Zoology Department, University of Auckland, Private Bag, Auckland, New Zealand.
*Present address: Insect Mass Rearing Unit, The International Centre of Insect Physiology and Ecology (ICIPE), P.O. Box 30772. Nairobi. Kenya (East Africa).
Close monitoring of laboratory colonisation and successive rearing of the lepidopteran leaf roller, Cnephasia jactatana on artificial diet revealed no distinct impact on the life cycle. The second laboratory generation had prolonged development time and dilrerent sex synchronism in pupation and eclosion patterns. Most deleterious changes observed in latter generations (decrease in fertility, egg hatch, sperm motllity; failure for mating adults to separate, pupal and adult malformations) were due to incompatibility to the general purpose diet (GPD) and were absent under sub-colonisation on the sheep nut-bean based diet (SBD). Success in the laboratory colonisation of C. jactatana is attributed to a random mating protocol, choice of environmental variables and a rapid rate of population growth. Rather than a true adaptive process, laboratory colonisation is proposed to depend on the plasticity of the tolerance limits in insect species. Insects will establish successfully in captivity if the magnitude of environmental variables are within the insects ranges of colonisatinn. Optimum physiological and behavioral responses are obtained when the variables are within the smaller preferred range of colonisation. Other concomitant processes at colonisation are selection, acclimatisation and domestication. Definition of the terms ‘adaptation’ ‘acclimatisation’ and ‘domestication’ commonly misused in describing processes during laboratory colonisation are proposed.
