Field Bunds Planted with Sesame Conserve the Predatory Mirid Bug Cyrtorhinus lividipennis and Suppress Piercing-Sucking Rice Pests: Evidence from a Two-Year Field and Molecular Gut Content Analysis

Habitat management using flowering plants on rice bunds and field ridges surrounding rice paddies can enhance conservation biological control by supporting beneficial predatory insects. However, multi-year field evidence for sesame (Sesamum indicum) when deployed as these bund-side flowering strips, and there is no molecular gut-content confirmation that the key predatory mirid bug Cyrtorhinus lividipennis preys upon rice planthoppers pests under field conditions. Over a two-year field experiment, we compared rice paddies with sesame-planted bunds against control paddies without bunds. We surveyed major piercing-sucking pests (brown planthoppers Nilaparvata lugens, white-backed planthoppers Sogatella furcifera, leafhoppers, and thrips) and their primary predator C. lividipennis throughout different rice phenological growth stages. PCR-based laboratory digestion assays were used to quantify the detectability of N. lugens DNA in the gut of laboratory-reared and field-collected C. lividipennis. Sesame-planted bunds significantly increased natural-enemy abundance (C. lividipennis) and reduced planthoppers, leafhopper, and thrips densities. Treatment effects varied by rice stage, with suppression mainly occurring from booting/heading to grain filling and no significant differences at tillering, and effects at maturity were weak. In the laboratory, N. lugens DNA detection declined from 68.75% at 0 h to 0% at 16 h after feeding. In the field, 37.5% of C. lividipennis from sesame-bund paddies tested positive for N. lugens DNA. These findings provide field and molecular evidence that sesame-planted bunds conserve C. lividipennis and contribute to suppression of piercing-sucking rice pests, supporting their use as an auxiliary habitat-management tactic in rice integrated pest management.