Invasive Stink Bug Halyomorpha Halys Research Articles

Interspecific competition between Trissolcus japonicus and Trissolcus mitsukurii, two promising candidates for biocontrol of Halyomorpha halys

The invasive stink bug Halyomorpha halys, native to east Asia, is a severe agricultural pest of worldwide importance and biocontrol is a promising method for its long-term management. The two Asian egg parasitoids Trissolcus japonicus and Trissolcus mitsukurii are considered to be effective candidates as biological control agents. These species can co-occur in the same habitats and interspecific competition for hosts could therefore have an important role in natural control. We assessed the foraging behavior and the progeny production of both species under laboratory conditions with three different interspecific competition scenarios. With indirect competition, H. halys egg masses previously parasitized by the female of one species were offered to the competitor females after 0, 3, 5, or 7 days. With direct extrinsic competition, females of each species were tested in arenas either when introduced simultaneously (synchronous release) or when half of the host egg mass had already been parasitized by the other species (asynchronous release). Both Trissolcus species were able to parasitize host eggs already parasitized by the other species, although the progeny production always favored the species that arrived first on the host egg mass. However, in the synchronous releases scenario, T. mitsukurii displayed more aggressive behavior and spent more time defending the host egg mass than T. japonicus, resulting in a higher progeny production. Our results showed that multiparasitism among T. japonicus and T. mitsukurii, at least under laboratory conditions, resulted in a general waste of searching time, energy, eggs laid, and a lower reproductive potential by the second-arriving species on the host egg mass.

Physiological host range of Trissolcus mitsukurii, a candidate biological control agent of Halyomorpha halys in Europe

The invasive stink bug Halyomorpha halys, native to East Asia, is a severe agricultural pest of worldwide importance, and chemical insecticides are largely sprayed for its control. Negative impact and failures of chemical pest management led to consider classical biological control as one of the most promising methods in a long-term perspective. The Asian egg parasitoid Trissolcus japonicus is the main candidate biocontrol agent of H. halys, but more recently a second species, Trissolcus mitsukurii, which shares the area of origin with H. halys, has drawn special attention after adventive populations were found in Europe. Despite its recent detection, intentional release or redistribution are bound to approval of national petitions, which requires detailed risk analyses. With the aim of providing a contribution for the future development of a risk assessment for release purposes, here we present the first study on the physiological (fundamental) host range of T. mitsukurii in Europe. Tests conducted on different hemipterans common to Southern Europe, using three different experimental designs, revealed a oligophagous host range, limited to Pentatomoidea and comparable with the host range displayed by T. japonicus under similar laboratory conditions. In addition to its coevolved host H. halys, T. mitsukurii successfully parasitized the majority of tested pentatomid species and one scutellerid, although with highly variable emergence rates. Notably high parasitization rates were detected on H. halys, Acrosternum heegeri and Dolycoris baccarum. Host egg sizes positively affected parasitoid size and female egg load. Although T. mitsukurii might be a promising biological control agent of H. halys in Europe, further studies (e.g., chemical ecology, field parasitism) are needed for assessment of non-target risks.

The invasive stink bug Halyomorpha halys affects the reproductive success and the experience-mediated behavioural responses of the egg parasitoid Trissolcus basalis

Invasive species, because of their lack of co-evolutionary history with recipient communities, can act as “evolutionary traps” causing disconnects between natural enemy behavioural responses and the suitability of the invasive species as a prey/host resource. Invasion of exotic species in non-native environments may have several ecological effects, including consequences for the experience-mediated behavioural responses of indigenous foragers. Experience is usually thought to help resident species to buffer against negative impacts of new invasive species, including escaping from evolutionary traps. Here we hypothesized that the impact of foraging experience depends on whether an indigenous egg parasitoid can correctly assess the resource suitability of a new invasive species for offspring development. We showed that the invasive stink bug Halyomorpha halys acts as an evolutionary trap for the indigenous egg parasitoid Trissolcus basalis leading to unsuccessful development of ~ 95% of the eggs laid in this host species. In a mixed scenario in which the associated resident stink bug Nezara viridula co-occurs with the invasive H. halys, we showed that oviposition experience in the low quality invasive host induces in T. basalis similar responses to those of the associated host. These results suggest that foraging experience does not lead to avoidance of an evolutionary trap. We discuss parasitoid foraging experience and reproductive success in the light of the evolutionary trap framework with implication for biological control.

