Life History, Larval and Pupal Morphology of Neoplinthus tigratus porculus (Fabricius, 1801) (Coleoptera: Curculionidae: Molytinae) Associated with Hop

The immature stages and biology of Neoplinthus tigratus porculus (Fabricius, 1801) (Coleoptera: Curculionidae: Molytinae) associated with common hop (Humulus lupulus L.) are described for the first time. Biological observations show that the species develops mainly within the root collar and roots of Humulus lupulus, where larvae feed internally and older instars overwinter. Infested plants are characterized by swollen and weakened roots, often containing multiple larvae. The species should be considered a potential pest of common hop, an economically important crop; however, the current observations indicate that its populations are generally very low, consistent with the status of several related Molytinae and Cleonini taxa, which are predominantly regarded as rare or locally occurring under contemporary agricultural conditions. Nevertheless, changes in agroecosystem management may significantly alter its abundance, as documented in other weevil taxa, where reductions in plant protection measures have led to local pest outbreak. The morphology and diagnostic characters of mature larvae and pupae are documented and compared with related Molytinae and selected Cleonini (Lixinae). The mature larva generally fits the diagnostic characters of Molytinae larvae but differs in several traits, particularly the very short endocranial line and the relative length of frontal setae (fs1–5), with fs4 distinctly shorter than fs5.