A gynandromorphic grasshopper produced by double fertilization

Abstract

An individual of the large grasshopper Valanga irregularis (Walker) which exhibited bilateral gynandromorphism, is described. The entire right side was female, the left side being male. The colour pattern on the two sides was completely different, the male side corresponding to the concolorous phenotype, the female side to the contrasty one. The gonad was an undeveloped ovotestis, the testicular part being XO (2n = 23). There are two obvious explanations of this gynandromorph: (1) that a single XX zygote nucleus gave rise to XX and XO nuclei through loss of an X; in this case we would be dealing with a sex-linked pattern polymorphism, the gene for the contrasty morph being dominant to the concolorous allele; (2) that the gynandromorph arose from a binucleate egg, as a result of double fertilization. Data on the frequency of the morphs in the two sexes, in natural populations, do not support the first hypothesis, and it is concluded that the second one must be correct.