Catch me if you can: novel foraging behavior of an egg parasitoid, Gryon gonikopalense, against the stinkbug pest, Bagrada hilaris

Parasitism by Gryon aetherium (Hymenoptera: Scelionidae) on Bagrada hilaris (Hemiptera: Pentatomidae) eggs in northcentral California

“…Furthermore, the ability of G. aetherium to attack eggs in soil indicates that it co-evolved with B. hilaris because no other stink bugs are known to bury their eggs. Our results show that G. aetherium can consistently attack eggs in soil in the field, in line with its behavior in the laboratory (Tofangsazi et al 2020, Martel and Sforza 2021) and in the field (Hogg et al 2021). In fact, G. aetherium may preferentially search at ground level.…”

“…Although native parasitoids in California may use long-range cues from cruciferous weeds that are hosts of both B. hilaris and native stink bugs, they may not react to contact kairomones produced by B. hilaris . In contrast, G. aetherium was able to locate eggs buried beneath 2 mm of clean sand in the laboratory, suggesting that it responds to compounds emitted by the eggs themselves (Martel and Sforza 2021). Moreover, G. aetherium is able to dig through substrate to access the eggs (Martel and Sforza 2021), and native stink bug parasitoids in California are unlikely to have this ability.…”

“…In contrast, G. aetherium was able to locate eggs buried beneath 2 mm of clean sand in the laboratory, suggesting that it responds to compounds emitted by the eggs themselves (Martel and Sforza 2021). Moreover, G. aetherium is able to dig through substrate to access the eggs (Martel and Sforza 2021), and native stink bug parasitoids in California are unlikely to have this ability.…”

“…or O. mirus (Power et al 2020). Furthermore, it can search for and attack B. hilaris eggs in the soil (Tofangsazi et al 2020, Martel and Sforza 2021), whereas T. hyalinipennis either cannot or can with only low efficiency (Tofangsazi et al 2020). In a survey of California using sentinel B. hilaris eggs that were glued to cards and placed either on the ground or in plant foliage, about 90% of parasitism occurred in plant foliage (Hogg et al 2022), where all other stink bugs besides B. hilaris are likely to lay their eggs.…”

 Gryon aetherium Talamas (Hymenoptera, Scelionidae): Parasitoid of Bagrada hilaris (Burmeister) (Hemiptera, Pentatomidae) Adventive in Chile

“…Indeed, B. hilaris displays a specific oviposition behavior among stink bugs by laying part of its eggs in isolation and underground. Nonetheless, G. aetherium can detect buried eggs and overcome the physical barrier constituted by the soil (Martel and Sforza 2021). Other parasitoids of B. hilaris eggs, such as T. hyalinipennis (Hymenoptera, Scelionidae), may not be capable of this (Tofangsazi et al 2020).…”