HABITAT MANIPULATION IN HYBRID COTTON-10 AND EVALUATION OF SUBSEQUENT ARTHROPOD NATURAL ENEMIES ON INSECT PESTS

HABITAT MANIPULATION IN HYBRID COTTON-10 AND EVALUATION OF SUBSEQUENT ARTHROPOD NATURAL ENEMIES ON INSECT PESTS Name of Student Major Advisor Shri H. M. Patel Dr. D.N. Yadav All India Co-ordinated Research Project on Biological Control of Crop Pests and Weeds B. A. College of Agriculture Gujarat Agricultural University Anand Campus, Anand Impact of habitat manipulation on the arthropod natural enemies and subsequently on the insect pests of Cotton Hybrid-10 was studied at Anand Campus of Gujarat Agricultural University and Patelna Muvada, village of Sabarkantha district during 1999-2000. Habitat manipulation included maize, Zea mays L. and senna. Cassia angustifolia Vahl. at Anand whereas at Patelna Muvada, besides maize, Cassia occidentalis Linn, was included. The results revealed that maize and senna when interspersed with cotton, resulted in significant reduction in sucking pests viz., Aptiis gossypii, Amrasca biguttula biguttula, Bemisia tabaci, Thrips tabaci and bollworm, Earias vittella at Anand when compared with untreated control. Whereas it remained at par with insecticide treated plot. Maize and senna harboured ten and sixteen different species of arthropod natural enemies, respepctiyely which caused effective pest suppression in cotton. In presence of maize and senna, the cotton recorded thirty two species of natural enemies. The occurrence of Trichogramma chilonis in the eggs of Catopsilia pyranthe on senna was an important mortality factor in the £. vittella incidence. There was greater activity of Aleiodes {=Rogas) aligarhensis in the habitat manipulated plot as compared to insecticidal application. The females of Chrysoperla carnea were found to lay greater number of eggs and lived longer when fed on maize pollen and honey dew excretion by aphids on cotton leaves. Interestingly, C. carnea did not lay eggs when fed on cotton pollen alone. At Patelna Muvada, cotton grown with maize also proved effective in reducing sucking pests and bollworm E. vittella. As many as eight different species of arthropod natural enemies were found on maize. The cotton and Cassia occidentalis combination proved effective in reducing bollworm, E. vittella. A. aligarhensis also caused appreciable morjability in the larvae of E. vittella. The cotton yield data also revealed the differences amongst the different manipulation. The plot manipulated with maize and senna recorded 618 kg/ha higher yield than untreated control at Anand. The insecticide treated control plot recorded 2382 kg/ha. At Patelna Muvada, interspersing of maize with cotton (3:1) and (1:1) recorded 2769 and 2377 kg/ha yield as against 2036 kg/ha in untreated control. The yield in case of cotton and C. occidentalis combination was comparatively lesser (2253 kg/ha) than cotton and maize but at par with insecticide treated control (2554 kg/ha). There was an additional gain in terms of maize grain (1030 kg/ha) and fodder (2537 kg/ha) at Anand. At Patelna Muvada, the grain and fodder yield was 715 and 1840 kg/ha, respectively in cotton and maize combination (3:1), whereas it was 1947 and 4574 kg/ha in cotton and maize combination (1:1). Incremental Cost Benefit Ratio in cotton with maize and senna was higher (1:11.26) as compared to insecticidal treatment (1:6.45) at Anand. It was higher (1:15.39) in combination of cotton and maize (3:1) than in insecticide treated plot (1:4.31) at Patelna Muvada. It was 1:11.76 and 1:6.25 in cotton and C. occidentalis combination and cotton with maize (1:1), respectively. Additional host plants which harbour arthropod natural enemies need to be identified and test verified to enhance natural biological control in the main crop.