Variation among 532 genomes unveils the origin and evolutionary history of a global insect herbivore

The diamondback moth, Plutella xylostella is a cosmopolitan pest that has evolved resistance to all classes of insecticide, and costs the world economy an estimated US $4-5 billion annually. We analyse patterns of variation among 532 P. xylostella genomes, representing a worldwide sample of 114 populations. We find evidence that suggests South America is the geographical area of origin of this species, challenging earlier hypotheses of an Old-World origin. Our analysis indicates that Plutella xylostella has experienced three major expansions across the world, mainly facilitated by European colonization and global trade. We identify genomic signatures of selection in genes related to metabolic and signaling pathways that could be evidence of environmental adaptation. This evolutionary history of P. xylostella provides insights into transoceanic movements that have enabled it to become a worldwide pest.Minsheng You … Simon W. Baxter … Christopher M. Ward … et al

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Foliar pubescence and resistance to potato moth, Phthorimaea operculella, in Lycopersicon hirsutum

Pubescence characteristics for six accessions of Lycopersicon hirsutum Dunal and five accessions of L. hirsutum f. glabratum CH Mull. were determined and compared with those of an accession of cultivated tomato (L. esculentum Mill.). Removal of trichome exudates from excised leaflets using ethanol solution resulted in a reduced mortality and increased survival of potato moth (Phthorimaea operculella (Zeller)) neonates for the accessions that were most lethal when not treated with ethanol solution. No such treatment effect was evident for L. esculentum or for the L. hirsutum accession with least effect on neonates when its trichomes were intact. In a glasshouse experiment with caged intact plants, mortality of neonate P. operculella placed on the abaxial surface was greater on seven accessions than for L. esculentum. Neonates were less severely affected on the adaxial surface. Eleven days after inoculation, no live larvae were found on LA 1927, PI 127827, PI 134418, and PI 134428, and numbers on other accessions were lower than for L. esculentum. Eventual emergence of adults followed a similar trend. Multiple regression of insect data against pubescence indicated a significant correlation between density of type IV and VI trichomes and neonate mortality, decreased larval development and decreased adult emergence. Non-glandular type V trichomes were positively correlated with high survival of insects to 11 days and to adult. Though factors other than glandular trichomes are likely to be important, increased density of type IV and VI, along with reduced type V, are shown to be important to select in breeding for P. operculella resistance

Review of Nezara viridula (L.) management strategies and potential for IPM in field crops with emphasis on Australia

Nezara viridula (L.) is a cosmopolitan, polyphagous heteropteran that causes economic damage to many crop species. At present, control of N. viridula in Australia and other countries relies heavily upon insecticides, most of which are disruptive to beneficial insects, constituting a constraint on integrated pest management (IPM). Much research has been conducted into non-chemical control methods for N. viridula. This paper reviews the potential for and limitations of sterile insect technique, classical, inundative and conservation biological control, and trap cropping. None of these techniques appear to be adequate for control of N. viridula when used alone but there is scope for these non-chemical approaches to be adopted for use in integrated management of this pest. A proposal is given for one such integrated approach for future development. It includes biopesticides, trap crops and carefully targeted habitat manipulation to enhance arthropod natural enemies as well as area-wide management and grower education

Effect of plant variety, plant age and photoperiod on glandular pubescence and host-plant resistance to potato moth (Phthorimaea operculella) in Lycopersicon spp.

The effect of plant age and daylength on glandular pubescence was determined for two lines of tomato derived from Lycopersicon hirsutum (BTN 979 and LA 1777A) and a variety of L. esculentum (N 91-1-1-1-1). Densities of type I, IV, VI and VII glandular trichomes were lowest in N 91-1-1-1-1 and, over all varieties, were more dense on plants aged greater than 6 wk. Daylength interacted with variety to significantly affect densities of type VII trichomes only. Host-plant resistance to Phthorimaea operculella was determined in preliminary tests using insects cultured from founders from a potato crop and in confirmatory tests using (less readily available) insects recovered from foliage of a tomato crop. Mortality of ex-potato neonates on LA 1777 A and BTN 979 foliage was higher 18 h after placement than for N 91-1-1-1-1, with no effect of day length or plant age. Mortality for ex-tomato neonates followed a similar trend. Ten days later, two-thirds of ex-tomato larvae had established mines on N 91-1-1-1-1 but fewer (16.7%) were live on other varieties. Stepwise multiple regression using variety as the sole factor was significant (P<0.001) in accounting for 61.4% of the variation in ex-tomato larval survival but addition of other factors to the regression model was not significant. BTN 979 supported fewer, smaller adults to develop than did N 91-1-1-1-1, whilst no adults developed on LA 1777 A. In a non-choice test using ex-potato adults, significantly more eggs were laid on N 91-1-1-1-1 than on L. hirsutum varieties and 9-wk-old plants were preferred over plants three weeks older or younger. The same variety and plant age trends were evident in a free-choice test using ex-tomato adults

Phytoplasmas and their insect vectors: implications for date palm.

Phytoplasmas are transmitted chie\ufb02 y by insects, most commonly planthoppers and leafhoppers. Molecular genetic analyses have improved the understanding of phytoplasma taxonomy, and also enhanced the ability to identify phytoplasmas detected in hosts and insect vectors. Date palm is affected by Al-Wijam disease in Saudi Arabia and molecularly indistinguishable phytoplasmas (16SrI group) were recovered from affected palms and from Cicadulina bipunctata , an insect commonly found on the palms. The phytoplasma that is associated with the lethal yellowing disease in coconut palm (16SrIV-A) can also infect date palm. In the Americas lethal yellowing is likely to be transmitted by Haplaxius crudus (formerly Myndus crudus ). Texas phoenix decline is reported from warm regions of South-East USA and may be transmitted by two species of Derbidae. Phytoplasmas belonging to the 16SrIV-F and 16SrXIV groups have also been identi\ufb01 ed from date palm growing in the USA and Africa respectively, though vectors have not been identi\ufb01 ed. Preventing spread in infected vegetative planting material and of vectors is key to limiting the impact of phytoplasma diseases. Management in affected areas can use antibiotics on high value trees, but this is not economical for extensive crops. In these situations, vector control by insecticide use or habitat management can be useful, but the long lifespan of individual palms means that even low vector pressure can lead to infection over successive years. The development of resistant varieties and replanting is the most effective long-term approach developed so far for phytoplasma disease management in this plant species

First record of Meloidogyne trifoliophila in Australia

Meloidogyne trifoliophila (Bernard and Eisenback) has been recorded for the first time in Australia on white clover (Trifolium repens L.) roots on the north coast of New South Wales and southern Queensland. Identification was based on morphological observations and a host differential test