|LEAKE, LAYNE - UNIVERSITY OF MISSOURI|
|Morrison Iii, William - Rob|
|LARA, JESUS - UNIVERSITY OF CALIFORNIA|
|HODDLE, MARK - UNIVERSITY OF CALIFORNIA|
|THOMAS, ELIJAH - FLORIDA DEPARTMENT OF AGRICULTURE|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2020
Publication Date: 2/8/2021
Citation: Ludwick, D.C., Leake, L.B., Morrison III, W.R., Lara, J.R., Hoddle, M.S., Thomas, E.J., Leskey, T.C. 2021. Influence of holding conditions and storage duration of Halyomorpha halys (Hemiptera:Pentatomidae) eggs on adventive and quarantine populations of Trissolcus japonicus (Hymenoptera:Scelionidae) behavior and parasitism success. Environmental Entomology. 50(3):550-560. https://doi.org/10.1093/ee/nvaa183.
Interpretive Summary: Trissolcus japonicus, also known as the samurai wasp, is one of the most effective biological control agents for brown marmorated stink bug (BMSB). This wasp requires BMSB egg masses to reproduce in the field and in the laboratory. However, it is not known how best to store egg masses or for how long to rear wasps optimally. We found that freezing BMSB egg masses at -80°C was as effective as fresh egg masses for rearing the wasp. However, freezing egg masses at higher temperatures (-20°C, -40°C) resulted in a decline for the number of wasps produced from egg masses. We found no patterns in the wasp’s behavior in response to these different treatments, suggesting other factors influence how it finds BMSB egg masses in the field. These results provide the basis for storing BMSB eggs and maintaining robust, continuous colonies of the samurai wasp.
Technical Abstract: Halyomorpha halys (Stål) (Pentatomidae: Pentatominae) is an invasive pest in the USA and other parts of the world. In its native range of East Asia, H. halys eggs are parasitized by its co-evolved parasitoid, Trissolcus japonicus (Ashmead) (Scelionidae: Telenominae). In the USA, T. japonicus is a candidate for classical biological control and is being redistributed in many states where adventive populations have been discovered. To establish if holding conditions of H. halys eggs affect T. japonicus foraging behavior or successful parasitism, naïve, female parasitoids from an adventive population were allowed to forage in laboratory bioassay arenas with either fresh or frozen egg masses (held at either -20°C or -80°C for 1 h–112 d) with movements recorded by Ethovision for one hour following release. Thereafter, parasitoids were transferred to small vials with the same egg mass for 23 hours. Additionally, female parasitoids from the Beijing quarantine colony were exposed to: 1) pairs of fresh egg masses and egg masses frozen at -40°C (>24 h), or 2) a single fresh egg mass or egg mass frozen at -40°C (<1 h). All exposed egg masses were then held to assess progeny emergence. In the foraging bioassay, holding temperature (-80°C or -20°C) and storage duration appeared to influence host-finding and host quality. Egg masses held at -80°C and fresh egg masses resulted in significantly greater levels of parasitism and progeny emergence when compared with eggs held at -20°C. Additionally, a bioassay with the Beijing colony resulted in reduced emergence from egg masses held at -40°C for =24 h compared with fresh egg masses. No differences were recorded between egg masses held at -40°C for =1 h and fresh egg masses. These results will help refine methods for preparation of egg masses for sentinel monitoring and parasitoid mass rearing protocols.