Host susceptibility to Gonipterus platensis (Coleoptera: Curculionidae) of Eucalyptus species

Abstract

• Key message: Gonipterus platensisis an important insect pest of eucalypt plantations. Despite biological control by the egg parasitoidAnaphes nitens, economic losses remain high in several areas outside its native range where susceptible eucalypt species are grown in commercial plantations. The susceptibility toG. platensisof 17Eucalyptusspecies was evaluated and possible alternatives for reforestation in high pest incidence areas were identified. • Context: Gonipterus platensis is an important pest of Eucalyptus worldwide. Despite biological control, it causes significant losses to Eucalyptus plantations in several areas, requiring alternative management options. • Aims: We analysed host preference of G. platensis towards 17 Eucalyptus species to identify less susceptible plant materials that could be used in areas of high pest incidence. • Methods: Feeding damage was assessed in field trials in three consecutive years. No-choice and choice tests were conducted with Eucalyptus species of contrasting susceptibility. • Results: Within subgenus Symphyomyrtus, all species from section Maidenaria were used by G. platensis for feeding. Within this section, E. globulus was always the preferred species, while E. nitens was the least preferred. Differences in susceptibility were less pronounced at high attack intensity by G. platensis. Eucalyptus saligna (section Latoangulatae) was the least preferred species among Symphyomyrtus. All species from subgenus Eucalyptus had low susceptibility to G. platensis, particularly E. regnans, which was never attacked under field conditions. The results were confirmed by choice and no-choice laboratory and semi-field tests. • Conclusion: Significant differences in susceptibility to G. platensis were found between the 17 Eucalyptus species tested, which could be explored for reforestation with less susceptible plant materials.