Chestnut Leafminer Cameraria Ohridella Deschka Research Articles

Did the parasitoid Pnigalio mediterraneus (Hymenoptera: Eulophidae) track the invasion of the horse chestnut leafminer?

How communities of natural enemies, such as parasitoids, adapt to the range expansion of their hosts or the arrival of a novel invasive host is an important question in invasion biology. Do parasitoids track the expansion of their hosts from their shared native range? Do they locally adapt both behaviorally and physiologically to the arrival of a novel species by shifting hosts? Few studies have addressed those questions, yet they are important to develop efficient methods to manage invasive species. Here we focus on Pnigalio mediterraneus Ferriere and Delucchi (Hymenoptera: Eulophidae), an important parasitoid of two major agricultural and ornamental pests, the olive fruit fly Bactrocera oleae Rossi (Diptera: Tephritidae) and the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae). C. ohridella recently invaded Europe starting from the Southern Balkans, whereas B. oleae has been associated since the Quaternary with wild olives in the Mediterranean, where it largely spread after the domestication of cultivated olives. We used two markers, the ribosomal spacer ITS2 and the mitochondrial gene COI. Although the ITS2 dataset provided little variation and no phylogeographic signal, analysis of mtDNA of 188 individuals of P. mediterraneus from 54 European localities allowed us to identify 53 haplotypes. Both nucleotide and haplotype diversity were higher for Mediterranean samples, and from samples reared from B. oleae. The statistical parsimony network identified one haplotype as the most frequent, ancestral and mainly associated with C. ohridella. Our findings suggest that P. mediterraneus locally host switched to C. ohridella from other hosts in the Balkans and later tracked the horse chestnut leafminer invasion over Europe. Therefore both host-tracking and ecological sorting could explain the current distribution of P. mediterraneus haplotypes.

Possibilities of protection of the horse-chestnut Aesculus hippocastanum L. against the horse chestnut leaf-miner Cameraria ohridella Deschka et Dimic

Możliwości ochrony kasztanowca zwyczajnegoAesculus hippocastanumL. przed szrotówkiem kasztanowcowiaczkiemCameraria ohridellaDeschka et Dimic

Parasitic Ichneumonoidea on the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae) in Slovakia

Parasitic Hymenoptera from the suprafamily Ichneumonoidea attacking the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) were studied in southwest Slovakia during 2000 and 2001. The search for such species resulted in the determination of eight ichneumonid species, Gelis agilis (Fabricius), Itoplectis alternans (Gravenhorst), I. clavicornis (Thompson), I. maculator (Fabricius), Scambus annulatus (Kiss), S. brevicornis (Gravenhorst), Zatypota percontatoria (Muller), Adelognathus sp. and a braconid Colastes braconius Haliday. The most abundant species was S. annulatus. All these species recorded are polyphagous and often facultative hyperparasitoids, except C. braconius, which departs from this norm in not being hyperparasitic. The presence of more diversified native parasitoids and hyperparasitoids from the Ichneumonoidea predicate a slow successive adaptation of the parasitoid fauna to the invasive host, Cameraria ohridella.

Spatial patterns and infestation processes in the horse chestnut leafminer Cameraria ohridella: a tale of two cities

AbstractSpatial patterns of the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) population density was analysed in the cities of Bern and Brussels in order to explore its spatial population dynamics. The surveys were carried out in Bern in 1998 and 2000 and in Brussels in 2001 to assess population density in relation to local characteristics. In Brussels, population density was also measured using pheromone traps distributed over the city and collected twice per moth generation. A quantitative relationship was found between local population density (measured by pheromone traps and survey observations) and the amount of leaves left on the ground the previous fall. Several other factors were related to observed infestation levels: the occurrence of the pathogen Guignardia aesculi was inversely related to infestation by C. ohridella in Bern in 1998 and 2000, the number of horse chestnut trees within 800 m distance was positively related to infestation level in Bern in 2000, and the proportion of green areas within 100 m and the number of other horse chestnut trees within 2000 m were positively related to infestation levels in the 2001 Brussels survey. The pattern of infestation levels as a function of distance to potential population reservoirs suggested that C. ohridella re‐invades areas where overwintering leaves have been cleaned from refuge areas such as parks or urban forests. Our results indicate that the removal of leaves is a feasible first aid control measure to reduce moth population densities. However, leaf removal may not reduce moth densities when done improperly. In places where proper leaf removal is not feasible, other control measures are needed.