Providing Alternative Hosts and Nectar to Aphid Parasitoids in a Plum Orchard to Determine Resource Complementarity and Distance Range Effect on Biological Control

There are many different practices that contribute to conservation biological control, but little is known about their complementarity. We tested the effects of providing food and alternative hosts to parasitoids by intercropping a plum orchard with companion plants. Oats and vetch were intercropped into the orchard either as single-species (oats or vetch) or two-species (oats and vetch combined) intercrops within an inter-row. The trophic resources provided by these intercrops were assessed, along with the incidences of aphids and their parasitoids in plum trees. We found up to ten alternative host species provided by oats and vetch, and extrafloral nectar was available from the vetch and mixed strips. An effect of intercrop type and distance to plum trees was observed on aphid incidence during one sampling period. Parasitism rates in exclusion cages were affected by intercrop type, reaching almost 60% close to the mixed intercrop. However, no general tendency was observed upon whether oats, vetch or their mixture was associated with a lower incidence of aphids. We found no evidence that providing effective sources of food and alternative hosts for parasitoids increased aphid mortality in this study. The context-dependent efficiency of intercropping is discussed.

A new genus and species of the aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) from the Eocene Sakhalinian amber

The new fossil genus and species, Sakhalinoctonus alexrasnitsyni Davidian, gen. et sp. nov., of hymenopteran parasitoids of aphids from the subfamily Aphidiinae (Braconidae) is described from the Middle Eocene Sakhalinian amber. This new genus is similar with the extinct Protacanthoides Mackauer, 1961 and Promonoctonia Starý, 1973 as well as with the extant Calaphidius Mackauer, 1961, Indaphidius Starý, 1979, Aclitus Foerster, 1862 and Archaphidus Starý & Sсhlinger, 1967, and differs from them by the small number of antennal segments, details of wing venation and propodeum areolation, the shape and pubescence of the ovipositor sheaths.

Assemblies of the genomes of parasitic wasps using meta-assembly and scaffolding with genetic linkage

Safe, effective biological-control introductions against invasive pests depend on narrowly host-specific natural enemies with the ability to adapt to a changing environment. As part of a project on the genetic architectures of these traits, we assembled and annotated the genomes of two aphid parasitoids, Aphelinus atriplicis and Aphelinus certus. We report here several assemblies of A. atriplicis made with Illumina and PacBio data, which we combined into a meta-assembly. We scaffolded the meta-assembly with markers from a genetic map of hybrids between A. atriplicis and A. certus. We used this genetic-linkage scaffolded (GLS) assembly of A. atriplicis to scaffold a de novo assembly of A. certus. The de novo assemblies of A. atriplicis differed in contiguity, and the meta-assembly of these assemblies was more contiguous than the best de novo assembly. Scaffolding with genetic-linkage data allowed chromosomal-level assembly of the A. atriplicis genome and scaffolding a de novo assembly of A. certus with this GLS assembly, greatly increased the contiguity of the A. certus assembly to the point where it was also at the chromosomal-level. However, completeness of the A. atriplicis assembly, as measured by % complete, single-copy BUSCO hymenopteran genes, varied little among de novo assemblies and was not increased by meta-assembly or genetic scaffolding. Furthermore, the greater contiguity of the meta-assembly and GLS assembly had little or no effect on the numbers of genes identified, the proportion with homologs or functional annotations. Increased contiguity of the A. certus assembly provided modest improvement in assembly completeness, as measured by % complete, single-copy BUSCO hymenopteran genes. The total genic sequence increased, and while the number of genes declined, gene length increased, which together suggest greater accuracy of gene models. More contiguous assemblies provide uses other than gene annotation, for example, identifying the genes associated with quantitative trait loci and understanding of chromosomal rearrangements associated with speciation.

