In vitro heat tolerance at different life stages of Marula, Natal and Mediterranean fruit flies (Diptera: Tephritidae).
Graaf J. de
Author Affiliation: Westfalia Tegnologiese Dienste, Posbus 1103, Tzaneen 0850, South Africa.
27 : 43-48
Abstract : The Marula (Ceratitis cosyra), Natal (C. rosa) and Mediterranean (C. capitata) fruit fly attack ripening mangoes and are quarantine pests in Asia and the USA. Eggs are laid in fruits. These pests develop through 3 larval instars before pupating in the soil. The USA, China and India require exporting countries to employ a postharvest mitigation treatment for fruit flies and the most suitable method for South African mangoes is hot water treatment. In vitro heat tolerance in the Marula, Natal and Mediterranean fruit flies was studied. Eggs, young larvae (first and second instars) and mature larvae (third instar) were obtained from laboratory colonies and exposed to water for 10 different time intervals at 44 and 46°C. Abbott's correction was employed, and probit, logit and log-log transformations were used to model the relationship between temperature and mortality. The data showed that the Marula fruit fly was the most tolerant of heat in the water medium. The relative heat tolerance between the life stages of the Marula fruit fly was dependent on temperature, but at 46°C, the larvae of the marula fruit fly were the most tolerant of heat.