The remarkably low leaf-selectivity prior to oviposition in the moth-pest Cameraria ohridella is not unique to this species within the genus Cameraria

Summary. — Cameraria ohridella, a recent leaf-mining invader of the horse-chestnut tree Aesculus hippocastanum, likely persists as a strong pest with unusually high levels of incidence. For example, among Cameraria moths, C. ohridella ordinarily features more than hundred times denser upon Aesculus leaflets than C. gr. guttifinitella is upon leaves of Quercus emoryi. There is general agreement to consider that the singular success of C. ohridella in mining Aesculus leaves mainly results from deficient top-down control, especially extremely low level of parasitoids efficiency. Another remarkable aspect of C. ohridella outbreaks however is the very high level of leaves acceptance (low selectivity) of females prior to egg-laying, which may often rise up near to 100 %. Would this low bottom-up control also feature (or not) as a specificity of this species within the genus Cameraria ? Using an appropriate indirect method, it is shown that the proportions of “ acceptable” leaves by ovipositing females are substantially similar (and high) in both Cameraria species (96 % and 78 % for Cameraria ohridella and C. gr. guttifinitella respectively), in spite of the dramatically different proportions of “ accepted” (= actually oviposited) leaves (89 % and 2 % respectively). In turn, this would contribute to make still more relevant the currently oriented focus upon top-down regulation as one of the major lever for a better control of Cameraria ohridella.