Sensilla on Organs of Adults of the Pistachio-Seed Wasp Eurytoma plotnikovi (Hymenoptera: Eurytomidae)

Abstract

The pistachio-seed wasp, Eurytoma plotnikovi Nikol'skaya, is a major pest of the biomass energy tree Pistacia chinensis. Understanding its sensory system is vital for uncovering host location mechanisms, but information on its olfactory system is limited. This study investigated the morphology of sensilla on the bodies of female and male E. plotnikovi. We identified seven types of sensilla on their antennae: sensilla trichodea I (ST I), sensilla trichodea II (ST II), sensilla trichodea III (ST III), sensilla chaetica (SC), sensilla placodea, multiporous grooved peg sensilla, and finger-like sensilla. Most types of sensilla on male antennae are significantly longer than those on females. Sensilla basiconica I (SB I) was located among the ommatidia of the compound eyes, with males having longer SB I than females. The maxillary and labial palps contained SC and ST II, with males exhibiting longer ST II and SC in maxillary palps, while male labial palps had longer ST II but shorter SC than females. The forelegs had antennae cleaners, which were longer in males. Female forelegs had sensilla basiconica (SB II) and sensilla trichodea (ST IV), while males had ST I and lacked SB II. The abdomen of E. plotnikovi is elliptic and petal-like, with coeloconic sensilla symmetrically distributed. Females had ST II and ST III around the ovipositor, while males had ST I and ST II near the copulatory organ. Identifying the sensilla in E. plotnikovi enhances our comprehension of its sensory capabilities and host plant-seeking behavior.