New Caledonia is among Earth's biodiversity hotspots, and we are far from knowing how many species it sustains. We applied DNA-based methods for quick biodiversity assessment of New Caledonian Arsipoda flea beetles, enhancing the discovery and description of new species. Mitochondrial DNA phylogenetic analysis (cox1, rrnS) for four out of five known neocaledonian taxa hints at the existence of additional species, and two are confirmed and described based on morphology: Arsipoda geographica Gómez-Zurita sp. nov. and Arsipoda rostrata Gómez-Zurita sp. nov. Timing this small radiation using standard insect mitochondrial substitution rates places its origin in the Miocene. A DNA-based approach to investigate potential food plants for these herbivorous insects reveals associations with Myrsinaceae and Ericaceae, which have not yet been found in New Caledonia, suggesting that this indirect methodology may help in discovering undetected flora. Traditional taxonomy and molecular approaches cooperate here, boosting our knowledge on species inventory and ecological interactions where it is most needed.

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International audienceWe provide an up-to-date catalogue of the Coccomorpha Rubsaamen, 1899 of New Caledonia based on studies of collected and curated specimens and on the literature. One hundred and eighteen species (118) in ten families have been recorded to date, in 70 genera. Five of the genera (7.2%) are endemic, belonging to Asterolecaniidae Berlese, 1898 (Oacoccus Williams, 2007), Eriococcidae Cockerell, 1899 (Chazeauana Matile-Ferrero, 1988, Choneochiton Hodgson, 2014) and Monophlebidae Maskell, 1880 (Insulococcus Bhatti, 1991, Tessarobelus Montrouzier, 1864). Twenty-nine (29) species are endemic to New Caledonia, giving a rate of endemism of 24.6%. Most of the species are apparently human-assisted introductions. We provide here first records from New Caledonia for ten (10) species: Aulacaspis rosarum Borchsenius, 1858; Chrysomphalus pinnulifer (Maskell, 1891); Diaspis echinocacti (Bouche, 1833); Fiorinia phantasma (Cockerell & Robinson, 1915); Labidaspis myersi Green, 1929; Palmicultor browni (Williams, 1960); Poliaspoides formosana (Takahashi, 1930); Pseudococcus gilbertensis Beardsley, 1966; Pseudococcus orchidicola Takahashi, 1939 and Rhizoecus cacticans (Hambleton, 1946). Despite two introduction attempts for the biological control of weedy cactus, Hypogeococcus festerianus (Lizer y Trelles, 1942) is still considered absent from New Caledonia. Literature records of five species are shown to be erroneous: Dactylopius tomentosus (Lamarck, 1801); Dysmicoccus cocotis (Maskell, 1890); Lindingaspis buxtoni (Laing, 1927); Nipaecoccus filamentosus (Cockerell, 1893) and Clavaspis herculeana (Cockerell & Hadden, in Doane & Hadden, 1909), which are therefore considered absent from New Caledonia

Thirty-three species of aphids are now established in New Caledonia. All species appear to have been introduced accidentally by human activity in the last century. Here, 17 aphid species are recorded for the first time: Aphis eugeniae, Aphis glycines, Aphis odinae, Aulacorthum solani, Brachycaudus helichrysi, Cerataphis orchidearum, Greenidea psidii, Hyperomyzus carduellinus, Hysteroneura setariae, Lipaphis pseudobrassicae, Micromyzus katoi, Myzus ornatus, Pentalonia caladii, Rhopalosiphum nymphaeae, Rhopalosiphum rufiabdominale, Schizaphis rotundiventris, and Tetraneura fusiformis. Thirteen more species are also more or less regularly intercepted at the borders through biosecurity surveys, without further establishment. This demonstrates that aphids represent a major biosecurity threat, including a threat as potential plant virus vectors. The reinforcement of biosecurity is a priority for such biodiversity hotspots, from the perspectives of both agriculture and the native environment. Prioritisation and promotion of local development of vegetable and fruit production, rather than their risky importation from abroad, is desirable. Such an approach also should be promoted and extended to other Pacific islands, which all share the lack of native aphid fauna and their associated plant disease vector risks.

Detection of pest infestations in fresh produce traded internationally could offer improved prospects for reducing the movement of unwanted pests. Because immature stages of some pests can be difficult to find visually, other cues such as herbivore-induced volatiles that can potentially be detected at the early stages of infestation are worth investigating. In this study, we artificially infested postharvested apples (Malus × domestica ‘Royal Gala’) with two economic apple pests, the specialist codling moth (CM, Cydia pomonella Linnaeus, Lepidoptera: Tortricidae) and the generalist Queensland fruit fly (QFF, Bactrocera tryoni, Froggatt, Diptera: Tephritidae) and collected volatile organic compounds (VOCs) over time (days 0, 6, and 14–15). In both infestation experiments, we found a strong and significant interaction between time and treatment. Apples infested with the QFF emitted lower total amounts of VOCs than uninfested apples, whereas apples infested with the CM released similar total amounts of VOCs. Apples infested with CM had increases in several hexyl and butyl esters, which were particularly noticeable after 15 d. In contrast, changes in ethyl esters were characteristics of QFF infestation and could be detected from day 6. Our multilevel and multivariate statistical analysis identified specific volatile biomarkers for each species at each sampling time that can be used to design a new tool for remote detection and surveillance of these invasive pests in harvested apples. Nevertheless, other information such as the cultivar as well as the storage condition needs to be taken into consideration to increase accuracy of future odorant-based sensors for pest identification.