Factors affecting progeny production and sex ratio of Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae)

Authors: Hougardy, Evelyne; Hogg, Brian

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2022
Publication Date: 11/2/2022
Citation: Hougardy, E.H., Hogg, B.N. 2022. Factors affecting progeny production and sex ratio of Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae). Insects. 13(11). Article 1010. https://doi.org/10.3390/insects13111010.
DOI: https://doi.org/10.3390/insects13111010

Interpretive Summary: To rear and release natural enemies of crop pests in large numbers, the conditions for producing natural enemies must be maximized. Many factors can influence the production of natural enemies. The production of female natural enemies is particularly important because females produce offspring. In a series of experiments, we studied the effects of several factors on production of a parasitic wasp that attacks the eggs of an invasive stinkbug pest of cole crops (i.e., cabbage, broccoli, kale, etc.). Production of females increased when eggs were exposed to female wasps for one day rather than two days. Total production of offspring dropped when females were older than 24 days old and was highest at higher temperatures (26.6 and 28.9 °C). Results show that production of this parasitic wasp can be maximized when eggs are exposed for only one day, using females that are less than 24 days old, at a temperature of around 26 °C.

Technical Abstract: Manipulating the factors that influence progeny production and sex ratio in parasitoids can help maximize production for quarantine bioassays and/or mass releases. In a series of experiments, we studied the effects of several factors on offspring production and sex ratio in the parasitoid Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae). Progeny production was influenced by maternal age and dropped when females were 24 or 28 d old and decreased on the second day of exposure. Overall, offspring sex ratio was highly variable in G. aetherium, and was affected by duration of exposure, with higher proportions of females emerging after one day of exposure than after two days but was unaffected by female density and female age/host deprivation. Both progeny production and sex ratio were affected by temperature during oviposition; progeny production was highest at 26.6 °C and proportions of females were highest at 28.9 °C. Results indicate that production of G.aetherium can be maximized at one day of exposure, using females that are less than 24 d old, at a temperature of around 26°C.