DENSITY AND DIVERSITY OF PREDACEOUS COCCINELLIDAE IN VARIOUS CROPPING SYSTEMS
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Date
2019-07-30
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UNIVERSITY OF AGRICULTURAL SCIENCES, RAICHUR – 584 104
Abstract
The present investigation on the density and diversity of predaceous Coccinellidae
was carried out on the three agro-climatic zones of North East Karnataka during 2018-19.
Crops such as pulses, inorganic paddy, organic paddy, maize, cotton and sugarcane, citrus
and guava have been surveyed at different stages and seasons to see the predatory
coccinellid composition along with its density. During the survey, 36 species of predatory
coccinellids were recorded across the seven ecosystems. Species composition was highest
in guava, recording 17 species, followed by cotton and maize (11 and 10 species,
respectively). Pulse ecosystem recorded a lowest species composition of five. In the entire
ecosystem Cheilomenes sexmaculata (Fabricius) was the common and dominant species
recording 2575 specimens, however, in citrus, Serangium serratum Poorani and Stethorus
species were dominant. The species S. serratum was recorded for the first time from the
citrus, feeding on citrus psyllid, Diaphorina citri Kuwayama, which is also a new host
species recorded for this predator. Results with respect to the diversity analysis indicated
that, diversity, effective number of species, dominance and richness were highest in
guava (H’ = 1.80, ENS = 6.06, D = 0.79 and DMg=2.58, respectively) and lowest diversity
and dominance of 0.30 and 0.13, respectively was recorded in pulse and maize. Further,
lowest ENS and richness was recorded in pulses and sugarcane (1.36 and 0.60,
respectively). The evenness was highest recorded in inorganic paddy and lowest in pulses
(J = 0.67 and 0.20, respectively). Studies on prey-predator relationship with respect to
population density reveled, a significant positive relationship between the population
buildup of both prey and predator. The regression values recorded an average of R2 =
0.5016, in other words, the variation in the prey population across the selected crops was
influenced by 50.16 per cent on predator population.
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