SCOTT, M.P.: Social and Environmental Factors that Do and Do Not Affect Juvenile Hormone of Burying Beetles

Burying beetles use small vertebrate carcasses that they bury and prepare as a breeding resource. They have facultative bi-parental care and commonly both male and female beetles (Nicrophorus orbicollis) remain in the burial chamber to feed and guard larvae after eggs hatch. Juvenile hormone (JH) rises significantly within minutes of the discovery and assessment of a carcass. JH returns to near baseline after 24 hours and, in females, rises again to very high titers when larvae first appear then returns to baseline after 2 days. I tested the hypotheses that carcass size, the presence or absence of a mate during the initial stages of burial, and the stimuli from first instar larvae might have an effect on the JH profile in females. Even though large carcasses took longer to prepare than small ones and oviposition was delayed, there were no significant differences after 2 or 12 hours in JH hemolymph titers of females burying large or small carcasses. Social stimuli from a mate had no effect on JH titers; there were no significant differences after 2 or 12 hours in JH of virgin females, non-virgin females without a mate and paired females. However, stimuli from begging first instar larvae promoted high JH titers; females whose larvae were replaced with newly hatched first instars every 24 hours for three days still had very high JH titers whereas those rearing a consistent brood of larvae that were 3rd instar by the third day had low JH.