A haploid diamondback moth (Plutella xylostella L.) genome assembly resolves 31 chromosomes and identifies a diamide resistance mutation.

The diamondback moth, Plutella xylostella (L.), is a highly mobile brassica crop pest with worldwide distribution and can rapidly evolve resistance to insecticides, including group 28 diamides. Reference genomes assembled using Illumina sequencing technology have provided valuable resources to advance our knowledge regarding the biology, origin and movement of diamondback moth, and more recently with its sister species, Plutella australiana. Here we apply a trio binning approach to sequence and annotate a chromosome level reference genome of P. xylostella using PacBio Sequel and Dovetail Hi-C sequencing technology and identify a point mutation that causes resistance to commercial diamides. A P. xylostella population collected from brassica crops in the Lockyer Valley, Australia (LV-R), was reselected for chlorantraniliprole resistance then a single male was crossed to a P. australiana female and a hybrid pupa sequenced. A chromosome level 328 Mb P. xylostella genome was assembled with 98.1% assigned to 30 autosomes and the Z chromosome. The genome was highly complete with 98.4% of BUSCO Insecta genes identified and RNAseq informed protein prediction annotated 19,002 coding genes. The LV-R strain survived recommended field application doses of chlorantraniliprole, flubendiamide and cyclaniliprole. Some hybrids also survived these doses, indicating significant departure from recessivity, which has not been previously documented for diamides. Diamide chemicals modulate insect Ryanodine Receptors (RyR), disrupting calcium homeostasis, and we identified an amino acid substitution (I4790K) recently reported to cause diamide resistance in a strain from Japan. This chromosome level assembly provides a new resource for insect comparative genomics and highlights the emergence of diamide resistance in Australia. Resistance management plans need to account for the fact that resistance is not completely recessive.

Gestational diabetes in women living with HIV in Botswana: lower rates with dolutegravir- than with efavirenz-based antiretroviral therapy.

BACKGROUND: There are few data on the prevalence of gestational diabetes (GDM) in pregnant women living with HIV (WLHIV) in sub-Saharan Africa, particularly those using integrase strand transfer inhibitors such as dolutegravir (DTG). METHODS: We prospectively enrolled pregnant WLHIV and pregnant women without HIV ≥18 years old in Gaborone, Botswana, excluding those with pre-existing diabetes. We screened for GDM using a 75 g oral glucose tolerance test (OGTT) performed at 24-28 weeks' gestation or at the earliest prenatal visit for those presenting after 28 weeks. Logistic regression models were fitted to assess the association between maternal HIV infection and GDM. Subgroup analyses were performed among WLHIV to assess the association between maternal antiretroviral therapy (ART) in pregnancy [DTG vs. efavirenz (EFV) with tenofovir/emtricitabine] and GDM. RESULTS: Of 486 pregnant women, 66.5% were WLHIV, and they were older than women without HIV (median age 30 vs. 25 years, P < 0.01). Among WLHIV, 97.8% had an HIV-1 RNA level < 400 copies/mL at enrolment. Overall, 8.4% had GDM with similar rates between WLHIV and those without HIV (9.0% vs. 7.4%). The WLHIV receiving DTG-based ART had a 60% lower risk for GDM compared with those on EFV-based ART (adjusted odds ratio = 0.40, 95% CI: 0.18-0.92) after adjusting for confounders. CONCLUSIONS: Pregnant WLHIV on ART in Botswana were not at increased risk of GDM compared with women without HIV. Among WLHIV, the risk of GDM was lower with DTG- than with EFV-based ART. Further studies with larger cohorts are warranted to confirm these findings.

Formulation and application of the entomopathogenic fungus: Zoophthora radicans (Brefeld) Batko (Zygomycetes: Entomophthorales).

AIMS: To isolate and formulate a native strain of Zoophthora radicans naturally infecting larvae of diamondback moth, Plutella xylostella, existing in South Australia and to provide evidence that formulation of the fungus is effective against P. xylostella larvae, and therefore, it could be used as a tool in pest management of this insect. METHODS AND RESULTS: Dose-response bioassays using formulated and unformulated forms of the fungus strain were carried out against third instar larvae of P. xylostella. Results obtained have indicated a significant increase in the larval mortality when higher concentrations of a formulated form of the fungus strain were applied compared to the treatments with the unformulated form (85·0 vs 57·5% of larval mortality, respectively, at the top concentration of 10(7) conidia/ml). The median lethal concentration (LC50) for a formulated form was 100 times less than that of the unformulated form when they were applied against the third instar larvae of P. xylostella. In addition, the formulation used in the present bioassays has preserved the viability of introduced fungus conidia for longer time in comparison with the unformulated conidia. CONCLUSIONS: The effective application of a formulated fungus strain against P. xylostella larvae constitutes the first step towards its use in pest management of this insect. SIGNIFICANCE AND IMPACT OF THE STUDY: The formulated fungus in inverted emulsion could be used as an alternative tool to insecticides in pest management of P. xylostella larvae because of the development of resistance to insecticides in the treated larvae.

