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Interactions between host plant quality and non‐consumptive predator effects on oviposition and larval behaviour of <i>Plutella xylostella</i> (Lepidoptera: Plutellidae)

Abstract The presence of predators can induce non‐consumptive effects on prey that result in subsequent changes to prey behaviour and defence. We investigate the interaction between top‐down non‐consumptive effects of various stages of the predator Coccinella septempunctata L.(Coleoptera: Coccinellidae) (larvae and adult) and bottom‐up effects of host nutrition on Plutella xylostella (L.) (Lepidoptera: Plutellidae) oviposition and larval host choice. We also compare the effect of presence of intact predators, predators without mandibles, confined predators and a no predator control treatment on P. xylostella larval growth, survival and herbivory. Host plant nutrition influenced the host choice of adult female P. xylostella; no interaction was observed between bottom‐up host plant nutrition and the presence of C. septempunctata adults or larvae on oviposition or larval host choice by P. xylostella. Predator presence impacted larval feeding and weight gain. The presence of free‐moving C. septempunctata adults without mandibles that could not predate P. xylostella reduced mean leaf consumption by P. xylostella larvae to 1.88 ± 0.21 cm2 and reduced weight gain to 2.12 ± 0.16 mg. Despite differences in leaf damage and larval weight gain, survival remained consistent across the non‐consumptive treatments. Intact C. septempunctata larvae reduced leaf damage and subsequent P. xylostella larval weight gain. The presence of larval predators across the non‐consumptive treatments, however, had no effect on feeding damage or weight gain. Results of our investigation indicate that C. septempunctata causes some non‐consumptive effects on P. xylostella that depend on predator life stage, level of confinement and prey life stage. It is likely that P. xylostella responds to multi‐modal cues in predator detection.

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Tracing the origin of the alien pest <i>Cydia pomonella</i> in <scp>Algeria</scp> through a worldwide comparison of the species’ <scp>DNA</scp> barcodes

Abstract DNA barcodes (i.e., gene sequences used as identifiers for species identification) constitute a very useful tool in invasive pest research. Using them, we studied, for the first time, the origin and population structure of the alien Cydia pomonella in Africa, a major apple pest. We sequenced a fragment of the mitochondrial gene Cytochrome c oxidase subunit I (COI) from C. pomonella caterpillars collected in northern Algeria and compared them with DNA barcodes from the rest of the world available at public repositories. The phylogeny built upon that COI database supports the European origin of the species: haplotypes at the base of the phylogeny were registered in this continent. In Algeria, the results suggest that this pest could have been introduced from Europe, with two unique African mutations probably favoured by C. pomonella multivoltinism and large population sizes. Population genetic analyses at three Algerian localities showed neither structure nor founder effects. However, to confirm the underlying process of the observed population patterns, it is necessary to perform analyses using genes with higher mutation rates. Compared to higher resolution markers, mitochondrial DNA barcodes are still a cost‐effective tool for taxonomic determination of unknown specimens and, sometimes, may also allow a preliminary tracing of its origin. This is crucial to detect and stop the spread of invasive pests (i.e., borders). We encourage further studies including functional genes to assess whether any mutations are promoting C. pomonella adaptation to the Northern Africa environment.

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Have native insect pests associated with a native crop in <scp>Maine</scp> declined over the past three to five decades?

Abstract Lowbush blueberry is an important berry crop in Maine (USA), Quebec and the Maritime provinces of Canada. The other economically important crops in Maine are potato, dairy and organic mixed vegetable produce. Lowbush blueberry is a complex of 1–4 Vaccinium species, primarily dominated by Vaccinium angustifolium Aiton. All but one of the insect pest species in this crop system are native to the regions where it is managed in North America. Insect decline has been shown to be a recent global phenomenon although it has rarely been studied in agricultural ecosystems. Long‐term datasets of insect species abundances are a powerful tool for insect population trends. To determine if native insect pests have declined over the past several decades in Maine lowbush blueberry, we surveyed three native species. All surveys were conducted in commercial blueberry fields; although, none of the sample sites were sprayed with insecticides. Insect pest sampling comprised two surveys (1961–2014 and 1998–2017) conducted on the larval stage of the blueberry maggot fly (Rhagoletis mendax Curran), one survey (1981–2016) on the larval stage of the blueberry spanworm (Itame argillacearia (Packard)), and one survey (1983–2019) on the larval stage of the blueberry flea beetle (Altica sylvia Malloch). Based upon the analysis of our long‐term population‐level datasets, we found no evidence that insect decline has occurred in this native blueberry insect pest complex intimately associated with the lowbush blueberry, a native crop plant in North America, despite recent documentation of rapid climate change occurring in the lowbush blueberry production areas.

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Potential biodiversity maps of Geadephaga (Coleoptera) from subantarctic forests: Relating diversity patterns and conservation hotspots with forest integrity

Abstract Potential biodiversity maps (PBMs) allow the identification of areas with different potential for conservation, to support political decisions about the management and protection of biodiversity. As these maps are seldom constructed for inconspicuous species, we proposed to develop PBMs for species belonging to the Geadephaga (Coleoptera), which is a group of beetles that contributes as predators for pest suppression and other ecosystem services in forest ecosystems. Given that human activities are reducing forest integrity, we consider that it is crucial to recognize how diversity patterns of Geadephaga are related to degraded forests. We developed these maps for the Geadephaga associated with subantarctic forests considering diversity measures of species richness, specificity, and rarity to establish spatial relationships between each diversity measure and different levels of forest integrity, and to identify potential hotspots and suggest conservation priorities. Results showed a latitudinal pattern of decrease in scores on richness and specificity from north to south, but a patchy pattern of species rarity across the region. Outcomes also show that areas with high scores of diversity measures are overlapped with degraded forest, and that hotspots have a low spatial overlap between them. In this work, we provide for the first time regional PBMs at a relatively high spatial resolution of three different diversity measures for Geadephaga that inhabit subantarctic forest. These maps constitute tools that allow not only to recognize potential diversity patterns of these insects, but also to offer valuable information to be used in conservation decision‐making.

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