Effects of a synthetic juvenile hormone and some analogues on Ephestia spp. (Lepidoptera: Phycitidae)

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Abstract
SUMMARY: Depending on their stage of development, treatment of mature larvae of Ephestia kühniella with a synthetic juvenile hormone resulted in the production of super larvae (which invariably prolonged larval life) and larval‐pupal intermediates. When migrating last‐instar larvae were treated with the juvenile hormone analogues (JHA) ethyl‐3,7, n‐trimethyldodeca‐2,4‐dienoate (ZR512) and isopropyl ii‐methoxy‐3,7, ii‐trimethyldodeca‐2,4‐dienoate (ZR515), larval‐pupal intermediates and pupal mortality were induced. However, when applied topically, ZR515 appeared more effective than ZR512. Both analogues prevented adult emergence when topically applied to the migrating larvae at doses between 28–52 ng. One‐day‐old pupae were most susceptible while older individuals became less sensitive with age. When larvae pupated in corrugated cardboard rolls were treated with ZR512 those of both E. cautella and E. kiihniella failed to emerge. At an estimated dose of 179 ng cm‐2, ZR515 prevented 77‐6%E. cautella and 100%E. kühniella larvae from emerging as adults. The control of Ephestia by JHA treatment of the pupation sites is discussed.