1. Effects of Temperature and Extraguild Prey Density on Intraguild Predation of Coccinella septempunctata and Harmonia axyridis.
- Author
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Wen, Xia and Gao, Guizhen
- Subjects
HARMONIA axyridis ,SEVEN-spotted ladybug ,INSECT pests ,WALNUT ,BIOLOGICAL pest control agents ,LADYBUGS - Abstract
Simple Summary: Chromaphis juglandicola is a serious insect pest of walnut trees. Harmonia axyridis and Coccinella septempunctata are ladybird species that are important predators of C. juglandicola. This study aimed to determine the effects of extraguild prey density and temperature on intraguild predation (IGP) between two ladybird species. The results showed that IGP increased with increasing temperature (15–35 °C) and decreasing extraguild prey density. The number of extraguild prey consumed by C. septempunctata or H. axyridis increased with increasing temperature. These results provide a scientific basis for the rational use of H. axyridis and C. septempunctata to control small walnut aphids. The ladybirds Coccinella septempunctata and Harmonia axyridis are important biocontrol agents for the small walnut aphid Chromaphis juglandicola, a key walnut pest. C. juglandicola outbreaks occur in walnut orchards, and walnut yields have declined. Intraguild predation (IGP) is prevalent among natural enemies that coexist in shared habitats and prey upon the same extraguild prey. We designed laboratory experiments to evaluate the potential for IGP between these two ladybirds at different temperatures and extraguild (EG) prey densities, and the ability of IGP to control EG prey under different conditions. We measured IGP rates in first instar larvae, female adults, and male adults (both starved for 24 h) in the vulnerable immature life stages of two ladybird eggs. Intraguild (IG) prey (H. axyridis eggs or C. septempunctata eggs) and EG prey (C. juglandicola) consumption were tallied after 24 h. Temperature and EG prey density influenced IGP rates, with temperature contributing the most to the variance. IGP increased with increasing temperature (15–35 °C), with both factors interactively influencing the EG prey consumption rate and exhibiting highly significant effects. EG prey consumption increased with temperature and density. This research provides theoretical support for the rational use of H. axyridis and C. septempunctata in the joint biological control of C. juglandicola [ABSTRACT FROM AUTHOR]
- Published
- 2025
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