Abstract
Antennal sensory units in nymphs and adults of the spotted Lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae), an economically important plant pest, are studied with scanning electron microscopy. Sensilla trichodea / chaetica type recognition is based on their external morphology and ratio of their size to diameter. The flagellum Bourgoin’s organ is a complex sensory unit with 2–3 internal sensilla coeloconica. During nymphal stages, the sensory surface available for a chemoreceptive function particularly increases with the number and size of sensilla placodea on the antennal pedicel. From first to fourth instar and to adult males and females, plate organ sensory surface is estimated to increase respectively by 33x, 68x and 125x (= 2.72 mm2 and 5.02 mm2 respectively for males and females). The most important increase (5x) occurs between second and third instar. In parallel, a distinctive pair of plate organs on the flagellum decreases in size from first to third instar, and disappears. Sexual dimorphism occurs in sensilla placodea in adults. Diversity, disparity and evolution of nymphal sensilla, and their sexual dimorphism in adults are discussed in the context of the species and planthopper behaviour.
Highlights
The Spotted Lanternfly Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae) is a planthopper used in traditional Chinese medicine since 1100 [1]
The basal bulb is inserted basally in a socket on the apex of the pedicel. It presents a subapical opening encircled by concentrically arranged cuticular denticules (CD) (Figs 2A, 2B, 3A, 3C, 4B and 5B) indicating the location of the internal Bourgoin sensory organ (BO), which is flanked by the long arista, sharply ending apically (Figs 1, 2A, 2B, 3A, 3C, 5E, 4A, 4B, 5A, 5B and 5D)
Assuming that the sensory functions of these sensilla remain identical during the different life stages, the results suggest various hypotheses: 1. The progressive increase of the pedicel plate organ number during nymphal stages and the greater than 100% increase of the functional sensory surface in adults, suggest that the olfactory function is progressively installed in nymph and optimally reached in the adult stage only (Fig 12)
Summary
The Spotted Lanternfly Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae) is a planthopper used in traditional Chinese medicine since 1100 [1]. It has become an economically important agricultural Ailanthus), phloem feeding on the phloem of a wide range of host plants [2,3,4] and causing serious wilting, even death, of those host plants. L. delicatula was originally described from China, India (Assam, Bangladesh) and Japan [5], but it has been considered as introduced to Korea [6] and Vietnam [7]. Economic damage by the species in these countries is increasing annually, especially in Korea [1, 2, 8, 9]. In 2014, it was first recorded from eastern Pennsylvania, USA [4], where it was collected in large
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