Relationship between sucking pests (Amrasca biguttula biguttula, Aphis gossypii) and their predators (Cheilomenes sexmaculata, Chrysoperla carnea) on cotton cultivars
The abundance of sucking pests, viz, jassids,Amrasca biguttula biguttula Ishida and aphids, Aphis gossypii Glover and their native predators, viz, Cheilomenes sexmaculata (Fabricius) and Chrysoperla carnea (Steph.), on nine hybrids (NHH 44, PKV HY2, Kirti, JKHy1, H4, H6, H8, Savita and HH2) and four varieties (CNH 36, LRK 516, LRA 5166 and Supriya) of cotton was studied under rainfed conditions of Maharashtra. In general, hybrids harboured more number of jassids (4.85/plant) and aphids (47.56%) as compared to varieties i.e., 4.22/plant and 38.88%, respectively. Predators were almost four times higher on hybrids (2.4 no./plant) than on varieties (0.55 no./plant). Among hybrids, NHH 44 and PKV Hy 2 were consistently tolerant and H4 was highly susceptible to both the aphids and jassids. Differential reaction of cultivars to jassids and aphids was also observed. LRA 5166 exhibited differential response to jassid oviposition and feeding. Varying nature of associations of jassids and aphids to their predators were manifested by cultivars. While associations of jassids and predators were significantly positive on Kirti (0.93), H6 (0.86) and Savita (0.86), it was negative on PKV Hy 2 (−0.66). The only significant aphid-predator association was negative in relation to CNH 36 (− 0.69). This suggests that the compatibility of natural enemies and sucking pests would facilitate developing new varieties and pest management models, and modify thresholds.