Articles
Species composition of the egg parasitoids of bugs in hazelnut orchards in northwestern Italy
Article number
1379_59
Pages
409 – 416
Language
English
Abstract
Bugs have become the major pests of hazelnut in many areas worldwide.
In northwestern Italy, the most harmful species are Gonocerus acuteangulatus (Hemiptera: Coreidae) and Palomena prasina (Hem.: Pentatomidae), to which the invasive Halyomorpha halys (Hem.: Pentatomidae) has recently been added.
Whereas chemical control is difficult to apply and not always successful, great attention has been paid to natural enemies, especially egg parasitoids, as possible candidates as biological control agents (BCAs). Therefore, research was carried out to: 1) assess the species composition and richness of egg parasitoids in hazelnut orchards, and 2) evaluate the efficiency of the indigenous species as BCAs in a biological control strategy through augmentative releases.
Surveys were carried out in hazelnut orchards in Piedmont (northwestern Italy) to sample eggs of H. halys, P. prasina, and G. acuteangulatus as well as other bug species, such as Arma custos, Carpocoris sp., Dolycoris baccarum, Holcostethus sp., Nezara viridula, Pentatoma rufipes, Piezodorus lituratus, Rhaphigaster nebulosa (Hem.: Pentatomidae), from 2016 to 2021. Field collected eggs were reared in the laboratory until bug nymph or parasitoid adult emergence.
Among the indigenous species, Anastatus bifasciatus (Hymenoptera: Eupelmidae) was the most common egg parasitoid followed by Telenomus sp1, Te. turesis, Trissolcus belenus, Tr. cultratus, and by the two exotic species Tr. japonicus and Tr. mitsukurii (Hymenoptera: Scelionidae), since they were first recorded in northwestern Italy in 2018 and 2019, respectively.
Because of its presence in all sites and years, A. bifasciatus was tested as a BCA in hazelnut orchards, through augmentative releases in 2019. Although it was always found after the releases, the parasitism rate was not enough to control bug populations, especially those of H. halys. Further investigations are needed in the coming years to assess the interactions between native and exotic egg parasitoids, and their effectiveness in controlling bug populations.
In northwestern Italy, the most harmful species are Gonocerus acuteangulatus (Hemiptera: Coreidae) and Palomena prasina (Hem.: Pentatomidae), to which the invasive Halyomorpha halys (Hem.: Pentatomidae) has recently been added.
Whereas chemical control is difficult to apply and not always successful, great attention has been paid to natural enemies, especially egg parasitoids, as possible candidates as biological control agents (BCAs). Therefore, research was carried out to: 1) assess the species composition and richness of egg parasitoids in hazelnut orchards, and 2) evaluate the efficiency of the indigenous species as BCAs in a biological control strategy through augmentative releases.
Surveys were carried out in hazelnut orchards in Piedmont (northwestern Italy) to sample eggs of H. halys, P. prasina, and G. acuteangulatus as well as other bug species, such as Arma custos, Carpocoris sp., Dolycoris baccarum, Holcostethus sp., Nezara viridula, Pentatoma rufipes, Piezodorus lituratus, Rhaphigaster nebulosa (Hem.: Pentatomidae), from 2016 to 2021. Field collected eggs were reared in the laboratory until bug nymph or parasitoid adult emergence.
Among the indigenous species, Anastatus bifasciatus (Hymenoptera: Eupelmidae) was the most common egg parasitoid followed by Telenomus sp1, Te. turesis, Trissolcus belenus, Tr. cultratus, and by the two exotic species Tr. japonicus and Tr. mitsukurii (Hymenoptera: Scelionidae), since they were first recorded in northwestern Italy in 2018 and 2019, respectively.
Because of its presence in all sites and years, A. bifasciatus was tested as a BCA in hazelnut orchards, through augmentative releases in 2019. Although it was always found after the releases, the parasitism rate was not enough to control bug populations, especially those of H. halys. Further investigations are needed in the coming years to assess the interactions between native and exotic egg parasitoids, and their effectiveness in controlling bug populations.
Publication
Authors
F. Tortorici, S.T. Moraglio, M.G. Pansa, S. Scovero, S. Visentin, L. Tavella
Keywords
Anastatus bifasciatus, Scelionidae, Halyomorpha halys, Palomena prasina, host-parasitoid interaction, augmentative release
Groups involved
Online Articles (78)