School of BioSciences - Research Publications

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    Scientists' warning on climate change and insects
    Harvey, JA ; Tougeron, K ; Gols, R ; Heinen, R ; Abarca, M ; Abram, PK ; Basset, Y ; Berg, M ; Boggs, C ; Brodeur, J ; Cardoso, P ; de Boer, JG ; De Snoo, GR ; Deacon, C ; Dell, JE ; Desneux, N ; Dillon, ME ; Duffy, GA ; Dyer, LA ; Ellers, J ; Espindola, A ; Fordyce, J ; Forister, ML ; Fukushima, C ; Gage, MJG ; Garcia-Robledo, C ; Gely, C ; Gobbi, M ; Hallmann, C ; Hance, T ; Harte, J ; Hochkirch, A ; Hof, C ; Hoffmann, AA ; Kingsolver, JG ; Lamarre, GPA ; Laurance, WF ; Lavandero, B ; Leather, SR ; Lehmann, P ; Le Lann, C ; Lopez-Uribe, MM ; Ma, C-S ; Ma, G ; Moiroux, J ; Monticelli, L ; Nice, C ; Ode, PJ ; Pincebourde, S ; Ripple, WJ ; Rowe, M ; Samways, MJ ; Sentis, A ; Shah, AA ; Stork, N ; Terblanche, JS ; Thakur, MP ; Thomas, MB ; Tylianakis, JM ; Van Baaren, J ; Van de Pol, M ; Van der Putten, WH ; Van Dyck, H ; Verberk, WCEP ; Wagner, DL ; Weisser, WW ; Wetzel, WC ; Woods, HA ; Wyckhuys, KAG ; Chown, SL (WILEY, 2023-02)
    Abstract Climate warming is considered to be among the most serious of anthropogenic stresses to the environment, because it not only has direct effects on biodiversity, but it also exacerbates the harmful effects of other human‐mediated threats. The associated consequences are potentially severe, particularly in terms of threats to species preservation, as well as in the preservation of an array of ecosystem services provided by biodiversity. Among the most affected groups of animals are insects—central components of many ecosystems—for which climate change has pervasive effects from individuals to communities. In this contribution to the scientists' warning series, we summarize the effect of the gradual global surface temperature increase on insects, in terms of physiology, behavior, phenology, distribution, and species interactions, as well as the effect of increased frequency and duration of extreme events such as hot and cold spells, fires, droughts, and floods on these parameters. We warn that, if no action is taken to better understand and reduce the action of climate change on insects, we will drastically reduce our ability to build a sustainable future based on healthy, functional ecosystems. We discuss perspectives on relevant ways to conserve insects in the face of climate change, and we offer several key recommendations on management approaches that can be adopted, on policies that should be pursued, and on the involvement of the general public in the protection effort.
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    How often are male mosquitoes attracted to humans?
    Paris, V ; Hardy, C ; Hoffmann, AA ; Ross, PA (The Royal Society, 2023-10)
    Many mosquito species live close to humans where females feed on human blood. While male mosquitoes do not feed on blood, it has long been recognized that males of some species can be attracted to human hosts. To investigate the frequency of male mosquito attraction to humans, we conducted a literature review and human-baited field trials, as well as laboratory experiments involving males and females of three common Aedes species. Our literature review indicated that male attraction to humans is limited to a small number of species, including Ae. aegypti and Ae. albopictus. In our human-baited field collections, only 4 out of 13 species captured included males. In laboratory experiments, we found that male Ae. notoscriptus and Ae. vigilax showed no attraction to humans, while male Ae. aegypti exhibited persistent attraction for up to 30 min. Both male and female Ae. aegypti displayed similar preferences for different human subjects, suggesting that male Ae. aegypti respond to similar cues as females. Additionally, we found that mosquito repellents applied to human skin effectively repelled male mosquitoes. These findings shed light on mosquito behaviour and have implications for mosquito control programmes, particularly those involving the release or monitoring of the male mosquito population.