Induction and transmission of tolerance to the synthetic pesticide emamectin benzoate in field and laboratory populations of diamondback moth.

Field surveys of pest insect pest populations in agroecosystems reveal low but significant levels of tolerance to synthetic and biological pesticides but fail to uncover resistance alleles in test crosses. To study the potential of inducible mechanisms to generate tolerance to synthetic pesticides, we performed baseline susceptibility studies in field and laboratory populations of diamondback moth, Plutella xylostella (L.), to commercial formulations of emamectin benzoate. Pesticide exposure in the field caused elevated levels of tolerance, which decreased in field-collected populations after maintaining insects with pesticide-free diet in the laboratory. Because no significant resistance alleles were identified in back-crossed individuals, the observed increase in tolerance was probably not based on preexisting recessive resistance mechanisms in the population. Instead, the genetic analysis after five and 12 generations is compatible with a transient up-regulation of an immune and metabolic status in tolerant insects that can be transmitted to offspring by a maternal effect. Although the epigenetic effects contributed to incremental increases in tolerance in the first five generations, other resistance mechanisms that are transmitted genetically predominate after 12 generations of increased exposure to the pesticide.

Antiretroviral regimens in pregnancy and breast-feeding in Botswana.

BACKGROUND: The most effective highly active antiretroviral therapy (HAART) to prevent mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) in pregnancy and its efficacy during breast-feeding are unknown. METHODS: We randomly assigned 560 HIV-1-infected pregnant women (CD4+ count, > or = 200 cells per cubic millimeter) to receive coformulated abacavir, zidovudine, and lamivudine (the nucleoside reverse-transcriptase inhibitor [NRTI] group) or lopinavir-ritonavir plus zidovudine-lamivudine (the protease-inhibitor group) from 26 to 34 weeks' gestation through planned weaning by 6 months post partum. A total of 170 women with CD4+ counts of less than 200 cells per cubic millimeter received nevirapine plus zidovudine-lamivudine (the observational group). Infants received single-dose nevirapine and 4 weeks of zidovudine. RESULTS: The rate of virologic suppression to less than 400 copies per milliliter was high and did not differ significantly among the three groups at delivery (96% in the NRTI group, 93% in the protease-inhibitor group, and 94% in the observational group) or throughout the breast-feeding period (92% in the NRTI group, 93% in the protease-inhibitor group, and 95% in the observational group). By 6 months of age, 8 of 709 live-born infants (1.1%) were infected (95% confidence interval [CI], 0.5 to 2.2): 6 were infected in utero (4 in the NRTI group, 1 in the protease-inhibitor group, and 1 in the observational group), and 2 were infected during the breast-feeding period (in the NRTI group). Treatment-limiting adverse events occurred in 2% of women in the NRTI group, 2% of women in the protease-inhibitor group, and 11% of women in the observational group. CONCLUSIONS: All regimens of HAART from pregnancy through 6 months post partum resulted in high rates of virologic suppression, with an overall rate of mother-to-child transmission of 1.1%. (ClinicalTrials.gov number, NCT00270296.)

Pyrethroid resistance in Australian field populations of the sheep body louse, Bovicola (Damalinia) ovis.

Synthetic pyrethroid (SP) resistance has developed in Australian field populations of the sheep body louse, Bovicola (Damalinia) ovis. Laboratory bioassays were used to measure the susceptibility of lice to cypermethrin and the other registered SPs. Results of these bioassays indicated resistance to cypermethrin, deltamethrin, cyhalothrin and alphacypermethrin. So far, high-level resistance has been diagnosed in only a few strains. The toxicological responses of these strains were clearly separated from those of the majority of louse strains tested. Furthermore, these strains had survived immersion in commercial SP dips. The level of resistance described in some strains was sufficient to cause pour-on products to fail despite the fact that the LC50s of these strains fell within the normal range of field responses.