Development of the gall wasps Ophelimus spp. and the parasitoid Closterocerus chamaeleon (Hymenoptera: Eulophidae) on different Eucalyptus species and hybrid clones

Abstract

Ophelimus spp. (Hymenoptera: Eulophidae) are gall-inducing wasps associated with Eucalyptus species that have recently expanded their distribution and caused increasing damage in commercial plantations. In Argentina, Ophelimus maskelli and Ophelimus mediterraneus have been recorded; however, information on their population dynamics remains scarce. The present study aimed to analyse the abundance and attack levels of Ophelimus spp. on different Eucalyptus species and hybrid clones, and to evaluate the parasitism of Closterocerus chamaeleon (Hymenoptera: Eulophidae) on these hosts. Monthly samplings were conducted from December 2022 to January 2024 at three sites in the Pampean region of Buenos Aires Province, Argentina. Ophelimus maskelli was recorded on hybrid clones and Eucalyptus tereticornis, maintaining relatively stable populations throughout the year and exhibiting high parasitism levels by C. chamaeleon (99–100%). In contrast, O. mediterraneus attacked E. viminalis, E. benthamii, E. dunnii and E. cinerea, showing marked temporal fluctuations and considerably lower and more variable parasitism levels (1–100%). These results could indicate effective natural control of O. maskelli by C. chamaeleon, whereas O. mediterraneus appears to partially escape biological regulation under field conditions.