Genus Trissolcus Research Articles

Interactions between egg parasitoids and predatory ants for the biocontrol of the invasive brown marmorated stink bug Halyomorpha halys

AbstractThe brown marmorated stink bug Halyomorpha halys is an Asian species that has become a major agricultural pest in North America and Europe. Ants from the genus Crematogaster are predators of H. halys nymphs in Asia, as well as in the Mediterranean, where known native predators are still few. At the same time, ants usually do not harm H. halys eggs, which are the target of the main biological control agents, the scelionid parasitoids of the genus Trissolcus. However, ants, as generalist predators and territorial organisms, may kill or displace a variety of other insects, potentially interfering with parasitoids and biological control programmes. We conducted laboratory experiments to investigate the interactions between the Mediterranean ant Crematogaster scutellaris and the parasitoids T. japonicus and T. mitsukurii, evaluating the possibility that the ants could damage the parasitized eggs, attack the parasitoids during emergence or interfere with the egg‐laying behaviour of female parasitoids. Our results demonstrate that C. scutellaris is not able to damage parasitized eggs and is not aggressive towards adult parasitoids at any stage. The presence of ants can slow down the parasitization rate in T. mitsukurii females in the smallest laboratory setups; however, this has not been observed in a more natural setting. We suggest that ants may play a complementary role together with egg‐parasitoids in the control of H. halys without interfering with each other.

Performance of two egg parasitoids of brown marmorated stink bug before and after cold storage.

Introduction: The genus Trissolcus includes a number of egg parasitoids that are known to contribute to the control of Halyomorpha halys. The number of progenies, particularly females, is important for the efficient mass rearing of species used in augmentative biological control programs. Cold storage is an important technique for extending the shelf life of natural enemies used in such programs. Methods: We assessed how fecundity, sex ratio, lifespan, and the number of hosts parasitized within 24h were affected by host density for T. japonicus and T. cultratus when offered fresh H. halys eggs and how these parameters were affected if adult parasitoids were first placed in cold storage (11°C in the dark) for 19weeks before being used for propagation. Results: The fecundity were 110.2 and 84.2 offspring emerged at 25°C, for parasitoids not placed in cold storage; among the offspring that emerged, 82.6% and 85.6% were female for T. japonicus and T. cultratus, respectively. If first placed in cold storage, T. japonicus and T. cultratus produced 35.1 and 24.6 offspring per female, respectively, although cold storage significantly extended the shelf life. The survival rates of parasitoids that were placed in cold storage were 90.3% and 81.3% for females, and 3.2% and 0.9% for males of T. japonicus and T. cultratus, respectively. The number of hosts parasitized within 24h was not shown to be density dependent, but it was significantly lower after cold storage. Discussion: This information can be used to estimate the likely production for augmented rearing colonies for use in biological control programs.

Efficacy of Kairomone Lures to Attract Parasitoids of Halyomorpha halys

In its native range, Halyomorpha halys (Stål) is suppressed by parasitoids in the genus Trissolcus (Hymenoptera: Scelionidae). Trissolcus native to Utah have demonstrated low parasitism of H. halys, while adventive Trissolcus japonicus (Ashmead) have shown parasitism of up to 20%. Custom rubber septa lures containing stink bug kairomones, n-tridecane (attractant), and (E)-2-decenal (repellent), at 100%, 90%, and 80% levels of attractant (10 mg load rate), were placed adjacent to sentinel H. halys egg masses in northern Utah field trials. Egg masses were evaluated for the presence and intensity (proportion of parasitized eggs) of parasitism. Parasitism by T. japonicus and T. euschisti (Ashmead) was low; however, the 100% lure showed double the parasitism of the control and more than three times that of the 90% and 80%. Two-way choice mesocosm trials in the laboratory evaluated previous lures and a lower load rate of 5 mg-100% attractant treatment. Lures of 10 mg at 100% and 80% were more attractive to T. japonicus than the control, while 5 mg at 100% and 10 mg at 90% showed no significant attraction. Our results support a proof-of-concept of rubber septa as release devices for kairomones to attract T. japonicus and provide a baseline for future field-based studies.

