a1 Department of Entomology, The University of Queensland, Brisbane, Queensland 4072, Australia
Although Aphytis lingnanensis Compère is an important parasitoid of California red scale Aonidiella aurantii Maskell, several ‘races’ of A. lingnanensis exist which parasitize white louse scale Unaspis citri Comstock. The reproductive status of a white louse scale ‘race’ of A. lingnanensis that originated in Thailand was examined in relation to several populations (from Queensland, California and the Philippines) that parasitize California red scale. None of the wasps from red scale mated with individuals from white louse scale in small cages within 10 min, whereas control crosses all mated in that time. The two ‘races’ would therefore constitute independent reproductive entities (species) in sympatry in the field, although no consistent anatomical differences could be found between them, even with the aid of discriminant function analysis on the number of setae on the delta region of the forewing and the mesoscutum.
Aphytis lingnanensis from California red scale in Queensland mated readily with wasps derived from the same host species in California and the Philippines, and mating took place at random among individuals in mate choice tests. Although such results are equivocal, there are no reasons for suspecting that these different populations of A. lingnanensis from California red scale also comprise more than one species. The results obtained indicate that cross-mating tests designed to quantify reproductive isolation between sexual populations are inappropriate. They should rather be designed to establish whether individuals recognize one another as potential mates. The design of cross-mating tests should therefore consider the usual time to mating, of known conspecifics, under the experimental conditions to be used.
(Accepted September 25 1996)
c1 Author for correspondence.
p1 Present address: Crop Protection Division, Coconut Research Institute, Lunuwila, Sri Lanka.