School of BioSciences - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 18
-
ItemFungicides have transgenerational effects on Rhopalosiphum padi but not their endosymbionts(JOHN WILEY & SONS LTD, 2022-11)
-
Item
-
ItemGenome-wide SNPs of vegetable leafminer, Liriomyza sativae: Insights into the recent Australian invasion(WILEY, 2022-07)Liriomyza sativae, the vegetable leafminer, is an important agricultural pest originally from the Americas, which has now colonized all continents except Antarctica. In 2015, L. sativae arrived on the Australian mainland and established on the Cape York Peninsula in the northeast of the country near the Torres Strait, which provides a possible pathway for pests to enter Australia and evade biosecurity efforts. Here, we assessed genetic variation in L. sativae based on genome-wide single nucleotide polymorphisms (SNPs) generated by double digest restriction-site-associated DNA sequencing (ddRAD-seq), aiming to uncover the potential origin(s) of this pest in Australia and contribute to reconstructing its global invasion history. Our fineRADstructure results and principal component analysis suggest Australian mainland populations were genetically close to populations from the Torres Strait, whereas populations from Asia, Africa, and Papua New Guinea (PNG) were more distantly related. Hawaiian populations were genetically distinct from all other populations of L. sativae included in our study. Admixture analyses further revealed that L. sativae from the Torres Strait may have genetic variation originating from multiple sources including Indonesia and PNG, and which has now spread to the Australian mainland. The L. sativae lineages from Asia and Africa appear closely related. Isolation-by-distance (IBD) was found at a broad global scale, but not within small regions, suggesting that human-mediated factors likely contribute to the local spread of this pest. Overall, our findings suggest that an exotic Liriomyza pest invaded Australia through the Indo-Papuan conduit, highlighting the importance of biosecurity programs aimed at restricting the movement of pests and diseases through this corridor.
-
ItemWarmer temperatures reduce chemical tolerance in the redlegged earth mite (Halotydeus destructor), an invasive winter-active pest(JOHN WILEY & SONS LTD, 2022-07)
-
Item
-
ItemThe mitogenome of Halotydeus destructor (Tucker) and its relationships with other trombidiform mites as inferred from nucleotide sequences and gene arrangements(WILEY, 2021-10)The redlegged earth mite, Halotydeus destructor (Tucker, 1925: Trombidiformes, Eupodoidea, Penthaleidae), is an invasive mite species. In Australia, this mite has become a pest of winter pastures and grain crops. We report the complete mitogenome for H. destructor, the first to represent the family Penthaleidae, superfamily Eupodoidea. The mitogenome of H. destructor is 14,691 bp in size, and has a GC content of 27.87%, 13 protein-coding genes, two rRNA genes, and 22 tRNA genes. We explored evolutionary relationships of H. destructor with other members of the Trombidiformes using phylogenetic analyses of nucleotide sequences and the order of protein-coding and rRNA genes. We found strong, consistent support for the superfamily Tydeoidea being the sister taxon to the superfamily Eupodoidea based on nucleotide sequences and gene arrangements. Moreover, the gene arrangements of Eupodoidea and Tydeoidea are not only identical to each other but also identical to that of the hypothesized arthropod ancestor, showing a high level of conservatism in the mitogenomic structure of these mite superfamilies. Our study illustrates the utility of gene arrangements for providing complementary information to nucleotide sequences with respect to inferring the evolutionary relationships of species within the order Trombidiformes. The mitogenome of H. destructor provides a valuable resource for further population genetic studies of this important agricultural pest. Given the co-occurrence of closely related, morphologically similar Penthaleidae mites with H. destructor in the field, a complete mitogenome provides new opportunities to develop metabarcoding tools to study mite diversity in agro-ecosystems. Moreover, the H. destructor mitogenome fills an important taxonomic gap that will facilitate further study of trombidiform mite evolution.
-
ItemHigh Incidence of Related Wolbachia across Unrelated Leaf-Mining Diptera(MDPI, 2021-09)The maternally inherited endosymbiont, Wolbachia pipientis, plays an important role in the ecology and evolution of many of its hosts by affecting host reproduction and fitness. Here, we investigated 13 dipteran leaf-mining species to characterize Wolbachia infections and the potential for this endosymbiont in biocontrol. Wolbachia infections were present in 12 species, including 10 species where the Wolbachia infection was at or near fixation. A comparison of Wolbachia relatedness based on the wsp/MLST gene set showed that unrelated leaf-mining species often shared similar Wolbachia, suggesting common horizontal transfer. We established a colony of Liriomyza brassicae and found adult Wolbachia density was stable; although Wolbachia density differed between the sexes, with females having a 20-fold higher density than males. Wolbachia density increased during L. brassicae development, with higher densities in pupae than larvae. We removed Wolbachia using tetracycline and performed reciprocal crosses between Wolbachia-infected and uninfected individuals. Cured females crossed with infected males failed to produce offspring, indicating that Wolbachia induced complete cytoplasmic incompatibility in L. brassicae. The results highlight the potential of Wolbachia to suppress Liriomyza pests based on approaches such as the incompatible insect technique, where infected males are released into populations lacking Wolbachia or with a different incompatible infection.
