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Impact of Non-Floral Sugar Sources and Feeding Protocols on the Longevity, Reproduction, and Parasitism of Mastrus ridens (Hymenoptera: Ichneumonidae)
Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago 7820436, Chile
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Insects 2026, 17(7), 693; https://doi.org/10.3390/insects17070693
Submission received: 31 May 2026
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Revised: 28 June 2026
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Accepted: 30 June 2026
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Published: 3 July 2026
(This article belongs to the Section Insect Pest and Vector Management)
Simple Summary
Conserving natural enemies in the field requires understanding their food requirements, in particularly, sugar sources for their maintenance and activity. In this study, we investigated the effects of non-floral sugar sources on Mastrus ridens, a beneficial wasp that attacks codling moth caterpillars. In the laboratory, we exposed wasps to the extrafloral nectar of broad beans, the sugary secretion (honeydew) of several sap-feeding insects, and positive (honey) and negative (no sugar) controls. We also tested the effects of a short 24 h exposure to honey. Our results revealed that not all sugar sources were equally beneficial for the wasps. Broad bean extrafloral nectar was better than mealybug honeydew because the wasps reproduced as much as with honey and increased their attack on the pest caterpillars by up to 3.5 times compared to no sugar control. Honeydew effects were variable among males, likely due to differences in composition and mode of presentation. Wasps exposed to honey for a short period performed poorly. Our findings provide valuable information for the use of this natural enemy and underscore the importance of having high-quality, accessible sugar resources in the field to enhance its impact. This will help in designing effective biodiversity-rich orchards with fewer chemical sprays.
Abstract
Successful conservation biological control programs require a good understanding the nutritional ecology of natural enemies to maximize their field efficacy. This study evaluated the effects of non-floral sugar sources on fitness parameters of Mastrus ridens, a specialized parasitoid of the codling moth. In the laboratory, we compared the longevity, parasitism, and reproduction of adult parasitoids exposed to different sugar sources, including Vicia faba extrafloral nectar, honeydew from several hemipteran species, diluted honey (positive control), and no-sugar controls. We also tested the effects of exposing parasitoids to honey for only 24 h. The results showed that sugar availability and source type significantly affected parasitoid performance. Extrafloral nectar was better than mealybug honeydew, with female offspring numbers similar to those exposed to honey, and increased the number of parasitized host larvae by up to 3.5-fold compared to no-sugar conditions. The effects of honeydew effects on male longevity were variable, possibly explained by its composition, and the mode of presentation. Parasitoids with a short exposure to high-quality sugar performed poorly. Our findings indicate that successful conservation and augmentative biological control programs using this species require field provision of high-quality, accessible sugar resources.
