Search

The western corn rootworm, Diabrotica virgifera virgifera, is an insect pest of corn and population suppression with chemical insecticides is an important management tool. Traits conferring organophosphate insecticide resistance have increased in frequency amongst D. v. virgifera populations, resulting in the reduced efficacy in many corn-growing regions of the USA. We used comparative functional genomic and quantitative trait locus (QTL) mapping approaches to investigate the genetic basis of D. v. virgifera resistance to the organophosphate methyl-parathion. RNA from adult methyl-parathion resistant and susceptible adults was hybridized to 8331 microarray probes. The results predicted that 11 transcripts were significantly up-regulated in resistant phenotypes, with the most significant (fold increases >/= 2.43) being an a-esterase-like transcript. Differential expression was validated only for the aesterase (ST020027A20C03), with 11- to 13-fold greater expression in methyl-parathion resistant adults (P

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of corn in the United States, and recent management of western corn rootworm has included planting of Bt corn. Beginning in 2009, western corn rootworm populations with resistance to Cry3Bb1 corn and mCry3A corn were found in Iowa and elsewhere. To date, western corn rootworm populations have remained susceptible to corn producing Bt toxin Cry34/35Ab1. In this study, we used single-plant bioassays to test field populations of western corn rootworm for resistance to Cry34/35Ab1 corn, Cry3Bb1 corn, and mCry3A corn. Bioassays included nine rootworm populations collected from fields where severe injury to Bt corn had been observed and six control populations that had never been exposed to Bt corn. We found incomplete resistance to Cry34/35Ab1 corn among field populations collected from fields where severe injury to corn producing Cry34/35Ab1, either singly or as a pyramid, had been observed. Additionally, resistance to Cry3Bb1 corn and mCry3A corn was found among the majority of populations tested. These first cases of resistance to Cry34/35Ab1 corn, and the presence of resistance to multiple Bt toxins by western corn rootworm, highlight the potential vulnerability of Bt corn to the evolution of resistance by western corn rootworm. The use of more diversified management practices, in addition to insect resistance management, likely will be essential to sustain the viability of Bt corn for management of western corn rootworm.

Crops producing toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage insect pests including western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), which is a significant pest of maize in the United States and Europe. However, the widespread use of Bt maize places intense selection pressure on pest populations to evolve resistance, and field-evolved resistance to Bt maize by western corn rootworm has been documented in the United States. In conjunction with non-Bt refuges, fitness costs of Bt resistance can delay resistance evolution. Fitness costs arise in the absence of Bt toxin when individuals with resistance alleles have lower fitness than Btsusceptible genotypes. We quantified the level of resistance and fitness costs of resistance for a strain of western corn rootworm with laboratoryselected resistance to transgenic maize (Zea mays L.) producing Bt toxin Cry3Bb1. Survival to adulthood on Cry3Bb1 maize was more than twofold higher for resistant insects vs. susceptible insects, which is similar to the magnitude of resistance first observed in the field. Fitness costs were measured in two experiments; the first used maize hybrids and the second used inbred lines. The experiment with maize hybrids compared resistant and susceptible strains while the experiment with maize inbreds compared resistant, susceptible and heterozygous genotypes. The only nonrecessive fitness cost detected (i.e. cost affecting heterozygotes) was for adult size. Recessive fitness costs (i.e. costs affecting the resistant strain) were observed for developmental rate, female survival and egg viability. However, when reared on non-Bt maize, the resistant strain also displayed higher fecundity, higher survival for males and greater adult longevity compared to the susceptible strain. These results suggest that resistance to Bt maize by western corn rootworm may not impose substantial fitness costs, and consequently, may ev

Key biological characteristics of the harlequin fish Othos dentex, a representative of a monospecific genus of the Anthiinae (Serranidae), were determined from samples collected around reefs on the south coast of Western Australia. The females of this relatively long-lived species (maximum recorded age in this study=37years) attained only a slightly greater maximum total length and age than males and neither the length nor the age-frequency distributions showed a conspicuous sex-based bimodality. Furthermore, gonads from a wide size and age range of O. dentex were shown by histology, at several locations along their length, to always comprise exclusively either ovarian or testicular tissues. Thus, O. dentex is a gonochorist, a sexual pattern only previously recorded definitively for one other anthiine serranid, i.e. Epinephelides armatus, which also occurs in south-western Australia. Similar to E. armatus, O. dentex possesses 'solid' testes with a central sperm duct, thereby differing in structure from those typically found in serranids, in which there is a central membrane-bound 'ovarian' lumen and peripherally located sperm sinuses. The gonadal characteristics and sexual pattern of these two gonochoristic anthiines are not consistent with a recent proposal for the trends exhibited by the evolution of gonochorism and protogyny within the Serranidae. Othos dentex has indeterminate fecundity and a protracted spawning period (7months) and, on the basis of underwater observations and a low gonado-somatic index (IG) for males, is a pair spawner, which is unusual for a gonochorist of a serranid or member of a related family. While the large spots on the lower half of the body of O. dentex are shown quantitatively to be similarly yellow in juveniles and adult females, they then become blue in males at maturity and this intensifies during the spawning period, when they presumably play an important role in agonistic interactions among males and courtship with females. The a

Background: Urinary incontinence (UI) affects half of patients hospitalised after stroke and is often poorly managed. Cochrane systematic reviews have shown some positive impact of conservative interventions (such as bladder training) in reducing UI, but their effectiveness has not been demonstrated with stroke patients. Methods: We conducted a cluster randomised controlled feasibility trial of a systematic voiding programme (SVP) for the management of UI after stroke. Stroke services were randomised to receive SVP (n = 4), SVP plus supported implementation (SVP+, n = 4), or usual care (UC, n = 4). Results: It was possible to recruit patients (413; 164 SVP, 125 SVP+, and 124 UC) and participant retention was acceptable (85% and 88% at six and 12 weeks, respectively). There was no suggestion of a beneficial effect on the main outcome at six (SVP versus UC: odds ratio (OR) 0.94, 95% CI: 0.46 to 1.94; SVP+ versus UC: OR: 0.62, 95% CI: 0.28 to 1.37) or 12 weeks (SVP versus UC: OR: 1.02, 95% CI: 0.54 to 1.93; SVP+ versus UC: OR: 1.06, 95% CI: 0.54 to 2.09). Conclusions: The trial has met feasibility outcomes of participant recruitment and retention. It was not powered to demonstrate effectiveness, but there is some evidence of a potential reduction in the odds of specific types of incontinence. A full trial should now be considered.