Influence of holding temperature and irradiation on field performance of mass-reared Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

Authors: BOERSMA, NEVILL - Xsit (PTY) Ltd; Carpenter, James

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2015
Publication Date: 6/1/2016
Citation: Boersma, N., Carpenter, J.E. 2016. Influence of holding temperature and irradiation on field performance of mass-reared Thaumatotibia leucotreta (Lepidoptera: Tortricidae). Florida Entomologist. 99(sp1):215-221. doi:10.1653/024.099.sp126.

Interpretive Summary: The false codling moth, Thaumatotibia leucotreta, is native to sub-Saharan Arica, infests a large number of agricultural and wild fruit-bearing plants, and is a phytosanitary pest of concern for the United States and other countries. The Sterile Insect Technique (SIT) as an integral component to the area-wide integrated management of the false codling moth was successfully implemented in the Western Cape of South Africa and subsequently expanded to citrus area in the Eastern Cape of South Africa. This integrated control program which transports sterile moths from an insectary in Citrusdal, South Africa to orchards in both the Western and Eastern Cape must continuously examine production, handling, transport, and release protocols to insure the delivery of high-quality sterile moths. While the use of cold temperature to immobilize moths is standard protocol for SIT programs to increase the density of moths for purposes of collecting, holding, irradiation, transport and release, some concern has been raised that rapid chilling and long storage of moths may negatively impact field performance of some laboratory-reared insects. We conducted trials to examine the effect of cold temperature storage and subsequent irradiation (with gamma rays of 150 Gy) on the performance of T. leucotreta moths released in citrus orchards. Compared to moths manually collected from the emergence cabinets in the insectary and held at room temperature, moths collected in the insectary air stream and rapidly chilled were less likely to be captured in pheromone traps and less likely to disperse as great a distance following release in citrus orchards. Continuous quality monitoring and additional research are required to identify further procedural changes that would maintain or enhance T. leucotreta moth quality and performance while allowing for the cost-effective handling of the sterile moths.

Technical Abstract: The Sterile Insect Technique (SIT) as an integral component to the area-wide integrated management of the false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), was successfully implemented in the Western Cape region of South Africa and subsequently expanded to citrus areas in the Eastern Cape region of South Africa. This integrated control program, which transports sterile moths from an insectary in Citrusdal, South Africa to orchards in both the Western and Eastern Cape must continuously examine production, handling, transport, and release protocols to ensure the delivery of high-quality sterile moths. While the use of cold temperature to immobilize moths is standard protocol for SIT programs to increase the density of moths for purposes of collecting, holding, irradiation, transport and release, some concern has been raised that rapid chilling and long storage of moths may negatively impact field performance of some insectary-reared insects. We conducted trials to examine the effect of cold temperature storage and subsequent irradiation (with gamma rays of 150 Gy) on the performance of T. leucotreta moths released in citrus orchards. Compared to moths manually collected from the emergence cabinets and held at room temperature, moths collected in the insectary air stream and rapidly chilled were less likely to be captured in pheromone traps and less likely to disperse as great a distance following release in citrus orchards. Continuous quality monitoring and additional research is required to identify further procedural changes that would maintain or enhance sterile T. leucotreta moth quality and performance in the field while allowing for the cost-effective handling of the sterile moths.