Ecological Intensification of Watermelon Production through Habitat Manipulation for Sustainable Arthropod Pest Management

Abstract

Ecological intensification through habitat manipulation has emerged as a sustainable strategy for reducing pesticide dependence while enhancing ecosystem services in agricultural production systems. The present study evaluated the influence of legume-based habitat manipulation on arthropod pest suppression, the conservation of beneficial arthropods, pollinator abundance, fruit yield and economic returns in watermelon (Citrullus lanatus L.). A field experiment was conducted during the kharif 2021 season at Namakkal, Tamil Nadu, India, using a randomised block design comprising five treatments, including cluster bean- and cowpea-based intercropping systems, with sole watermelon as the control. Habitat manipulation significantly reduced the populations of major insect pests compared with the sole crop. The cluster bean intercropping system (2:1 row ratio) recorded the lowest populations of aphids (6.48 insects per three leaves), thrips (2.35 per flower), whiteflies (3.82 per three leaves), leafhoppers (2.46 per three leaves), spider mites (4.28 per leaf) and fruit fly infestation (6.84%) compared with sole watermelon. The same treatment also supported the highest abundance of natural enemies (12.86 predators per plant) and pollinators (24.42 bee visits per 10 min), resulting in greater arthropod diversity (Shannon index: 2.74). Improved ecosystem services significantly enhanced fruit production, with the highest marketable yield (32.46 t ha⁻¹) and benefit–cost ratio (4.45) recorded under cluster bean intercropping at a 2:1 row ratio. The results demonstrate that habitat diversification through flowering legume companion crops promotes natural pest regulation, conserves beneficial arthropods, enhances pollination services and improves crop productivity and profitability. Habitat manipulation can, therefore, be integrated as an environmentally sound and economically viable component of sustainable integrated pest management programmes for watermelon cultivation in tropical agroecosystems.