INHIBITION BY KINOPRENE OF PHOTOPERIOD-INDUCED MALE PRODUCTION BY APTEROUS AND ALATE VIVIPARAE OF THE APHID MYZUS-PERSICAE

Photoperiod-induced male production by apterous and alate viviparae of the green peach aphid. Myzus persicae, was reduced or prevented by treating the aphids with the JH analog kinoprene (Zoecon's insect growth regulator ZR 777). Concomitant with this reduction in the number of males was an increase in the production of females. This was most clearly demonstrated for apterous viviparae that had been raised from birth under weak long-night regimes of 10-10.5 hr dark day, and exposed to 0.1% kinoprene-treated radish seedlings for 2-3 days on reaching the fourth larval instar or adulthood. Male production by alate viviparae, whose apterous mothers were born and raised for 5 days under a long-night regime of 15 hr dark day and then maintained under a short-night regime of 8 hr dark day, was completely inhibited by exposing them to kinoprene-treated plants for 2-3 days when they had reached the fourth instar. It is concluded that the kinoprene treatment affects sex chromosome replication in the oögonia of an aphid so that these germ cells develop parthenogenetically into females (2n = 12 with two X chromosomes) rather than males (2n = 11 with one X chromosome). This may result either from a direct action of absorbed kinoprene on the oögonia or from an indirect action whereby the kinoprene stimulates the insect's hormonal system to produce a hormone that stimulates development of the oögonia into females. © 1979.