EFFECTS OF POPULATION-DENSITY EXPERIENCED BY PARENTS DURING MATING AND OVIPOSITION ON THE PHASE OF HATCHLING DESERT LOCUSTS, SCHISTOCERCA-GREGARIA

The behavioural phase state of first-instar desert locusts, Schistocer ca gregaria Forskal, was quantified by using logistic regression analy sis, following treatments in which the population density experienced by their mother during mating and oviposition was manipulated. Crowdin g during the period of oviposition caused females that had previously been reared in isolation to produce offspring which behaved in a grega rious manner. However, isolating previously crowd-reared females led t o hatchlings which behaved more solitariously. The population density experienced during mating affected the behaviour of larvae from solita ry-reared, but not crowd-reared, parents. These results show that the transmission of phase characteristics across generations can be modifi ed even at the final stage of the reproductive cycle, providing consid erable flexibility in response to changes in population density.