Predstavnici roda "Trissolcus" (Hymenoptera: Scelionidae) prirodni neprijatelji štetnih stenica (Hemiptera: Pentatomidae) i preliminarna istraživanja u Srbiji

Different types of polyphagous true bug pests are present in Serbia and countries in the region, many of which stand out as significant pests of agricultural crops. Among the harmful true bugs, the green vegetable bug, Nezara viridula Linnaeus, 1758 and the brown marble bug Halyomorpha halys Stål, 1855 (Hemiptera: Pentatomidae) are the species that currently attract attention the most, primarily because of their invasive and polyphagous nautre and ability to migrate rapidly from one crop to another. In many regions, where harmful bugs cause large economic losses, control strategies are primarily based on the application of chemicals. In addition to chemical control measures, biological control measures are increasingly present, which are based on the application of natural enemies of pests. Species from the genus Trissolcus (Hymenoptera: Scelionidae) show the best results in the biological control of polyphagous true bug. The species that has been commercially used for many years to control harmful Hemiptera is Trissolcus basalis Wollaston, 1958, which is one of the most important natural enemies of the green vegetable bug in the World. The species Trissolcus japonicus Ashmead, 1904 and Trissolcus mitsukurii Ashmead, 1904 have been identified as the predominant parasitoids of the brown marble bug and show great potential in the biological control of this harmful species. Representatives of the genus Trissolcus are also registered on the territory of Serbia, which opens the possibility of including native species of the genus Trissolcus in the strategies of biological control of true bug pests on the territory of Serbia and the region.

Add Germany to the List-Adventive Population of Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) Emerges in Germany.

Simple SummaryThe brown marmorated stink bug, Halyomorpha halys, is an invasive pest species of global economic importance. It has a very broad host range and causes severe damages in agricultural, horticultural, and fruit crops. Control measures, including available chemical and mechanical options, have often proved insufficient. Surveys of natural enemies in the newly invaded areas have also shown that natural biological control is generally too low to control H. halys populations in the long run. In its native Asian range, egg parasitoids in the genus Trissolcus play an important role in controlling H. halys. Since the mid-2010s, adventive populations of Trissolcus japonicus, a dominant egg parasitoid of H. halys in Asia with a narrow host range, have been reported from several countries with prior establishment of H. halys. Here, we report the first discovery of T. japonicus in Germany. This finding corroborates a northbound expansion of the range of T. japonicus in Europe, along with H. halys.The brown marmorated stink bug, Halyomorpha halys, is a polyphagous pest species of worldwide economic importance. Since the mid-1990s, it has invaded and become established in various countries outside its native Asian range. In the newly invaded areas, biological control by native natural enemies has been shown to be insufficient in the long-term control of this severe pest. Adventive populations of Trissolcus japonicus, an important biological control agent of H. halys in Asia, have been reported from North America and some European countries since the mid-2010s. This egg parasitoid species seems to follow in the wake of the establishment of H. halys populations outside their native Asian range. Here, we report the first discovery of an adventive population of T. japonicus in Germany. In 2020, adult T. japonicus were recovered from parasitized H. halys egg masses (naturally laid and sentinel egg masses) and collected in ruderal areas using an insect suction sampler. The arrival of T. japonicus in Germany, unintentional through pathways yet unknown, corroborates a northbound expansion of its range within Europe. Further field surveys will show the extent of its dispersal and establishment capacities within this new distribution area.

Biological characteristics of Trissolcus urichi (Crawford) (Hymenoptera: Scelionidae) on Euschistus heros (Fabricius) and Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae) Eggs

Species of the genus Trissolcus are effective as egg parasitoids of Euschistus heros and can potentially be used in a multispecies pest management approach. However, in order to successfully use those biocontrol agents in the field, previous detailed knowledge about their life history are necessary. Therefore, we evaluate some biological characteristics of Trissolcus urichi on Euschistus heros and Dichelops melacanthus eggs. Three independent experiments were performed: (1) T. urichi host preference between E. heros and D. melacanthus eggs. (2) T. urichi eggs-adult period (days), number of parasitized eggs in 24 h, emergence rate (%) and sex ratio of the parasitoid in E. heros and D. melacanthus eggs. (3) Morphometric characteristics of T. urichi grown on E. heros and D. melacanthus eggs. Trissolcus urichi preferred to parasitize E. heros eggs, exhibiting a higher number of parasitized eggs, higher rate of emergence (%) and faster development, as well as producing progeny of larger size than the parasitoids emerged from eggs of D. melacanthus in relation to body length, wing length and width. Thus, it can be concluded that T. urichi had better performance on E. heros eggs, although the parasitoid had also acceptable parasitism capacity and development in D. melacanthus eggs.