Genome-Wide Identification of Neuropeptides and Their Receptors in an Aphid Endoparasitoid Wasp, Aphidius gifuensi

In insects, neuropeptides and their receptors not only play a critical role in insect physiology and behavior but also are the potential targets for novel pesticide discoveries. Aphidius gifuensis is one of the most important and widespread aphid parasitoids, and has been successfully used to control aphid. In the present work, we systematically identified neuropeptides and their receptors from the genome and head transcriptome of A. gifuensis. A total of 35 neuropeptide precursors and 49 corresponding receptors were identified. The phylogenetic analyses demonstrated that 35 of these receptors belong to family-A, four belong to family-B, two belong to leucine-rich repeat-containing GPCRs, four belong to receptor guanylyl cyclases, and four belong to receptor tyrosine kinases. Oral ingestion of imidacloprid significantly up-regulated five neuropeptide precursors and four receptors whereas three neuropeptide precursors and eight receptors were significantly down-regulated, which indicated that these neuropeptides and their receptors are potential targets of some commercial insecticides. The RT-qPCR results showed that dopamine receptor 1, dopamine receptor 2, octopamine receptor, allatostatin-A receptor, neuropeptides capa receptor, SIFamide receptor, FMRFamide receptor, tyramine receptor and short neuropeptide F predominantly were expressed in the head whilst the expression of ion transport peptide showed widespread distribution in various tissues. The high expression levels of these genes suggest their important roles in the central nervous system. Taken together, our study provides fundamental information that may further our understanding of neuropeptidergic signaling systems in the regulation of the physiology and behavior of solitary wasps. Furthermore, this information could also aid in the design and discovery of specific and environment-friendly insecticides.

A survey of aphid parasitoids and hyperparasitoids (Hymenoptera) on six crops in the Kurdistan Region of Iraq

In this study, we surveyed aphids and associated parasitoid wasps from six important crop species (wheat, sweet pepper, eggplant, broad bean, watermelon and sorghum), collected at 12 locations in the Kurdistan region of Iraq. A total of eight species of aphids were recorded which were parasitised by eleven species of primary parasitoids belonging to the families Braconidae and Aphelinidae. In addition, four species of hyperparasitoids (in families Encyrtidae, Figitidae, Pteromalidae and Signiphoridae) were recorded. Aphelinus albipodus (Hayat & Fatima, 1992), A. flaviventris (Kurdjumov, 1913), A. varipes (Förster, 1841) (Aphelinidae), Aphidius rhopalosiphi (De Stefani, 1902), A. uzbekistanicus (Luzhetzki, 1960), (Braconidae) and Alloxysta arcuata (Kieffer, 1902) (Figitidae) were recorded in Iraq for the first time. The results represent the first survey of these interactions in this region and form the basis for understanding crop-aphid-parasitoid-hyperparasitoid networks and for future biological control actions.

Taxonomy, distribution and host relationships of aphidiine wasps (Hymenoptera: Aphidiidae) parasitizing aphids (Hemiptera: Aphididae) in Australian grain production landscapes

Aphid parasitoids (Hymenoptera; Aphidiidae) were surveyed within grain production landscapes in Victoria, Australia between 2017 and 2018, as well as more sporadically nationwide between 2016 and 2019. In addition, aphidiine records were collated from insect depositories around Australia and online databases. The 5551 specimens recorded constituted a total of 23 species and seven genera. Diaeretiella rapae (M’Intosh) was the most common species, representing more than 70% of all aphidiines recorded. This species also showed a greater northerly geographic range than other aphidiines. During sampling between 2017 and 2019, aphidiines were reared from mummies to ascertain host-parasitoid relationships. Diaeretiella rapae was again the most commonly reared parasitoid, although aphidiine preference varied with aphid host and between states and territories. An illustrated dichotomous key to Australian aphidiines in grain production landscapes is provided for the 11 species sampled in our field surveys. This is the first comprehensive review of aphidiines sampled within Australia in over two decades. Knowledge about the diversity and distribution of these parasitoids is important for understanding their impact on current and future invasions of aphid species. In addition, understanding the interactions between grain aphids and their associated parasitoids will further support the inclusion of parasitoid wasps into integrated pest management (IPM) strategies.