First record of Trissolcus basalis (Hymenoptera: Scelionidae) parasitizing Halyomorpha halys (Hemiptera: Pentatomidae) in the United States

BackgroundA parasitoid wasp, Trissolcusbasalis (Wollaston), was recorded parasitizing eggs of the invasive stink bug Halyomorphahalys (Stål) in the United States. This is the first record of this species parasitizing fresh and frozen eggs of H.halys in the United States.New informationFirst record of Trissolcusbasalis parasitizing Halyomorphahalys eggs in the United States.

New record of Trissolcus solocis (Hymenoptera: Scelionidae) parasitising Halyomorpha halys (Hemiptera: Pentatomidae) in the United States of America.

BackgroundA parasitoid wasp, Trissolcus solocis Johnson, was recorded parasitising eggs of the invasive stink bug Halyomorpha halys (Stål), in the United States. This is the first record of this species parasitising eggs of H. halys.New informationFirst record of Trissolcus solocis parasitising Halyomorpha halys eggs in the United States and first record of T. solocis in Alabama.

Vicia faba plants respond to oviposition by invasive Halyomorpha halys activating direct defences against offspring

The invasive stink bug Halyomorpha halys is established in many European and American agro-ecosystems, where it causes severe crop losses. Potential control measures might include enhancement of plant defences. When attacked by herbivorous insects that oviposit on it, the plant may respond by priming direct defences, which might affect the development of future brood. Halyomorpha halys attacks numerous plant species in the invaded areas. Here, we investigated whether Vicia faba plants challenged by H. halys females can impair the development of its offspring through the activation of induced direct defences. We measured the weight and dimension of nymphs that developed on oviposition-experienced plants after 7 and 17 days from hatching. Nymphs that developed on oviposition-experienced plants weighed less compared to those that developed either on control plants or on plants solely subjected to H. halys feeding, and third instars showed shorter dimensions (tibia length). In addition, when oviposition-experienced plants were attacked by nymphs, higher and more rapid expression of two jasmonic acid-dependent genes (cysteine proteinase inhibitor gene and NAI1) was detected, possibly due to a mechanism of priming. Increased expression of the salicylic acid-responsive PR1 gene was also detected in egg-experienced plants, although the response was delayed compared to JA-dependent genes. Our results suggest that V. faba plants recognize H. halys oviposition as a warning signal and pre-activate defences against future nymphal herbivory.

Susceptibility of Halyomorpha halys (Hemiptera: Pentatomidae) eggs to different life stages of three generalist predators

AbstractThe invasive stink bug Halyomorpha halys Stål (Hemiptera: Pentatomidae) has recently become established in Canada, but little information is available regarding the ability of natural enemies to attack this pest in its invaded range. We tested the capacity of several life stages of three generalist predators, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), Coleomegilla maculata De Geer (Coleoptera: Coccinellidae), and Podisus maculiventris (Say) (Hemiptera: Pentatomidae), to attack H. halys eggs. The relative susceptibility of H. halys eggs to predator attack was compared to P. maculiventris eggs. We found evidence for differential ability to consume H. halys and P. maculiventris eggs both among predator species and within species among life stages. The most H. halys eggs were consumed by late-instar C. carnea, while fewest were consumed by second-instar and adult C. maculata, and second-instar C. carnea. The susceptibility of H. halys eggs to predators was similar to that of P. maculiventris eggs, with only early-instar P. maculiventris nymphs consuming significantly less H. halys eggs than P. maculiventris eggs. Our results provide a baseline for further testing of generalist predators against H. halys and illustrate the potential importance of considering the breadth of ontogeny across which candidates are able to attack the invasive pest.