External morphology of antennal and rostral sensillae in four hemipteran insects and their possible role in host plant selection

Abstract

The sensory receptors on the antennal flagellar segments and on the rostral tip of four adult hemipteran insects were identified and compared using scanning electron microscopy in order to better understand the role of sensillae in the process of host plant selection and the structural adaptations of feeding organs for phytophagy. The species studied are Riptortus pedestris Fabricius (Alydidae), Elasmolomus sordidus (Fabricius) (Lygaeidae), Cyclopelta siccifolia Westwood (Pentatomidae) and Chrysocoris purpurea (Westwood) (Pentatomidae). Differences in the distribution and arrangement of sensory receptors in the hemipteran families were noted, especially in the shape of the antennal apices, which are of taxonomical significance. A large array of trichoid basiconic and coeloconic sensillae is distributed on the antennal surface. Distal antennal segments have more sensillae and more types of sensillae than the proximal segments, indicating their prominent role in host plant surface exploration. There is only a slight variation in the shape of the stylets owing to the similarity in feeding habits. The mandibular tips are straight and sharp and do not contain any hooks or barbs as in carnivorous species.