Phenology of Major Sucking Pests and Their Natural Enemies on Cotton in Relation to Meteorological Variables

A seasonal study was conducted from May to September to monitor the dynamics of sucking pests thrips, leafhoppers, and whiteflies and their natural enemies, including spiders, coccinellids, and Chrysoperla, in relation to weather parameters. Maximum temperatures ranged from 33.1°C to 45.6°C, minimum temperatures from 24.0°C to 32.7°C, and relative humidity varied between 25% and 69.6%, with intermittent rainfall primarily from July onwards. Results showed that thrips were the dominant pest during May and June, reaching densities of 15.22–22.68 per three leaves per plant, but declined sharply to 1.82–4.82 by August and 0.24–1.21 by September as humidity increased and rainfall occurred. Leafhoppers were initially low (0.48–3.94) in May–June but increased substantially under humid conditions in July–August, peaking at 13.4–17.46 per three leaves per plant, before declining to 2.06–8.16 in September. Whiteflies maintained moderate populations throughout the season, ranging from 0.08–5.72 in summer, peaking in August, and gradually declining by September. Natural enemies exhibited a delayed but positive response to pest abundance. Spiders increased from 0.22–0.96 per plant in May–June to 1.84–2.76 per plant in August, coccinellids from 0.2–0.82 to 0.72–1.27, and Chrysoperla from 0.11–0.83 to 0.32–0.87 per plant. These results demonstrate that temperature, relative humidity, and rainfall strongly influence pest population dynamics, with thrips thriving under hot, dry conditions, leafhoppers favored by high humidity, and whiteflies remaining resilient. The study highlights the importance of integrated pest management strategies that align with seasonal environmental conditions and predator-prey interactions to sustainably reduce pest pressure and conserve beneficial insects in summer crops.