Research On The Morphological Structure And Development Of Spodoptera Litura Prothoracic Glands And Gonads

Spodoptera litura, also known as Prodenia litura, belonged to Lepidoptera,Noctuidae. Spodoptera litura was a worldwide omnivorous agricultural pest and itoutbroke frequently in China in recent years, damaging the field crops and vegetables.Now in China, the major control to S.litura was chemical pesticide. However, theabuse of chemical pesticide damaged the environment and led that the S.lituradeveloped strong drug resistance. Therefore, we need to do more research onphysiological function of the S.litura to find efficient method to control the S.litura.Prothoracic glands and gonads (spermaries and ovaries) were importantendocrine organs in insects. The functions of prothoracic glands were synthesizingand secreting ecdysone, which controlled insects’ growth, development and ecdysis.Gonads produced sperms and ova to multiply insect population. These two glandsplayed an important part in insect developing and breeding. The S.litura’sdevelopment and growth law were studied to find ways of weakening and blockingtheir functions, which would provide the S.litura control with new way.This paper focused on prothoracic glands and gonads and applied artificial rearing, microanatomy, protein electrophoresis method to observe and study themorphological structure and growth of prothoracic glands and gonads. This wouldprovide new efficient way of controlling the S.litura with experiment basis and theoryguidance.The prothoracic glands of S.litura were in pair with Y-type, consisted of53roundor oval cells and surrounded with transparent vaginal tunica. From4thinstar larvae topupa, the number of prothoracic gland cells had no significant difference and nomitosis, so we inferred prothoracic gland cells had no cell division. We found thediameter of S.litura prothoracic glands and the weight and length of S.litura hadsignificant relevance by correlate analysis. The diameter of prothoracic gland cellsand weight of larvae fitting curve equation: Y=82.1X0.263. The diameter ofprothoracic gland cells and length of larvae fitting curve equation: Y=e(4.781-1.863/Z).We cultured120prothoracic gland cells in29℃Grace’s culture solution for6hours and made cell homogenate and culture solution sample implement SDS-PAGEelectrophoresis. The result showed there was no significant prothoracic gland culturesolution band.The spermaries of S.litura were located between the second and third proleg nearthe back, parallel and kidney-shaped. They fused together into globosity structure inpupa. The long axis of spermaries increased from462.28±12.17μm at the1stday of4thinstar to2130.77±73.41μm at the4thday of6thinstar and decreased to1900.98±47.06μm in prepupa stage. The minor axis of spermaries was266.89±6.94μm at the1stday of4thinstar, It increased to1345.04±53.38μm at the3thday of6thinstar andmaintained at1300μm from the end of6thinstar to prepupa stage. After the twospermaries fused, the diameter of spermaries increased steadily in pupa and decreasedin adult until the S.litura died. We found the long axis length of S.litura spermariesand the weight and length of S.litura had significant relevance in larval stage bycorrelate analysis. We also found the minor axis length of S.litura spermaries and theweight of S.litura in larval stage had significant relevance. However, the minor axislength of S.litura spermaries had no significant relevance with the length of S.litura.In larval stage, ovaries were translucent opalescent, oval and surrounded with transparent membrane. In adult, ovaries differentiated8ovarioles. Ovariole was longand transparent with ovum arranging densely. We divided5stages by ovariesmorphological characteristics, and they were transparent opalescent stage, yolkdeposition stage, premature stage, mature and oviposition stage, post-ovipositionstage. The long axis of ovaries was143.31±12.96μm at the1stday of4thinstar andincreased to591.55±86.24μm on the2ndday in prepupa stage. The minor axis ofovaries increased from110.1±12.56μm at the1stday of4thinstar to315.1±43.61μmat the3rdday of6thinstar and maintained at310μm from the end of6thinstar toprepupa stage. The length of variole increased in pupa and decreased in adult until theS.litura died. We found the long axis length of S.litura ovaries and the weight andlength of S.litura in larval stage had significant relevance by correlate analysis.However, the minor axis length of S.litura ovaries had no significant relevance withthe weight or length of S.litura.