Parthenogenesis in the Coleoptera

Abstract

IN the “concluding remarks” in his treatise on “Wahre Parthenogenesis” (1856), von Siebold says, “Es ist daher jetzt Aufgabe der Entomologen, nach weiteren Beispielen von Parthenogenesis in der Insektenwelt zu forschen”; and on the last page (237) of his “Beiträge zur Parthenogenesis,” published fifteen years later, he expresses the conviction that many facts relating to this phenomenon are still to be discovered. The instances of true parthenogenesis discussed or referred to in these two works relate to insects of the orders Hymenoptera and Lepidoptera, and to some crustaceans. Including viviparous agamogenesis, however, as parthenogenetic, the orders Hemiptera and Diptera also furnish examples of this mode of reproduction; and for its occurrence in at least one genus of the Trichoptera I have the authority of Mr. R. McLachlan, F.R.S. The possibility of parthenogenetic reproduction in the Coleoptera rests only, so far as I am aware—see “Comparative Embryology,” by F. M. Balfour, vol. i. p. 64—on the single instance communicated by me to this journal last year (Nature, vol. xx. p. 430), and this being so, it seemed desirable to make sure of this point by further research during the season now almost past. Accordingly I have this year kept a considerable number of females of Gastrophysa raphani, laying unimpregnated eggs, and with results which have not only confirmed the previous experience, but much extended it, as I am at present in possession of a living beetle reared from a parthenogenetic ovum. With your permission I shall now endeavour as briefly as possible to give those circumstantial details without which a bald statement of results would not carry with it a rational conviction of the accuracy of my observations.