(041011 revised, 041011 created)
Munyiri FN, Shintani Y, Ishikawa Y. (2004)
Evidence for the presence of a threshold weight for
entering diapause in the yellow-spotted longicorn beetle,
Psacothea hilaris.
J Insect Physiol. 2004 Apr;50(4):295-301.
Under long-day conditions larvae of Psacothea hilaris
(Coleoptera: Cerambycidae) pupate after the 4th or 5th
instar, while under short-day conditions they undergo 2-4
nonstationary supernumerary molts and eventually enter
diapause. To explore the possibility of a threshold weight
for entering diapause, P. hilaris larvae were deprived of
food on days 0 (day of ecdysis), 4 or 8 of the 4th, 5thand 6th instars under short-day conditions. Within the first 40 days of starvation, 60% of the larvae starved starting on day 0 of the 4th instar died, but all the
larvae starved at later stages survived. The incidence of diapause in these survivors was determined by the occurrence of pupation after a temporary chilling at 15 degrees C for 15 days. Diapause incidence increased as the
onset of starvation was delayed; from 11% in the larvae starved on day 0 of the 5th instar to 100% in the larvae starved on day 4 and day 8 of the 6th instar. Analysis of the relationship between the initial weight of a
respective larva at the onset of starvation and its pupation success revealed that none of the larvae weighing 690 mg did. This finding suggests the presence of a threshold
weight (about 600 mg), below which larvae are incapable of entering diapause. We discuss these findings withreference to the life history of P. hilaris.
Psacothea hilaris:English name:
yellow-spotted longicorn beetle. Japanese name:.Kiboshi Kamikiri, キボシカミキリ