Studies on species composition and population dynamics of coccinellids
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Abstract
Investigations on species composition and population dynamics of coccinellids were
carried out during 2012-13 at MARS, University of Agricultural sciences, Dharwad. Survey
was carried out in three different ecosystems viz., agricultural, horticultural and organically
grown crops. A total of 18 different species were collected. The species were Coccinella
transversalis Fabricius, Micraspis discolor Fabricius complex, Brumoides
suturalis Fabricius, Cheilomenes sexmaculata Fabricius, Chilocorus melas Weise, Propylea
dissecta Mulsant, Rodolia fumida Mulsant, Coelophora bissellata Mulsant, Epilachna
vigicultntioctopunctata Fabricius, Telsimia bangalorensis Kapur, Harmonia
octomaculata Fabricius, Scymnus castaneus Sicard, Illeis cincta Fabricius, Scymnus
coccivora Ayyar, Illeis sp. (Bistigmosa group), Pseudaspidimerus flaviceps Walker,
Hippodamia variegata Goeze and Scymnus nubilus Mulsant. Parasitisation of predator, C.
sexmaculata grubs and pupae by encyrtid parasitoid, Homalolytes sp. caused 15-94 and 15-95
per cent parasitization, respectively.
During the cropping season, the activity of coccinellids and aphids was noticed from
29-33rd and 29-31st standard week in sorghum, respectively; In maize the activity of
coccinellids and aphids was noticed from 33-37th standard week, in cowpea the activity of
coccinellid predators and aphids was noticed from 46th - 5th standard week. In safflower the
activity of coccinellids and aphids was noticed from 48th - 51st and 47th to 51st standard weeks
respectively. In Lucerne the activity of predatory coccinellids was noticed during 27-28th, 31-
37th 40-43rd 51-4th standard weeks.
Toxicity of various insecticides to the adults of C. sexmaculata and H.variegata was
studied under laboratory condition. Fenvalerate (60%) and imidacloprid (63.33%) were found
to be relatively safer to C. sexmaculata and Thiomethaxam and fenvalerate were found to be
safer to H. variegata by causing 46.67 per cent mortality compared to other test insecticides.
Whereas, dimethoate, dichlorvos, monocrotophos, Oxydemeton-methyl, methyl parathion,
nimbicidine and malathoin were completely toxic with 100 per cent mortality to both the
coccinellid species.
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