Volatiles Mediating Parasitism of Euschistus conspersus and Halyomorpha halys Eggs by Telenomus podisi and Trissolcus erugatus

Abstract

This study identified chemicals found on the eggs of two stink bug species, one native to western North America, Euschistus conspersus, and an invasive species from Asia, Halyomorpha halys. The responses of two scelionid egg parasitoids, Trissolcus erugatus and Telenomus podisi, toward natural stink bug egg volatiles, and synthetic reconstructions of egg volatiles, were tested in bioassays. A compound, methyl (2E,4Z)-2,4-decadienoate, previously identified as the major component of the male-produced aggregation pheromone of E. conspersus, was the major volatile identified from extracts of E. conspersus eggs. In contrast, for H. halys, the sesquiterpenoids that compose the male-produced aggregation pheromone of this species were not detected on eggs, whereas the presence of hexadecanal, octadecanal, and eicosanal was detected. In laboratory olfactometer tests, both Tr. erugatus and Te. podisi females were attracted to extracts of E. conspersus eggs, and to synthetic methyl (2E,4Z)-2,4-decadienoate. However, female Tr. erugatus and Te. podisi wasps were repelled, both by extracts of H. halys eggs and by a blend of the aldehydes identified from H. halys eggs. A follow-up field study, using hexane-washed and intact E. conspersus as sentinel eggs, showed that the parasitoids Trissolcus erugatus and Gryon obesum emerged from these eggs. Sentinel hexane-washed eggs treated with 3 ng of methyl (2E,4Z)-2,4-decadienoate were parasitized more by these two species than were hexane-washed or unwashed eggs, whereas hexane-washed eggs treated with a comparable dose of the C16,18,20 aldehyde mixture were avoided by these parasitoids. In a further field experiment, Trissolcus basalis was the primary parasitoid found in sticky traps baited with methyl (2E,4Z)-2,4-decadienoate, indicating that this species was attracted to, but either did not oviposit or develop in the E. conspersus sentinel eggs in the previous experiment.

Kairomones fromEuschistus herosegg masses and their potential use forTelenomus podisiparasitism improvement

“…Semiochemicals related to location, recognition and acceptance could be a practical solution to attract and retain natural enemies in field areas where there are pest spots (Borges and Aldrich, 1994). For example, the main compound present on the pentatomid Nearctic species E. conspersus egg masses, methyl (2E,4Z )-2,4-decadienoate, the principal component of maleproduced aggregation pheromone was attractive to egg parasitoids in the field and act only as kairomone when available in low quantity (close to 1 and 0.1 mg total) reported by Tognon et al (2016). In the present study, we did not identify any E. heros pheromonal Figure 1.…”

“…substance on egg masses, as compared to E. conspersus by Tognon et al (2016). We may conclude that pheromonal compounds on eggs are species-specific as also observed for H. halys eggs which contain no pheromones, but have substances that inhibit parasitism by native scelionids in North America, T. podisi and T. erugatus (Tognon et al, 2016). Michereff et al (2016) also did not identify any of the three male-specific components of E. heros sex pheromone in egg extracts from conspecific females, but these extracts were equally attractive to T. podisi.…”

“…podisi (Michereff et al, 2016); Euschistus conspersus Uhler, Halyomorpha halys Stål/T. podisi, Trissolcus erugatus Johnson (Tognon et al, 2016). Bin et al (1993) was the starting point to Heteroptera/ Scelionidae egg volatiles interaction.…”

Vertical Sampling in Tree Canopies for Halyomorpha halys (Hemiptera: Pentatomidae) Life Stages and its Egg Parasitoid, Trissolcus japonicus (Hymenoptera: Scelionidae)

“…podisi on alfalfa than hackberry, and the reverse for Trissolcus euschisti Ashmead. It is unknown whether kairomonal cues associated with H. halys egg masses attract T. japonicus from some distance, but Tognon et al (2016) showed that two closely related species, Te. podisi and Trissolcus erugatus Johnson, were attracted to the egg adhesive of Euchistus conspersus Uhler.…”

Current Status on the Functional Characterization of Chemosensory Receptors of Cydia pomonella (Lepidoptera: Tortricidae)

“…Indeed, aside from emission by Bartlett pear, methyl ester was found in the head, thoraxes and fecal pellets of the bark beetle Pityogenes chalcographus (Coleoptera: Curculionidae; Birgersson et al, 1990). In addition, methyl ester was also found in emissions from stink bugs of the genus Euschistus (Heteroptera: Pentatomidae; Aldrich et al, 1991; Tognon et al, 2016). …”