St. Trumbo et al., RAPID ELEVATION OF JUVENILE-HORMONE TITER DURING BEHAVIORAL-ASSESSMENT OF THE BREEDING RESOURCE BY THE BURYING BEETLE, NICROPHORUS-ORBICOLLIS, Journal of insect physiology, 41(6), 1995, pp. 535-543
Female burying beetles (Nicrophorus orbicollis) rapidly complete ovari
an maturation upon discovering a suitable carrion resource for breedin
g, In this study, we examined changes in hemolymph titers of juvenile
hormone (JH) over the first 30 days of adult female life, and in respo
nse to the discovery of a mouse carcass, Levels of JH were found to in
crease gradually over the first 20 days, and then increased abruptly w
ithin 24 h of discovery of a carcass, Changes in JH titer were correla
ted with increases in ovarian mass and length of terminal oocytes, To
more precisely determine the timing of the endocrine response to a car
cass, hemolymph titers of JH were measured 2, 10, 20 and 60 min after
carcass discovery, Titers of JH were significantly elevated (112% over
controls) in just 10 min, To confirm this resource discovery-related
increase in JH, hemolymph samples were taken from the same individuals
both 2 days before, and 10 min after, discovery of a carcass, Again,
JH titers rose significantly (170%) in beetles 10 min after carcass di
scovery, Prominent behaviors observed during the 10-min period followi
ng discovery included palpating, lifting, walking around the carcass a
nd making forays into the surrounding soil, Feeding did not occur, The
se results suggest that the rapid JH surge in female burying beetles i
s triggered by information obtained during behavioral assessment of a
breeding resource, and not by mating or feeding cues, The association
between ovarian development and JH titer further suggests a role for J
H in co-ordinating reproduction in a temporally and spatially unpredic
table environment.