Stage-Dependent Predation by Scymnus (Scymnus) folchinii Against Myzus persicae: Functional Response and First-Instar Prey Sharing
1
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling 712100, China
2
Institute of Entomology, Guizhou University, Guiyang 550025, China
*
Author to whom correspondence should be addressed.
Insects 2026, 17(6), 629; https://doi.org/10.3390/insects17060629
Submission received: 6 May 2026
/
Revised: 4 June 2026
/
Accepted: 8 June 2026
/
Published: 15 June 2026
(This article belongs to the Section Insect Pest and Vector Management)
Simple Summary
Small ladybird beetles of the genus Scymnus occur in many crop systems, but their feeding capacity is less often measured than that of larger aphid-feeding ladybirds. We examined how larvae and adults of Scymnus (Scymnus) folchinii fed on third-instar green peach aphids on chili pepper seedlings. Larvae and adults handled aphids differently. Larvae showed feeding behavior consistent with extra-oral digestion, whereas adults chewed aphids directly. In a single-prey group-feeding assay, first-instar larvae often fed on the same aphid at the same time. Aphid consumption increased from early larvae to late larvae and adults. Functional-response models most often fitted the data as Type II-like responses, but the response type was not clearly resolved for every stage and exposure period. Late larvae and adults removed aphids most rapidly in the seedling arena. These laboratory results support further testing of this small ladybird under field conditions.
Abstract
Small scymnine coccinellids, including many Scymnus species, are common aphid predators, but stage-specific feeding data are still limited for many species. We investigated feeding behavior, first-instar prey sharing, stage-specific consumption, and functional responses of Scymnus (Scymnus) folchinii (Canepari) on third-instar Myzus persicae nymphs on chili pepper seedlings. Larvae showed feeding behavior consistent with extra-oral digestion, whereas adults consumed aphids by direct mastication. In the single-prey first-instar assay, prey sharing occurred in all 15 arenas; the period during which two or more larvae fed on the same aphid lasted a median of 31.0 min and accounted for 84.8% of the observed feeding period. Aphid consumption varied with predator stage, exposure time, and initial aphid density. At the highest tested density of 16 aphids, third- and fourth-instar larvae and adults left few aphids alive after 24 h in the seedling micro-arena. Logistic regression diagnosed Type II responses only for adults at 1 h, whereas AIC-based model comparison selected Rogers’ Type II in 15 of 18 stage-by-duration combinations. Short exposures indicated higher attack rates and shorter handling times in fourth instars and adults, whereas longer exposures were affected by prey depletion and satiation. These results show clear stage dependence in aphid consumption by S. folchinii and justify further testing on larger plants and under field conditions.
