G. Smagghe et al., EFFECT OF NONSTEROIDAL ECDYSTEROID AGONISTS ON ECDYSTEROID TITER IN SPODOPTERA-EXIGUA AND LEPTINOTARSA-DECEMLINEATA, Journal of insect physiology, 41(11), 1995, pp. 971-974
In control last-instar larvae of Spodoptera exigua, and Leptinotarsa d
ecemlineata, major hemolymph ecdysteroid peaks appeared around day 3-4
, and 8-9, respectively, which is correlated with normal apolysis. Lat
er on, hormone titers declined to a basal level, In Colorado potato be
etle last-instars, a small rise was noted around day 4, which represen
ts the time of digging, In last-instar larvae of S. exigua treated wit
h either RH-5849 or tebufenozide, the ecdysteroid titer remained at a
basal Level without any elevation, Such larvae showed signs of untimel
y apolysis within 12-24 h after treatment followed by cessation of fre
sh weight gain, Likewise, hemolymph ecdysteroid levels and larval weig
ht gain were reduced in last-instar larvae of L. decemlineata treated
with RH-5849 as compared with controls, Otherwise, treatment of Colora
do potato beetle larvae with tebufenozide caused no hormonal and physi
ological abnormalities as compared with controls, It is suggested that
both nonsteroidal ecdysteroid agonists act via ecdysteroid receptor b
inding without an increase in ecdysteroid titer.