Pg. 32-35 Rearing sustainable laboratory cultures of litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae)

The principal objective was to develop a mass-rearing technique for sustainable cost-effective cultures of litchi moth, Cryptophlebia peltastica, for cold storage analysis trials. Infected fruit from litchi orchards and alternate host plants were collected on three field trips and were taken to Grahamstown using three forms of transport medium: on artificial diets, in situ in litchi pips, and in situ in pods and twigs collected from Pride of Barbados (Caesalpinia pulcherrima L. Sw.) plants. A total of 1 697 C. peltastica larvae were collected from over 8 500 individual fruit, pods and twigs; the rate of return was 20% of the apparently infested host plant material. Larvae were transferred to a Constant Environment (CE) room and reared on artificial diet to pupal stage. Emerging adults were placed in mating and oviposition cages from where eggs, in excess of 1 445 to date, have been transferred to jars containing artificial diet. A total of 50 C. peltastica adults have eclosed thus far, completing the first laboratory-reared generation of this project. During the course of this project insufficient numbers of larvae were collected to develop a fully sustainable mass-culture. The number of larvae collected from apparently infested fruit was extremely low, thereby necessitating repeated collection of plant material from a range of host plants.

Summary:

• The objective was to develop mass-rearing techniques for sustainable, cost-effective laboratory cultures of the litchi moth, Cryptophlebia peltastica, to support cold storage analysis trials.
• Larvae were collected from infected litchi fruit and alternate host plants (Pride of Barbados, Caesalpinia pulcherrima) during three field trips.
• Over 8,500 samples of fruit, pods, and twigs were dissected, yielding 1,697 larvae; overall larval recovery from infected samples was about 20%.
• Larvae were successfully reared on artificial diet in controlled environment (CE) rooms through to the pupal and adult stages.
• The first lab-reared generation was established, with over 1,445 eggs laid and 50 adults emerged.
• Maintaining sustainable cultures required repeated collection because larval numbers in the field were low, making continuous broodstock sourcing essential.
• Various transport media and techniques were developed to safely move larvae from field collection sites to the lab.
• Hygiene and sanitation practices were critical in preventing microbial contamination and maintaining healthy cultures.
• Issues such as egg fertility, ant infestations, and fungal outbreaks were encountered and managed during the project.
• The alternate host, C. pulcherrima, provided a more abundant source of larvae than litchi fruit, suggesting possible use as a trap crop.
• The study highlighted challenges but demonstrated the feasibility of establishing viable laboratory cultures for research and pest management purposes.
• The project was supported by statistical analysis, and funding was provided by the South African Litchi Growers Association.