Ecdysteroids in the larvae of Opogona sacchari （Bojer）, a invasive alien pest

In order to understand the composition and quantitative variation of ecdysteriods in the larvae of Opogona sacchari (Bojer), a invasive alien pest, we analyzed the larval ecdysteroid composition and titers in this pest. The main component of ecdysteriods in the larvae of O. sacchari is 20-hydroxyecdysone, and also there is a little 26-hydroxyecdysone. The titer of ecdysteriods in the larvae from the 1st instar to the 7th instar was gotten higher gradually compared on ng ecdyster-oid/larva, but no regularity could be found about the titer if compared on ng ecdysteroid/g avoirdupois. There was only one peak of ecdysteroids (0.5475 ng/larva) showed at day 2 during the developmental time of the 6th instar larvae. However, there were two peaks appearing during the developmental time of the 7th instar larvae , one peak (0.29415 ng/larva) at day 3, another (0.214 ng/larva) at day 5.     

Effects of no mating on the female adults and embryonic development of Schistocerca gregaria (Orthoptera: Acrididae)

The newly emerged adult females of Schistocerca gregaria were separated and kept in the rearing conditions without males to examine the detailed developmental characteristic of the no mating females and carefully observed the developmental progress of non-fertilised eggs laid by virgin females. The results showed that the females kept without males survived in average 43 d, i.e. 58% of the life span of mated controls, and laid correspondingly fewer egg pods. The size of egg batches, the weight of eggs, and their content of ecdysteroids were normal but the hatch rate was reduced to 18.27%. Blocks of early embryogenesis (58.43%) and hatching failures (23.29%) were the major causes of death. Moreover, most of the hatched insects died during the postembryonic development and only a few females reached the adult stage. All insects that developed until the penultimate or last larval instar or reached the adult stage were females.