A Review of Chemically Based Communication in Miridae, with a Focus on Two Sympatric Species of Eccritotarsus

Abstract This report is a review of pertinent scientific literature on the chemical communication of the Miridae (Order Hemiptera; Suborder Heteroptera), with a focus on the sympatric species Eccritotarsus catarinensis Carvhalho and Eccritotarsus eichhorniae Henry. Both species have been deployed as biological control agents of water hyacinth, Pontederia (Eichhornia) crassipes (Martius) Solms-Laubach, in over 30 sites in South Africa. Our aim in this review was to gather and assimilate information on the chemical communication and chemical ecology of mirids, with an ultimate goal of enhancing the effectiveness of biological control agents of water hyacinth, particularly E. catarinensis and E. eichhorniae. Many hemipterans have highly developed metathoracic scent glands (MTGs), Brindley's glands, and secretory setae that store and emit chemicals that may act as allomones, kairomones, or pheromones. The preponderance of the available literature dealt with sex pheromones. Hexyl butyrate, (E)-4-oxo-2-hexenal, and (E)-2-hexenyl butyrate are reported to be sex pheromones in many mirids: for example, Adelphocoris fasciaticollis Reuter, Apolygus spinolae Meyer-Dür, Liocoris tripustulatus F., Lygocoris pabulinus L., several Lygus spp. (Lygus hesperus Knight, Lygus lineolaris Beauvois, Lygus elisus van Duzee, Lygus pratensis L., and Lygus rugulipennis Poppius), and Stenotus rubrovittatus Matsumura. Hexyl butyrate is the most prevalent sex pheromone in Miridae, while (E)-4-oxo-2-hexenal is the most prevalent sex pheromone in Heteroptera. Both pheromones co-occur in some species and exhibit many functionalities. The constancy of sex pheromones linked to behavioral patterns in Miridae suggest a punctuated equilibrium pattern of evolution (dating back to the Triassic), similar to morphological characters of many insects.