oral feeding method were 5.36×10 5 conidia/ml and 8.82×10 5 conidia/ml. LC 50 values for third instar grubs were 4.47×10 5 conidia/ ml and 4.88×10 5 conidia/ml for KH I and KH II in dip treatment, whereas through oral feeding, LC 50 values were 3.03×10 5 conidia/ml and 5.14×10 5 conidia/ml for KH I and KH II, respectively.
White grubs are highly polyphagous and most destructive soil pests inflicting damage to a wide variety of crops. In India, more than 1000 species of white grubs are known of which over 40 species attack wide range of plants. White grubs are naturally infected by various entomopathogens which include fungi, bacteria and nematodes. Entomopathogenic fungi offer great potential and members of genera Beauveria and Metarhizium are widely used against white grubs. Several commercial products of entomopathogenic fungi like Bio Green, ORY-X, Grub X 10G, Betel, Biotrol FMA and Meta-Guard have been developed for the control of white grubs. In India, good control of white grubs in paddy, ginger and sugarcane has been achieved with different entomofungi. Among EPNs, Heterorhabditis bacteriophora is moderately effective against Popillia japonica and Rhizotrogus majalis. H. indica and H. bacteriophora are effective against potato white grubs in India. Paenibacillus popilliae cause milky disease in P. japonica grubs. The bacterium is pathogenic to Holotrichia consanguinea, H. serrata and Leucopholis lepidophora. In northwestern Himalaya, B. cereus is highly toxic to the grubs of H. seticollis and Anomala dimidiata.
Effect of climatic factors on population build-up of aphid complex of rapeseed-mustard viz. mustard aphid, Lipaphis erysimi (Kaltenbach), cabbage aphid, Brevicoryne brassicae (Linnaeus), and green peach aphid, Myzus persicae (Sulzer) and associated natural enemies (coccinellids, syrphids and a parasitoid, Diaeretiella rapae M’Intosh) was studied at Experimental Farm of CSK HPKV Palampur over a period of three years. Correlation coefficients indicated that the temperature favoured build-up of aphid population and their natural enemies while rainfall exerted negative impact. The population of coccinellids was negatively correlated with the population of L. erysimi and M. persicae while, positive correlation with B. brassicae was observed. On the other hand, population of syrphids was found to be positively correlated with aphid population. Predictive model using stepup regression analysis revealed that a weak relation in aphid population was attributed by weather parameters particularly minimum, maximum temperature and bright sunshine hours. Regression analysis revealed that 89 per cent variation in parasitization by D. rapae was attributed by minimum and maximum temperature, rainfall, relative humidity and bright sunshine hours.
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