|RAMUALDE, NATHALIE - European Biological Control Laboratory (EBCL)|
|MASPERO, MATTEO - European Biological Control Laboratory (EBCL)|
Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2021
Publication Date: 6/9/2021
Citation: Wang, X., Ramualde, N., Aparicio, E.M., Maspero, M., Duan, J.J., Smith, L. 2021. Optimal conditions for diapause survival of Aprostocetus fukutai, an egg parasitoid for biological control of Anoplophora chinensis. Insects. 12(6). https://doi.org/10.3390/insects12060535.
Interpretive Summary: The citrus longhorned beetle (CLB), a native of East Asia, is a high-risk invasive pest of hardwoods. Although no population has yet established in North America, CLB is frequently intercepted within live plants shipped to the U.S. To proactively develop a biological control program for this invasive pest, we evaluated a parasitic wasp that attacks CLB eggs and determined optimal conditions for wasp survival. Our results suggest that high humidity and mild winter temperatures are suitable conditions for this natural enemy that will be helpful for rearing this natural enemy for biological control of CLB.
Technical Abstract: Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora chinensis, a high-risk invasive pest of hardwood trees. The parasitoid overwinters as diapausing mature larva within the host egg and emerges in early summer in synchrony with the egg-laying peak of A. chinensis. This study investigated the parasitoid’s diapause survival in parasitized host eggs that were either naturally laid on potted trees under semi-natural conditions in southern France or removed from wood and held at four different humidities (44, 75, 85–93 and 100% RH) at 11°C or four different temperature regimes (2, 5, 10 and 12.5°C) at 100% RH in the laboratory. The temperature regimes reflect overwintering temperatures across the parasitoid’s geographical distribution in its native range. Results showed that the parasitoid resumed its development to the adult stage at normal rearing conditions (22°C, 100%RH, 14L:10D) after 6 or 7 months cold chilling at both natural and laboratory conditions. It had a low survival rate (36.7%) on potted plants due to desiccation or tree wound defense response. No parasitoids survived at 44% RH, but survival rate increased with humidity, reaching the highest (93.7%) at 100% RH. Survival rate also increased from 21.0% at 2°C to 82.8% at 12.5°C. Post-diapause developmental time decreased with increased humidity or temperature. There was no difference in the lifetime fecundity of emerged females from 2 and 12.5°C. These results suggest that 100% RH and 12.5°C are the most suitable diapause conditions for laboratory rearing of this parasitoid.