Zeljko Tomanovic

Vitex agnus castus and Euphorbia characias ssp. wulfenii as Reservoirs of Aphid Parasitoids (HymenopterA: Braconidae: Aphidiinae)

Abstract The role of the self-sown shrubs Vitex agnus castus and Euphorbia characias ssp. wulfenii as reservoirs of aphid parasitoids was investigated. In field studies, V. a. castus grew adjacent to an orchard of Citrus sinensis and E. characias ssp. wulfenii adjacent to an orchard of Prunus dulcis. The relative abundance of the parasitoids of Aphis viticis Ferrari on V. a. castus, Toxoptera aurantii (Boyer de Fonscolombe) on C. sinensis, Aphis euphorbiae Kaltenbach on E. characias ssp. wulfenii and Brachycaudus amygdalinus (Schouteden) on P. dulcis in various parts of Greece was assessed during 1996-2005. Aphidius colemani Viereck predominated on A. viticis and T. aurantii in all sampling cases. In contrast, Ephedrus persicae Froggatt was the dominant species parasitizing A. euphorbiae on E. characias ssp. wulfenii and B. amygdalinus on P. dulcis. Furthermore, to illustrate the agro-ecosystem relationships through the reservoirs, we present the distribution and host range patterns of parasitoids associated with aphids on V. a. castus and Euphorbia spp. in southeastern Europe. A key for the identification of aphid parasitoids on V. a. castus and Euphorbia spp. is provided.

Evaluation of three molecular markers for identification of European primary parasitoids of cereal aphids and their hyperparasitoids

Aphids are major pests of cereal crops and a suite of hymenopteran primary parasitoids play an important role in regulating their populations. However, hyperparasitoids may disrupt the biocontrol services provided by primary parasitoids. As such, understanding cereal aphid-primary parasitoid-hyperparasitoid interactions is vital for a reliable parasitoid-based control of cereal aphids. For this, the ability to identify the different primary and hyperparasitoid species is necessary. Unfortunately, this is often difficult due to a lack of morphologically diagnostic features. DNA sequence-based species identification of parasitoids can overcome these hurdles. However, comprehensive DNA sequence information is lacking for many of these groups, particularly for hyperparasitoids. Here we evaluate three genes [cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S) and 18S ribosomal RNA (18S)] for their suitability to identify 24 species of primary parasitoids and 16 species of hyperparasitoids associated with European cereal aphids. To identify aphelinid primary parasitoid species and hyperparasitoids, we found 16S to be more suitable compared to COI sequences. In contrast, the Aphidiinae are best identified using COI due to better species-level resolution and a more comprehensive DNA sequence database compared to 16S. The 18S gene was better suited for group-specific identification of parasitoids, but did not provide resolution at the species level. Our results provide a DNA sequence database for cereal aphid primary parasitoids and their associated hyperparasitoids in Central Europe, which will allow further improvement of our understanding of cereal aphid-primary parasitoid-hyperparasitoid interactions in relation to aphid biological control.

An effective molecular approach for assessing cereal aphid-parasitoid-endosymbiont networks

Molecular approaches are increasingly being used to analyse host-parasitoid food webs as they overcome several hurdles inherent to conventional approaches. However, such studies have focused primarily on the detection and identification of aphids and their aphidiid primary parasitoids, largely ignoring primary parasitoid-hyperparasitoid interactions or limiting these to a few common species within a small geographical area. Furthermore, the detection of bacterial secondary endosymbionts has not been considered in such assays despite the fact that endosymbionts may alter aphid-parasitoid interactions, as they can confer protection against parasitoids. Here we present a novel two-step multiplex PCR (MP-PCR) protocol to assess cereal aphid-primary parasitoid-hyperparasitoid-endosymbiont interactions. The first step of the assay allows detection of parasitoid DNA at a general level (24 primary and 16 hyperparasitoid species) as well as the species-specific detection of endosymbionts (3 species) and cereal aphids (3 species). The second step of the MP-PCR assay targets seven primary and six hyperparasitoid species that commonly occur in Central Europe. Additional parasitoid species not covered by the second-step of the assay can be identified via sequencing 16S rRNA amplicons generated in the first step of the assay. The approach presented here provides an efficient, highly sensitive, and cost-effective (~consumable costs of 1.3 € per sample) tool for assessing cereal aphid-parasitoid-endosymbiont interactions.

Aphidiinae (Hymenoptera, Braconidae) aphid parasitoids of Malta: review and key to species

This paper brings an annotated list of the 16 aphid parasitoids detected up to 2015 in Malta. All the species were reared from identified aphid-plant associations. An illustrated key to the identification of the recorded species from Malta is provided. Taxonomy and peculiarities of the individual taxa are discussed and research outlines are also presented. Two species, Aphidius absinthii and Trioxys pallidus are newly recorded for the Maltese fauna, in association with Uroleucon inulae and Hoplocallis picta, respectively. The first host association has never been reported so far. The documented aphid fauna of the Maltese Islands indicates the probable existence of other species of aphid parasitoids that may be present in the archipelago, especially those already known in nearby Mediterranean territories.