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huang luan de yan jiu . jin shui dui yu huang luan pei tai fa yu he si wang de ying xiang
Pages: 287-305
Year: Issue:  4
Journal: Acta Entomologica Sinica

Keyword:  胚胎发育蝗卵东亚飞蝗死亡率不同发育期卵块耗氧量孵化百分率顺向移动自来水;
Abstract: It is well known that the oriental migratory locust is used to breed in the waste drained riverbeds and the low lands adjacent to lakes and sea shores. When the water levels of the water bodiesbecome raised in the autumnal months, these places would get overflooded; and the egg-podswhich have been laid in these places are then subject to submersion for various lengths of time.The present work was carried out in the field as well as in the laboratory, with the view toclarifying what effects of immersion will have on the embryonic development of the eggs andhow long they can survive under water. Laboratory study showed that eggs in different developmental stages all could continue em-bryonic development under water so far as the temperature remained suitable. Aside from theindividual difference which appeared to be considerable in the present study, the extent ofdevelopment to which the eggs would proceed varied with the original developmental stages. Itwas seen that eggs originally in the early stages could develop better under water than thosewhich were in the later stages. Eggs belonging to the former categories might absorb water andform serosal cuticle in the immersed condition. Some of the newly-laid eggs and the eggs con-taining fully-developed embryos would burst under water; but the half-developed eggs wouldnever do so. This phenomenon is explained on the basis of the changes in the egg coverings asdevelopment proceeds. The newly laid egg only possess the primary protective structure; thussometimes they cannot withstand the superfluous penetration of water into the eggs. In the half- developed eggs, very effective secondary protective structure has been formed; and thus the eggscan resist the penetration of water very well. Eggs containing mature embryos unexceptionallyhave their serosal cuticle partially digested to ficilitate the hatching process; and they thus canbreak easily under water. The mature embryo thus released into water will soon be drowned. Theadverse effect of immersion manifests in the delay of embryonic development when the eggs arerestored to favorable environment for incubation. The capacity of the eggs to survive immersion is considered to be dependent upon thefollowing factors: (1) the developmental stages of the eggs; (2) the lengths of time immersed;(3) the temperature of the water; and (4) the gaseous contents of the water. In the laboratory,the most resistant stage was ascertained to be the half-developed eggs with their embryos justhaving completed anatrepsis. It is thought that their greater resistance is due to (1) the presenceof the highly effective secondary protective structure in the egg coverings to withstand the pene-tration of water; and (2) the relatively low rate of oxygen consumption. Contrary to the resultsobtained by Remaudiere with the eggs of Locusta migratoria gallica, it was found that the eggsof the oriental migratory locust could not survive immersion for one month when the watertemperature was 30℃. The eggs of Oedalus and Oxya, which would enter diapause when theembryos had completed anatrepsis, were found able to survive 60 days when immersed in waterwith a temperature of 30℃. That the eggs of the oriental migratory locust could not surviveimmersion at that temperature so long is explained on the basis of the fact that these eggs lacka diapause stage, which, when present, will occur when the embryos complete their anatrepsiswith the secondary protective structure in the egg coverings fully developed. Thus these eggswhen immersed in water will undergo embryonic development to that extent where the eggsenter the stage of much less resistance and thus are killed by immersion. Water temperature in the present work appeared to play a very important role in decidingthe mortality rate of the immersed eggs. It acts by changing the gaseous content of the water,raising the respiratory and developmental rates of the egg, and increasing the penetrating powerof water. Data from laboratory study show that the duration of survival can be prolongedwhen the water temperature is ke
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