O. Merkl szerk.: Folia Entomologica Hungarica 68. (Budapest, 2007)

BIONOMICS Gleditsia triacanthos is planted in Europe since the early 1700s (GENCSI & VANCSURA 1992), and it is a popular ornamental tree planted singly, in groups or lining roads throughout Hungary. Megabruchidius tonkineus is a good flier, it can find the host plant even ifit is located streets away. Females lay the eggs singly on the mature pod. Because of the tough pod wall, the female prefers pods with surface damages, where larvae can enter easily (T. JERMY, personal communication). The ovipositor is suitable for reaching the inside of the pod. When opening pods I observed egg shells on the surface of seeds immediately under an exit hole on the pod wall. This behaviour enables the insect to utilize even older, already used pods remaining on the ground from previous years. On several occasions I collected pods where all seeds were damaged. This, however, does not mean that only damaged pods or pods with exit holes are used for egg laying; in the nature, the nooks in strongly spiralised undamaged pods also had eggs. In the laboratory females kept in petri dishes preferred laying eggs (second only to the seeds) also on the honey-watered rolled tissue paper (intended as a food source for the adults), perhaps because of its moisture and texture (deep creases). Females laid eggs into the exit holes of already damaged seeds. Also commonly used egg laying site was the cloth covering the rearing dishes. Such erroneous egg laying does not cause serious problems for the larvae, as they can move very vividly, with gently waving motions. I could observe a female laying her first egg on the second day after mating. By the seventh day there were ten eggs. At room temperature, the first egg hatched on the fourteenth day, followed by the second on the twentieth day; three eggs died. The seven living larvae were further observed. Figs 10-13. Megabruchidius tonkineus (PIC, 1904): 10 = anterior part of head, ventral view, 11= prothoracic plate, 12 = pupa, 13 = wing. Not to scale