Gelman D B., Blackburn M B., Hu J S.
USDA - Agricultural Research Service, Insect Biocontrol Laboratory, Plant Sciences Institute, Rm 323, Building 306, 10300 Baltimore Avenue, BARC-East, 20705-2350, Beltsville, MD, USA
J Insect Physiol. 2002 Jan;48(1):63-73. doi: 10.1016/s0022-1910(01)00146-9.
A system of markers has been devised to track the development of 3rd and 4th instar/pharate adult greenhouse whiteflies. Instars were identified based on measurements of body width and body length. Depending upon the host plant, the product of the two measurements was exceptionally useful in distinguishing between instars. Body depth was used to divide the 3rd instar into eight stages and body depth and color and appearance of the developing adult eye were used to divide the 4th instar/pharate adult into nine stages. Under conditions of L:D 16:8 and a temperature of 26+/-2 degrees C, the body depth of 3rd instars reared on greenbean increased from 0.025 (stage 1) to 0.2mm (stage 8) and the instar duration was approximately 3 days. The body depth of 4th instars increased from approximately 0.1+/-0.02 (Stage 1) to 0.3+/-0.03mm (Stage 5) and then remained constant or decreased slightly during adult development. Ecdysteroid titers peaked at approximately 120fg/&mgr;g protein during Stages 3 through 6 of the 4th instar. Based on an external examination of developing 4th instars and the fluctuations in ecdysteroid titer, it appears that adult development is initiated in Stage 4 or 5 4th instars. Results from histological studies support this view. In Stage 4 nymphs, a subtle change was observed in the corneagenous cells of the eye. However, most Stage 4 4th instars possessed wing development characteristic of earlier, immature stages. In all Stage 5 insects, wing development had been initiated and the corneagenous cells had become quite distinct. In Stage 6 whiteflies, the wing buds were deeply folded and by Stage 7, spines were observed on the new cuticle, indicating that the adult cuticle was well-formed by this stage. Our study is the first to investigate the timing and regulation of the molt, to monitor ecdysteroid titers in precisely staged 4th instar whiteflies and to examine the internal anatomical changes associated with metamorphosis in these tiny homopteran insects.
已经设计了一套标记系统来追踪温室白粉虱三龄和四龄/准成虫期的发育情况。龄期是根据体宽和体长的测量结果来确定的。根据寄主植物的不同，这两个测量值的乘积在区分龄期方面非常有用。体深被用来将三龄期分为八个阶段，体深以及发育中准成虫眼睛的颜色和外观被用来将四龄/准成虫期分为九个阶段。在16:8的光暗周期和26±2摄氏度的温度条件下，在绿豆上饲养的三龄若虫的体深从0.025（第1阶段）增加到0.2毫米（第8阶段），龄期持续约3天。四龄若虫的体深从大约0.1±0.02（第1阶段）增加到0.3±0.03毫米（第5阶段），然后在成虫发育过程中保持不变或略有下降。蜕皮甾类滴度在四龄期的第3至6阶段达到峰值，约为120fg/μg蛋白质。根据对发育中的四龄若虫的外部检查以及蜕皮甾类滴度的波动情况，似乎成虫发育在四龄期的第4或5阶段开始。组织学研究结果支持这一观点。在四龄期第4阶段的若虫中，眼睛的角质形成细胞观察到细微变化。然而，大多数四龄期第4阶段的若虫具有早期未成熟阶段的翅发育特征。在所有第5阶段的昆虫中，翅发育已经开始，角质形成细胞变得非常明显。在第6阶段的白粉虱中，翅芽深深折叠，到第7阶段，在新表皮上观察到刺，表明到这个阶段成虫表皮已经发育良好。我们的研究首次调查了蜕皮的时间和调控机制，并监测了精确划分阶段的四龄期白粉虱的蜕皮甾类滴度，还研究了这些微小同翅目昆虫变态过程中相关的内部解剖变化。