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    Evaluation of In2Care mosquito stations for suppression of the Australian backyard mosquito, Aedes notoscriptus (Diptera: Culicidae)
    Paris, V ; Bell, N ; Schmidt, TL ; Endersby-Harshman, NM ; Hoffmann, AA ; Yee, D (OXFORD UNIV PRESS INC, 2023-09-12)
    Aedes notoscriptus (Skuse) is a container-inhabiting mosquito endemic to Australia that vectors arboviruses and is suspected to transmit Mycobacterium ulcerans, the cause of Buruli ulcer. We evaluated the effectiveness of the In2Care station, which suppresses mosquito populations via the entomopathogenic fungus, Beauveria bassiana, and the insect growth regulator pyriproxyfen, the latter of which is autodisseminated among larval habitats by contaminated mosquitoes. A field trial was conducted using 110 In2Care stations in a 50,000 m2 area and results were compared to 4 control areas that did not receive the treatment. Efficacy was evaluated by comparing egg counts and measuring larvicidal impact in surrounding breeding sites. Laboratory experiments validated the effect of B. bassiana on adult survival. Results of this field trial indicate that, 6 wk after the In2Care stations were deployed, treatment site ovitraps contained 43% fewer eggs than control site ovitraps, and 33% fewer eggs after 10 wk, suggesting that the In2Care station was able to reduce the egg density of Ae. notoscriptus. Population reduction remained evident for up to 3 wk after In2Care stations were removed. Treatment site ovitraps had significantly fewer Ae. notoscriptus eclosing than control site ovitraps, confirming the pyriproxyfen autodissemination feature of the stations. An average reduction of 50% in adult eclosion was achieved. Exposure to B. bassiana resulted in four-times higher mortality among adult mosquitoes. Additionally, using fresh In2Care nettings led to an 88% decrease in average survival compared to 4-wk-old nettings. The use of In2Care stations has potential for suppressing Ae. notoscriptus egg density.
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    Genomic databanks provide robust assessment of invasive mosquito movement pathways and cryptic establishment
    Schmidt, TL ; Endersby-Harshman, NM ; Kurucz, N ; Pettit, W ; Krause, VL ; Ehlers, G ; Muzari, MO ; Currie, BJ ; Hoffmann, AA (SPRINGER, 2023-11)
    Abstract Biosecurity strategies that aim to restrict the spread of invasive pests can benefit from knowing where incursions have come from and whether cryptic establishment has taken place. This knowledge can be acquired with genomic databanks, by comparing genetic variation in incursion samples against reference samples. Here we use genomic databanks to characterise incursions of two mosquito species within Australia, and to observe how genomic tracing methods perform when databank samples have limited genetic differentiation and were collected tens of generations ago. We used a deep learning method to trace a 2021 invasion ofAedes aegyptiin Tennant Creek, Northern Territory, to Townsville, Queensland, and to trace two years ofAe. albopictusincursions to two specific islands in the Torres Strait. Tracing had high precision despite 30–70 generations separating incursion and reference samples, and cross-validation of reference samples assigned them to the correct origin in 87% of cases. Similar precision was not achieved with PCAs, which performed particularly poorly for tracing when the invasion had been subject to strong drift effects. Targeted assays also provided additional information on the origin of the Tennant CreekAe. aegypti, in this case by comparingWolbachiainfection data and mitochondrial DNA variation. Patterns of relatedness and inbreeding indicated that Tennant Creek was likely invaded by one family ofAe. aegypti, while Torres Strait incursions were independent and indicated no cryptic establishment. Our results highlight the value of genomic databanks that remain informative over years and for a range of biological conditions.
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    Molecular identification of hymenopteran parasitoids and their endosymbionts from agromyzids
    Xu, X ; Hoffmann, AAA ; Umina, PAA ; Ward, SEE ; Coquilleau, MPP ; Malipatil, MBB ; Ridland, PMM (CAMBRIDGE UNIV PRESS, 2023-08)
    Three polyphagous pest Liriomyza spp. (Diptera: Agromyzidae) have recently invaded Australia and are damaging horticultural crops. Parasitic wasps are recognized as effective natural enemies of leafmining species globally and are expected to become important biocontrol agents in Australia. However, the hymenopteran parasitoid complex of agromyzids in Australia is poorly known and its use hindered due to taxonomic challenges when based on morphological characters. Here, we identified 14 parasitoid species of leafminers based on molecular and morphological data. We linked DNA barcodes (5' end cytochrome c oxidase subunit I (COI) sequences) to five adventive eulophid wasp species (Chrysocharis pubicornis (Zetterstedt), Diglyphus isaea (Walker), Hemiptarsenus varicornis (Girault), Neochrysocharis formosa (Westwood), and Neochrysocharis okazakii Kamijo) and two braconid species (Dacnusa areolaris (Nees) and Opius cinerariae Fischer). We also provide the first DNA barcodes (5' end COI sequences) with linked morphological characters for seven wasp species, with three identified to species level (Closterocerus mirabilis Edwards & La Salle, Trigonogastrella parasitica (Girault), and Zagrammosoma latilineatum Ubaidillah) and four identified to genus (Aprostocetus sp., Asecodes sp., Opius sp. 1, and Opius sp. 2). Phylogenetic analyses suggest C. pubicornis, D. isaea, H. varicornis, and O. cinerariae are likely cryptic species complexes. Neochrysocharis formosa and Aprostocetus sp. specimens were infected with Rickettsia. Five other species (Cl. mirabilis, D. isaea, H. varicornis, Opius sp. 1, and Opius sp. 2) were infected with Wolbachia, while two endosymbionts (Rickettsia and Wolbachia) co-infected N. okazakii. These findings provide background information about the parasitoid fauna expected to help control the leafminers.
