Survival, longevity, growth index and development of fifth instar nymphs of Dysdercus koenigii (Heteroptera: Pyrrhocoriedae) as influenced by the Catharanthus roseus was assessed in the present investigation. The fifth instar nymphs were exposed to the volatiles present in the extract for 24 h. Different concentrations of the extract ranging from 0.00625% to 10% were used for the treatment. The results indicate that the survival of treated nymphs was not affected significantly. However, the volatiles present in the extract influenced the growth and development of the treated fifth instar nymphs. The nymphs exhibited decreased growth as reflected by the decrease in growth index. The extract induced different types of developmental anomalies notably incomplete moulting, supernumerary instars, adultoids and adults with deformed wing. In some cases, exuviae did not detach from the body of the adults and create obstacle in the feeding, walking and mating. The effects of the extract on nymphal development were also dose-dependent. No normal adults could develop in the treatments with the concentration 5% or more; various morphological and developmental abnormalities were reported in the nymphs treated with 2.5% to 0.1% of the extract. GC-MS analysis of the hexane leaf extract of C. roseus showed the presence of sesquiterpenes including geranylgerniol and many toxic chemicals. These phytoconstituents of the C. roseus extract besides having cidal effects also showed juvenile hormone mimic activities which impair lifetime fitness of D. koenigii. Therefore, botanical from the C. roseus can potentially be used as an alternative approach in pest management.

中文翻译：

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长春花正己烷提取物中的挥发物导致红棉蝽Dysdercus koenigii Fabricius的适应性降低

在本调查中评估了受长春花影响的 Dysdercus koenigii（异翅目：Pyrrhocoriedae）五龄若虫的存活率、寿命、生长指数和发育。五龄若虫暴露于提取物中存在的挥发物24小时。使用范围从 0.00625% 到 10% 的不同浓度的提取物进行处理。结果表明，处理过的若虫的存活没有受到显着影响。然而，提取物中存在的挥发物影响了处理过的五龄若虫的生长和发育。若虫表现出生长下降，这反映在生长指数的下降上。提取物诱导了不同类型的发育异常，特别是不完全蜕皮、多余龄、成虫和翅膀变形的成虫。在某些情况下，蜕皮不会脱离成虫的身体，对进食、行走和交配造成障碍。提取物对若虫发育的影响也是剂量依赖性的。5%及以上浓度处理，正常成人不能发育；在用 2.5% 至 0.1% 的提取物处理的若虫中报告了各种形态和发育异常。C. roseus 的己烷叶提取物的 GC-MS 分析表明存在倍半萜烯，包括香叶香叶醇和许多有毒化学物质。C. roseus 提取物的这些植物成分除了具有杀灭作用外，还表现出损害 D. koenigii 终生健康的保幼激素模拟活性。因此，来自 C. roseus 的植物有可能用作害虫管理的替代方法。