Karyotypes of three species of the genus Trissolcus Ashmead, 1893 (Hymenoptera: Scelionidae)

Karyotypes of three species of the genus Trissolcus Ashmead, 1893 (Hymenoptera: Scelionidae)

Biological control of sentinel egg masses of the exotic invasive stink bug Halyomorpha halys (Stål) in Mid-Atlantic USA ornamental landscapes

Biological invasions have far reaching effects on native plant and arthropod communities. This study evaluated the effect of natural enemies on eggs of the exotic invasive brown marmorated stink bug Halyomorpha halys (Stål) in experimental plots comprising species pairs of 16 ornamental trees and shrub genera from either Eurasia or North America and in wooded areas adjacent to the plots. Sentinel egg masses were placed on leaves of Acer, Cercis, Hydrangea, and Prunus in the plots and in seven genera of trees and shrubs in adjacent woods. Overall, rates of parasitism and predation in experimental plots were low, accounting for only 3.8% and 4.4% of egg mortality, respectively. There were no significant differences in parasitism and predation rates between native or exotic plots or between plants of different genera. In 2015, predation was significantly higher in the experimental plots than in the wooded sites, but parasitism was significantly higher in the wooded sites. In the experimental plots, seven native and one exotic parasitoid species attacked sentinel egg masses. Six native parasitoid species attacked sentinel egg masses in the wooded sites. Parasitoids in the genus Trissolcus were more likely to attack egg masses in exotic plots than in native plots. There is no evidence that native natural enemies attacking eggs of the exotic BMSB were more prevalent in landscapes with native ornamental trees and shrubs than those with exotic trees and shrubs.

Egg-parasitoids of the genus Trissolcus (Hymenoptera, scelionidae, telenominae) from the Palaearctic region. The flavipes morphological group: 2. A key to the species of the flavipes group

An improved key to the Palaearctic species of the genus Trissolcus Ashmead (the flavipes morphological group) is provided.

Egg-parasitoids of the genus Trissolcus (Hymenoptera, Scelionidae, Telenominae) from the Palaearctic fauna (the flavipes morphological group). 1. New species of the genus Trissolcus

The Trissolcus flavipes species group is revised. A key to the species of this group is provided. In addition to the diagnostic characters, the localities are listed for each species. Eleven new species occurring in various Palaearctic areas are described. Some body structures are illustrated. The morphological characters of the new species are compared.

Three new species of Trissolcus ashmead (Hymenoptera: Platygastroidea: Scelionidae) from Bulgaria

Identification key of 20 species of the genus Trissolcus registered in Bulgaria is given. Three species, T. fuscus sp. n., T. simplex sp. n. and T. nigricans sp. n. are described as new for science.

Checklist of Iranian Trissolcus Ashmead (Hymenoptera: Platygastroidea: Scelionidae: Telenominae)

This paper summarises Iranian records of the genus Trissolcus Ashmead 1893 (Hymenoptera: Platygastroidea: Scelionidae). In total, 19 species are now known. One of these, Trissolcus crypticus Clarke, is a new record for Iran. In addition, the paper provides synonyms, hosts and distributional data for all the species.

Trissolcus radjabii n.sp. (Hymenoptera: Platygastridae), an egg parasitoid of the shield bug, Apodiphus amygdali (Heteroptera: Pentatomidae) and the sunn pest, Eurygaster integriceps (Heteroptera: Scutelleridae)

Kozlov and Kononova (1983) classified 53 Palearctic species of the genus Trissolcus Ashmead into five groups. The presence of the hyperoccipital carina, convex frons, absence of notauli, and elongate postmarginal vein (longer than the stigmal vein) in the fore wing are characteristics delimiting the gonopsidis-group. These species differ from the flavipes-group only in the lack of notauli. Kozlov and Kononova placed three species in the gonopsidis-group: T. mentha Kozlov and Lê, T. gonopsidis (Watanabe), and T. elasmuchae (Watanabe). In a taxonomic study of the Trissolcus species of Korea and Japan, Ryu and Hirashima (1984) reported three other species with characteristics of the gonopsidis-group: T. nigripedius (Nakagawa), T. itoi Ryu and T. yamagishi Ryu. Most of these species are known only from Japan or Korea. Trissolcus elasmuchae has been observed in Ukraine and Russia as well as Japan, and T. mentha is known only from Uzbekistan. Trissolcus antakyaensis Doganlar was described recently as an egg parasitoid of the pentatomid Rhaphigaster nebulosa (Poda) from Turkey (Doganlar 2001). It, too, fits within this gonopsidis- group. The New World species of Trissolcus were divided into three groups (Johnson 1984, 1985a, 1985b); the thyantae, basalis, and flavipes groups of Johnson are roughly equivalent to the simoni, semistriatus, and flavipes groups of Kozlov and Kononova respectively. No species of gonopsidis and oobius groups of Kozlov and Kononova have been reported in New World fauna.

