Life-History Traits of a Subtropical Cerambycid Beetle, Ropica honesta (Coleoptera: Cerambycidae).

Abstract

Ropica honesta Pascoe is a small-sized cerambycid that has been recorded in tropical to subtropical Asia. In this study, life-history traits were examined for a local population collected from Iriomote Island (24.3°N, 123.8°E), Okinawa, Japan, by rearing insects on artificial diet as larval food. The egg period was 5.9 ± 0.3 d at 25°C. There was no significant difference in the duration of the larval, pupal, and adult preoviposition periods between long-day (14:10 [L:D]) and short-day (12:12 [L:D]) photoperiods at both 20 and 25°C. These periods at 25°C (14:10 [L:D]) were 28.5 ± 1.4, 8.4 ± 0.5, and 9.6 ± 1.9 d (mean ± SD), respectively. The relationship between the developmental rate and temperature followed the law of total effective temperature; thus, the developmental threshold temperature and thermal constant were estimated based on these data. Together with the finding that R. honesta may not have diapause in the egg stage, it is suggested that this beetle does not have diapause in the life cycle. Furthermore, when larvae were reared on natural food (dead twigs of hardwoods) adults emerged from the twigs 47.6 ± 2.9 d after oviposition, and this value was close to the total duration of the egg to pupal periods. Together with the data for annual temperature of the habitat and the fact that food resources for the species (dead twigs and leaves of hardwoods) are available throughout the year, we conclude that R. honesta develops and reproduces all year round, with five generations at maximum.