Pg. 59-60 Laboratory rearing of the litchi moth, Cryptophlebia peltastica (Lepidoptera: Tortricidae)

The litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) is a pest of litchi, Litchi chinensis Sonnerat, in South Africa. The female lays her eggs on the skin of the fruit and newly hatched larvae eat through the skin and into the fruit flesh and seed. The aim of the present study was to rear high numbers of the litchi moth in captivity for future research. Infested litchi fruit was collected at 3 different locations during the growing season. Final instar larvae found in the fruit were placed in plastic containers with sand for the larvae to pupate in. Pupae found were placed in boxes for adult moths to emerge. Adults that emerged were collected and placed in a cage at 3 different temperatures and 3 different humidities. Eggs laid were placed singly into honey flasks with a steam sterilized maize meal medium. Not one of these eggs hatched. From the results found, it seems that the optimum temperature for egg laying is 30°C and relative humidity of 80% – 100% with a complete night cycle. Further work starting with many more individuals is required to establish a laboratory population.

Summary:

• The litchi moth (Cryptophlebia peltastica) is a significant pest of litchi fruit in South Africa, also found in Madagascar, Seychelles, Mauritius, and Reunion.
• Females lay eggs singly on the fruit skin; larvae burrow into the flesh and seeds, causing damage that sometimes leads to fruit rot or cracking.
• The study aimed to rear high numbers of litchi moths in the laboratory for research.
• Infested fruits were collected from three South African regions during the season.
• Final instar larvae were placed in sand-filled containers for pupation, and pupae were collected for adult emergence.
• Adults were kept in cages at varying temperatures (25°C, 27°C, and 30°C) and relative humidities (50%, 70%, 80-100%).
• Eggs were laid only at 30°C with 80-100% humidity and a complete night cycle; a total of 53 eggs were found under these conditions.
• Eggs were placed singly in sterilized maize meal growth medium in honey flasks, but none hatched.
• The maize meal medium used for rearing false codling moths is unsuitable for the litchi moth.
• A high number of individuals are needed to establish a lab population due to natural pupal mortality.
• Infestation was low in most areas except the Nelspruit farm, where most larvae were collected.
• Future work should explore alternative host plants and modification of the growth medium (including litchi juice, peel, flesh, or seed mixed in) to improve egg hatch and larval development.
• Temperature and humidity play critical roles in development and need further investigation specific to the litchi moth.
• The study adapted methods from false codling moth rearing but noted biological differences that challenge laboratory breeding efforts.