A finely tuned strategy adopted by an egg parasitoid to exploit chemical traces from host adults

Scelionid egg parasitoids can obtain reliable information on the presence of host eggs by discriminating host gender on the basis of chemical footprints of their co-evolved hosts, with a strong preference for the footprint left by host females. Based on the concept of dietary specialization and infochemical use in natural enemies, it could be predicted that host gender discrimination in specialist species belonging to the genus Trissolcus is further tuned to specific cues from distinctive chemical traces left by host females as a consequence of copulation and/or oviposition. To test this hypothesis we used the system Murgantia histrionica - Trissolcus brochymenae. Our results showed that the females of the egg parasitoid search intensely on chemical traces left on the substrate by host females that had mated but had not yet laid host eggs compared with the chemical traces left by virgin or parous host females. This preference for mated females that had not yet laid host eggs was strictly related to the transfer of sperm and associated substances from males to females during copulation. The compounds that mediated the arrestment response of T. brochymenae females are part of the host cuticle, and those that play a role as gender-specific cues seemed to be present in the legs of the host adult. This result represents an interesting new piece of information regarding the exploitation of indirect host-related cues by egg parasitoids. It reveals the existence of a finely tuned strategy that allows the parasitoid to find newly laid host eggs, as chemical traces left by mated host females that have not yet laid eggs are strongly correlated with the moment of oviposition.

Stink Bug (Hemiptera: Pentatomidae) Egg Parasitism in Louisiana Soybeans

Stink bug egg parasitism rates were surveyed at several locations in southern Louisiana during 1983 and 1984. Eggs of Euschistus spp. were parasitized most heavily. Parasitism of eggs of Nezara viridula (L.), Euschistus spp., Acrosternum hilare (Say), Podisus maculiventris (Say), and Edessa bifida (Say) varied between sample years. All parasitoid species collected were in the family Scelionidae. Telenomus podisi Ashmead was the most prevalent parasitoid during both 1983 and 1984. Parasitism by Trissolcus basalis Wollaston was high in 1983 but declined sharply the following year when populations of its primary host, N. viridula, were low. Apparent host switching was noted for both T. podisi and T. basalis from their primary hosts Euschistus spp. and N. viridula, respectively, when densities of all host masses increased. Trissolcus edessae Fouts and Trissolcus euschisti Fouts were collected both years at levels substantially below those of T. podisi and T. basalis. Telenomus calvus Johnson, a phoretic egg parasitoid of P. maculiventris, and Telenomus cristatus Johnson were collected incidentally during 1983. Parasitism of single egg masses by two different scelionid species was observed in all pentatomid hosts except E. bifida. In every case except one, both a Trissolcus species and T. podisi were involved. In the lone exception, both species were in the genus Trissolcus. Multiparasitism of individual eggs was not observed in this study.

Taxonomic studies on the genus Trissolcus Ashmead of Japan and Korea (Hymenoptera, Scelionidae).

Taxonomic studies on the genus Trissolcus Ashmead of Japan and Korea (Hymenoptera, Scelionidae).

Taxonomic Studies on the Genus Trissolcus Ashmead of Japan and Korea (Hymenoptera, Scelionidae)

Taxonomic Studies on the Genus Trissolcus Ashmead of Japan and Korea (Hymenoptera, Scelionidae)

Two new species of the genus Trissolcus (Hymenoptera, Scelionidae) of the fauna of the USSR.

Two new species of the genus Trissolcus (Hymenoptera, Scelionidae) of the fauna of the USSR.

On the synonymy of two species of the genus Trissolcus Ashmead (Hymenoptera, Scelionidae).

On the synonymy of two species of the genus Trissolcus Ashmead (Hymenoptera, Scelionidae).