Biology and Management of Rice Earhead Bug, Leptocorisa oratorius, Fabricius (Hemiptera : Alydidae) in Rainfed Ecosystem of Uttara Kannada District
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Date
2011
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Publisher
UAS, Dharwad
Abstract
Studies on bioecology and management of rice earhead bug, Leptocorisa
oratorius, Fabricius (Hemiptera: Alydidae) were undertaken during kharif, 2010 in
rainfed ecosystem of Uttara Kannada district.
Uttara Kannada district represents three distinct rice ecosystems, namely;
’upghat’ drill sown paddy, ’upghat’ transplanted paddy and coastal transplanted
paddy. The roving survey taken up in these ecosystems revealed the two species
belonging to the genus Leptocorisa, viz., L. oratorius, and L. lepida. Assuming that all
rice earhead bugs were L. oratorius, it was confirmed by observing the characteristic
black ventrolateral spots on the abdominal segments of this species. Among the two
species L. oratorius was of high abundance and noticed in almost all places of
surveyed.
The highest incidence of rice earhead bug was recorded at reproductive stage
of crop during kharif season than rabi. The maximum population of 3.04 nymphs and
adults per hill was recorded, during October (kharif-2010) in Mundgod and least in
Sirsi (1.97/hill). Whereas, in rabi (2011) maximum population of 2.04 nymphs and
adults per hill was recorded during May in Mundgod and least in Kumta (1.08/hill).
The preadatory spiders, coccinellids, ground beetles, dragonflies, damselflies, bugs
and roberflies were recorded during both the seasons. Seven alternate hosts of rice
earhead bug were observed during survey which included Echinocloa crusagalli (L.),
Echinocloa colonum (Link.), Eleusina indica (L.) Gaertn, Digitaria sanguinalis (L.),
Cyperes rotundus (L.), Cyperes iria (L.) and Brachiria mutica (Stapf.).
Among the various botanicals, entomopathogenic fungi and synthetic
insecticides evaluated for the management of rice earhead bug, imidacloprid 17.8 SL
@ 0.25 ml/l was found very effective in reducing rice bug population and was at par
with thiamethoxam 25 WG @ 0.3 g/l and malathion 5D @ 20 kg/ha. Next best
treatments included azadirachtin 3000 ppm @ 3 ml/l and Acorus calamus aqueous
rhizome extract @ 10%.
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Keywords
Agricultural Entomology