COMPARATIVE PROPENSITY FOR DISPERSAL OF APTEROUS AND ALATE MORPHS OF 3 POTATO COLONIZING APHID SPECIES

The relative ability of apterous and alate morphs of aphids to dispers e from one potato leaflet to another was similar within species. Three species were tested: the buckthorn aphid, Aphis nasturtii Kaltenbach, the potato aphid, Macrosiphum euphorbiae (Thomas), and the green peac h aphid, Myzus persicae (Sulzer). The average percentage of aphids mov ing daily from one leaflet to another never exceeded 2.5% for nymphs o f the three species, but reached 45% for the adult winged buckthorn ap hid. During the first half of the reproductive period, adult potato ap hids were 1.5 times as likely as buckthorn aphids and twice as likely as green peach aphids to relocate daily. In a flight chamber, buckthor n aphids flew 4.5 times longer than green peach or potato aphids. The maiden flights of these summer forms were interrupted by repeated land ings lasting less than 2 min. The maiden flights were interrupted more than twice as often for the buckthorn aphid as for the potato aphid. The number of flight interruptions was intermediate for the green peac h aphid. Selected dispersal parameters for these aphid species are com pared with those for the black bean aphid, Aphis fabae Scopoli, an occ asional potato-colonizing species. The percentage of green peach and p otato aphids taking flight was significantly correlated with the tempe rature in the flight chamber. The implication of these results for the distribution of aphid populations and the epidemiology of viral disea ses is discussed.