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    The genome sequence of a spider mite, Tetranychus truncatus, provides insights into interspecific host range variation and the genetic basis of adaptation to a low-quality host plant
    Chen, L ; Yu, X-Y ; Xue, X-F ; Zhang, F ; Guo, L-X ; Zhang, H-M ; Hoffmann, AAA ; Hong, X-Y ; Sun, J-T (WILEY, 2023-10)
    The phytophagous mite Tetranychus truncatus is a serious pest in East Asia but has a relatively narrower host range than the pest mite Tetranychus urticae, which can feed on over 1200 plant species. Here, we generated a high-quality chromosomal level genome of T. truncatus and compared it with that of T. urticae, with an emphasis on the genes related to detoxification and chemoreception, to explore the genomic basis underlying the evolution of host range. We also conducted population genetics analyses (in 86 females from 10 populations) and host transfer experiments (in 4 populations) to investigate transcription changes following transfer to a low-quality host (Solanum melongena, eggplant), and we established possible connections between fitness on eggplant and genes related to detoxification and chemoreception. We found that T. truncatus has fewer genes related to detoxification, transport, and chemoreception than T. urticae, with a particularly strong reduction in gustatory receptor (GR) genes. We also found widespread transcriptional variation among T. truncatus populations, which varied in fitness on eggplant. We characterized selection on detoxification-related genes through ω values and found a negative correlation between expression levels and ω values. Based on the transcription results, as well as the fitness and genetic differences among populations, we identified genes potentially involved in adaptation to eggplant in T. truncatus. Our work provides a genomic resource for this pest mite and new insights into mechanisms underlying the adaptation of herbivorous mites to host plants.
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    Variation in the toxicity of a novel meta-diamide insecticide, broflanilide, among thrips pest species and developmental stages.
    Chen, J-C ; Cao, L-J ; Sun, L-N ; Gao, Y-F ; Cao, H-Q ; Ma, Z-Z ; Ma, L-J ; Shen, X-J ; Wang, J-X ; Gong, Y-J ; Hoffmann, AA ; Wei, S-J (Wiley, 2022-12)
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    A comprehensive assessment of insecticide resistance mutations in source and immigrant populations of the diamondback moth Plutella xylostella (L.)
    Shen, X-J ; Cao, L-J ; Chen, J-C ; Ma, L-J ; Wang, J-X ; Hoffmann, AA ; Wei, S-J (JOHN WILEY & SONS LTD, 2023-02-01)
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    Fungicides have transgenerational effects on Rhopalosiphum padi but not their endosymbionts
    Chirgwin, E ; Yang, Q ; Umina, PA ; Gill, A ; Soleimannejad, S ; Gu, X ; Ross, P ; Hoffmann, AA (JOHN WILEY & SONS LTD, 2022-11)
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    Unbiased population heterozygosity estimates from genome-wide sequence data
    Schmidt, TL ; Jasper, M-E ; Weeks, AR ; Hoffmann, AA (WILEY, 2021-10)
    Abstract Heterozygosity is a metric of genetic variability frequently used to inform the management of threatened taxa. Estimating observed and expected heterozygosities from genome‐wide sequence data has become increasingly common, and these estimates are often derived directly from genotypes at single nucleotide polymorphism (SNP) markers. While many SNP markers can provide precise estimates of genetic processes, the results of ‘downstream’ analysis with these markers may depend heavily on ‘upstream’ filtering decisions. Here we explore the downstream consequences of sample size, rare allele filtering, missing data thresholds and known population structure on estimates of observed and expected heterozygosity using two reduced‐representation sequencing datasets, one from the mosquito Aedes aegypti (ddRADseq) and the other from a threatened grasshopper, Keyacris scurra (DArTseq). We show that estimates based on polymorphic markers only (i.e. SNP heterozygosity) are always biased by global sample size (N), with smaller N producing larger estimates. By contrast, results are unbiased by sample size when calculations consider monomorphic as well as polymorphic sequence information (i.e. genome‐wide or autosomal heterozygosity). SNP heterozygosity is also biased when differentiated populations are analysed together while autosomal heterozygosity remains unbiased. We also show that when nucleotide sites with missing genotypes are included, observed and expected heterozygosity estimates diverge in proportion to the amount of missing data permitted at each site. We make three recommendations for estimating genome‐wide heterozygosity: (a) autosomal heterozygosity should be reported instead of (or in addition to) SNP heterozygosity; (b) sites with any missing data should be omitted and (c) populations should be analysed in independent runs. This should facilitate comparisons within and across studies and between observed and expected measures of heterozygosity.