PRAMOD KATTIMRUTHYUNJAYA, H.M.2017-06-232017-06-232012-06-30http://krishikosh.egranth.ac.in/handle/1/5810023088Studies undertaken at College of Agriculture and Main Agricultural Research Station, Raichur during 2011-12 on Bio - Ecology and crop loss estimation of Phenacoccus solenopsis (Homoptera: Pseudococcidae) Tinsley on sunflower (Helianthus annuus L.). Survey made in different sunflower growing areas of Raichur, Koppal and Bellary districts revealed the presence of only one species of mealy bug i.e Phenacoccus solenopsis. The population of mealy bug has increased gradually from October onwards and highest peak population was recorded from January onwards. The highest grade of mealy bug was in Raichur (1.56), Bellary (0.93) and Koppal (0.83) districts. Per cent infestation in field ranged from 7 to 27.50 per cent in three districts. The severe infestation was observed in Raichur district i.e in Lingasugur 27.50 per cent in February. The two parasitoids i,e., Aenasius bambawalei and Promuscidea unfasciativentris were recorded on the mealy bug. Among them A. bambawalei was predominant. The peak activity of the parasitoids was observed mainly from December to March. More than twelve alternate hosts have been recorded. Mainly Abuliton indicum, Seda cordifolia and Parthenum hysterophorous were major weed hosts of mealy bug for its colonizing. Studies on the life cycle of P. solenopsis on sunflower indicated that the female exhibited three nymphal instars without any pupal stage, while the male had three nymphal instars and a pupal stage. The total nymphal period was 23.98 ± 1.71 in male and 16.92 ± 1.19 in female, respectively. Incubation period of egg was very short (50.05 to 60 minutes). Parthenogenetic mode of reproduction was observed in P. solenopsis on sunflower. Fecundity of female mealy bug on sunflower was 497.66 ± 83.50 nymphs per female. Damage potential of P. solenopsis on sunflower by artificially infesting the plants with known numbers of mealy bugs indicated that mealy bugs population varied between 19.67 to 60 mealy bugs/plant at 25 days DAS. Yield varied between from 10.55 to 12.68 q/ha. However, plants infested at 45 DAS recorded seed yield of 10.33 to 13.84 q/ha. Therefore, late infestation did not show any significant reduction in the yield.ennullThesis