-
Item
-
ItemEmpowering Australian insecticide resistance research with genetic information: the road ahead(WILEY, 2021-02)Abstract Insecticides are important for chemical control of arthropod pests in agricultural systems but select for resistance as an adaptive trait. Identifying the genetic mechanism(s) underpinning resistance can facilitate development of genetic markers, which can be used in monitoring programs. Moreover, understanding of genetic mechanisms in a broader population genetic context can be used to infer the origins of resistance, predict the dynamics of resistance evolution and evaluate the efficacy of different management strategies. Transitioning genetic information successfully into practical solutions requires overcoming two major hurdles. Firstly, genetic mechanisms must be identified to develop genetic markers. Secondly, routine use of genetic markers is required to build substantial spatio‐temporal data on the distribution and frequency of resistance alleles. In this study, we demonstrate large knowledge gaps on the genetic mechanisms of insecticide resistances in Australia using eight established arthropod pests important to the grains industry: Bemisia tabaci (silverleaf whitefly), Frankliniella occidentalis (western flower thrips), Halotydeus destructor (redlegged earth mite), Helicoverpa armigera (cotton bollworm), Myzus persicae (green peach aphid), Plutella xylostella (diamondback moth), Tetranychus urticae (two‐spotted spider mite) and Thrips tabaci (onion thrips). Many resistances have not been characterised at the genetic level in most pests, even for chemical MoA groups with a long history of use in Australia. Moreover, monitoring of resistance is spatio‐temporally patchy, which precludes examination of long‐term trends or predictive modelling. We suggest that leveraging cumulative global knowledge of resistances to develop a priori candidate genes, and incorporation of genomic approaches, can help overcome the hurdles of embracing genetic information in resistance management. We highlight the recently invasive Spodoptera frugiperda (fall armyworm) as a case study where genetic markers and genomic approaches should prove useful in rapidly assessing the risk of this species to the Australian grains industry and other agricultural commodities. The uptake of genetic information into management can only occur once its benefit to empower insecticide resistance research is fully realised. Ultimately, the road ahead requires amalgamation of multifaceted data (genes, environment and spatio‐temporal replication) to better understand and predict the dynamics of resistance evolution.
-
ItemPotential for biological control of the vegetable leafminer, Liriomyza sativae (Diptera: Agromyzidae), in Australia with parasitoid wasps(WILEY, 2020-02)Abstract The vegetable leafminer, Liriomyza sativae Blanchard, poses a risk to vegetable and nursery production in mainland Australia since established in Cape York in 2015. Effective control overseas depends on maximising the impact of natural enemies. Problems with polyphagous Liriomyza pest species typically result from the destruction of their parasitoids by excessive use of non‐selective insecticides. Field studies are reviewed to identify parasitoid species involved in the biological control of L. sativae in open‐air and glasshouse production internationally and to assess the current knowledge of parasitoids of agromyzids in Australia. Overseas, invading Liriomyza populations have frequently been exploited by endemic parasitoids (often found on non‐pest agromyzid species), and non‐crop hosts have played a role as reservoirs of these parasitoids. The few published Australian field studies on the occurrence of agromyzid flies and their parasitoids show a large community of wasps attacking agromyzids, with species mainly from the Eulophidae, Pteromalidae and Braconidae. The most abundant recorded species are two cosmopolitan eulophid species, Hemiptarsenus varicornis (Girault) and Diglyphus isaea (Walker), and four Australian species: two eulophid species, Zagrammosoma latilineatum Ubaidillah and Closterocerus mirabilis Edwards & La Salle, one pteromalid species, Trigonogastrella sp., and one braconid species, Opius cinerariae Fischer, for which there is little biological information. One deficiency in the known assemblage in Australia is the absence of parasitoids from the Eucoilinae (Hymenoptera: Figitidae), a subfamily with several abundant species attacking agromyzids overseas. The composition and impact of the endemic parasitoid assemblage in Australia on populations of L. sativae needs to be assessed adequately in the field before the importation of additional exotic parasitoid species is contemplated. Overseas, two species, D. isaea and Dacnusa sibirica Telenga, are reared commercially for augmentative biological control, although the relatively high cost of production has restricted their release to protected cropping situations. Knowledge gaps remain locally about the taxonomy, distribution, host range and life cycle of parasitoids, and their potential impact on L. sativae.