Diploid arrhenotoky and automictic thelytoky in soft scale insects (Lecaniidae: Coccoidea: Homoptera)

Abstract

Parthenogenesis is reported in three soft scales with 2n=16. In the unfertilized eggs of all three, oogenesis is normal and diploidy is restored by the fusion of the division products of the haploid female pronucleus. In Lecanium putmani Phillips 12 of 13 uninseminated females collected in the wild produced only males. The 21 inseminated females produced 15% males. The males were diploid but contained one euchromatic (E) and one heterochromatic (H) chromosome set. Most of the eggs produced by the inseminated females contained sperm but a few did not. It was concluded, therefore, that females develop from fertilized eggs and males from unfertilized eggs and that the species was diploid arrhenotokous. In L. cerasifex Fitch only 18 of 56 females collected in the wild had been inseminated. The frequency of males among their embryos was 22%. The males were again diploid with one E and one H set of chromosomes. Among the 38 uninseminated females, 27 produced only males, and 10 produced only females. All the female producers contained needle-like bacterial symbionts. Most of the male producers, and most of the inseminated females contained no symbionts; the rest contained rod-like symbionts. It was concluded, therefore, that the females of L. cerasifex studied belonged to two races, a diploid arrhenotokous race and an obligate automictic thelytokous race. Eucalymantus tessellatus (Signoret) is obligate automictic thelytokous. All the females examined were uninseminated and produced only females.