Abstract
The host plants and seasonal occurrence of larvae and pupae of Omphisa anastomosalis were examined on Kume Island through the extensive collection of convolvulaceous host candidates from 2001 to 2010. The frequency of infestation was highest on Ipomoea indica (5.8 insects per 100 m of vine) followed by sweet potato (2.1 insects). Other Ipomoea spp. were infested rarely or not at all (<0.6 insects). On I. indica, infestation frequency was negatively correlated with air temperature, with a large peak from January to February. The pupal ratio among the total population showed two clear peaks in June and October, and was zero or nearly zero in August and from December to April. These results suppose that at least two generations occur within a year, and may suggest a delay of larval development due to low temperatures in winter and the inhibition of pupation by high temperatures or other unknown factor(s) in summer. Further, the infestation frequency of I. indica decreased from April to July, while it increased or did not change in the sweetpotato field during this period.
