ORCID Profile
0000-0001-5107-7452
Current Organisations
University of Exeter, Penryn Campus
,
Ryerson University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.CUB.2019.05.036
Abstract: Despite the fact that migratory insects dominate aerial bioflows in terms of ersity, abundance, and biomass [1-6], the migration patterns of most species, and the effects of their annual fluxes between high- and low-latitude regions, are poorly known. One important group of long-range migrants that remain understudied is a suite of highly beneficial species of hoverfly in the tribe Syrphini, which we collectively term "migrant hoverflies." Adults are key pollinators [7-10] and larvae are significant biocontrol agents of aphid crop pests [11], and thus, it is important to quantify the scale of their migrations and the crucial ecosystem services they provide with respect to energy, nutrient, and biomass transport regulation of crop pests and pollen transfer. Such assessments cannot be made by sporadic observations of mass arrivals at ground level, because hoverflies largely migrate unnoticed high above ground. We used insect-monitoring radars [12] to show that up to 4 billion hoverflies (80 tons of biomass) travel high above southern Britain each year in seasonally adaptive directions. The long-range migrations redistribute tons of essential nutrients (nitrogen [N] and phosphorus [P]) and transport billions of pollen grains between Britain and Europe, and locally produced populations consume 6 trillion aphids and make billions of flower visits. Migrant hoverfly abundance fluctuated greatly between years, but there was no evidence of a population trend during the 10-year study period. Considering that many beneficial insects are seriously declining [7, 10, 13-19], our results demonstrate that migrant hoverflies are key to maintaining essential ecosystem services.
Publisher: SAGE Publications
Date: 04-06-2014
Abstract: This study investigates the differences in severity and correlates of depression symptoms among 1069 men and 267 women living with HIV in Ontario, Canada, who completed the 20-item Center for Epidemiologic Studies Depression Scale (CES-D). Women had higher CES-D scores than that of men (median [interquartile range]: 13 [5-26] versus 9 [3-20], P = .0004). More women had total CES-D scores (mild-moderate depression 44% versus 33%, P = .002) and (severe depression 31% versus 23%, P = .003). Unlike men, at age 40, women’s scores increased yearly (0.4 per increased year, P = .005). The distribution of scores differed by gender: There was no difference in the 10th percentile of depression scores, 0 (95% confidence interval [CI]: 1.0-1.0) but the 75th percentile of depression scores for women was 6 (95% CI: 2.0-10.0) points higher than that of men. Important gender differences exist in depression symptoms and in correlates of symptoms in people living with HIV.
Publisher: The Royal Society
Date: 04-2019
DOI: 10.1098/RSOS.190153
Abstract: The seasonal migration of huge numbers of hoverflies is frequently reported in Europe from mountain passes or spurs of land. The movement of such large numbers of beneficial insects is thought to provide significant ecosystem services in terms of pollination and pest control. Observations from the East Coast of the USA during the 1920s indicate the presence of migratory life histories among some hoverfly species there, but 90 years have now passed since the last reported observation of hoverfly migration in the USA. Here, we analyse video footage taken during a huge northward migration of hoverflies on 20 April 2017 on the West Coast of California. The quantification of migrant numbers from this footage allows us to estimate the passage of over 100 000 hoverflies in half an hour over a 200 m section of headland in Montaña de Oro State Park (San Luis Obispo County). Field collections and analysis of citizen science data indicate different species from the previously reported Eristalis tenax migrations on the East Coast of the USA and provide evidence for migration among North American hoverflies. We wish to raise awareness of this phenomenon and suggest approaches to advance the study of hoverfly migration in North America and elsewhere.
Publisher: Informa UK Limited
Date: 28-09-2022
DOI: 10.1080/09540121.2022.2126959
Abstract: Little is known about how the co-occurrence of psychosocial factors affect sub-populations of people living with HIV (PLWH). We used cross-sectional data from 999 PLWH, aged ≥19, accessing antiretroviral therapy (ART) in British Columbia, Canada (2007-2010) to examine associations between psychosocial factors and ART-related outcomes separately for trans/cis inclusive women heterosexual men and gay, bisexual, and other men who have sex with men (gbMSM). Multivariable logistic regression examined associations between psychosocial factors (0-3): any violence in the past 6 months, depressive symptoms in the past week, and current street drug use (heroin, crack, meth or speedball) with sub-optimal adherence (outcome 1: average annual ART adherence <95% from interview until end of follow-up, death, or December 31st, 2018) and ever viral rebound (outcome 2) adjusting for potential confounders. Of 999 PLWH (264 women, 382 heterosexual men, and 353 gbMSM), women and heterosexual men had significantly higher median counts than gbMSM. Overall, higher counts were associated with sub-optimal adherence (adjusted odds ratio [aOR] = 1.26/1-unit increase, 95%CI = 1.07-1.49). All effect estimates were of a greater magnitude among gbMSM, but not significant for women or heterosexual men, highlighting the need for population (e.g., gender and sexual orientation)-centered care and research.
Publisher: The Royal Society
Date: 22-09-2021
Abstract: The sun is the most reliable celestial cue for orientation available to daytime migrants. It is widely assumed that diurnal migratory insects use a ‘time-compensated sun compass’ to adjust for the changing position of the sun throughout the day, as demonstrated in some butterfly species. The mechanisms used by other groups of diurnal insect migrants remain to be elucidated. Migratory species of hoverflies (Diptera: Syrphidae) are one of the most abundant and beneficial groups of diurnal migrants, providing multiple ecosystem services and undergoing directed seasonal movements throughout much of the temperate zone. To identify the hoverfly navigational strategy, a flight simulator was used to measure orientation responses of the hoverflies Scaeva pyrastri and Scaeva selenitica to celestial cues during their autumn migration. Hoverflies oriented southwards when they could see the sun and shifted this orientation westward following a 6 h advance of their circadian clocks. Our results demonstrate the use of a time-compensated sun compass as the primary navigational mechanism, consistent with field observations that hoverfly migration occurs predominately under clear and sunny conditions.
Publisher: Informa UK Limited
Date: 02-12-2021
Publisher: The Royal Society
Date: 20-05-2020
Abstract: Pollinator declines, changes in land use and climate-induced shifts in phenology have the potential to seriously affect ecosystem function and food security by disrupting pollination services provided by insects. Much of the current research focuses on bees, or groups other insects together as ‘non-bee pollinators’, obscuring the relative contribution of this erse group of organisms. Prominent among the ‘non-bee pollinators’ are the hoverflies, known to visit at least 72% of global food crops, which we estimate to be worth around US$300 billion per year, together with over 70% of animal pollinated wildflowers. In addition, hoverflies provide ecosystem functions not seen in bees, such as crop protection from pests, recycling of organic matter and long-distance pollen transfer. Migratory species, in particular, can be hugely abundant and unlike many insect pollinators, do not yet appear to be in serious decline. In this review, we contrast the roles of hoverflies and bees as pollinators, discuss the need for research and monitoring of different pollinator responses to anthropogenic change and examine emerging research into large populations of migratory hoverflies, the threats they face and how they might be used to improve sustainable agriculture.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1FO04078B
Abstract: There is an increasing awareness of the link between food breakdown during chewing and its nutrient release and absorption in the gastrointestinal tract. However, how oral processing behaviour varies among different ethnic groups, and how such difference further impacts on bolus characteristics and consequently glycemic response (GR) are not well understood. In this study, we recruited a group of Asian (Chinese) subjects in China (
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1FO02057A
Abstract: The aim of this study was to investigate the impact of wheat bran fortification on the mastication process of bread. White wheat bread (WB) and bran-fortified wheat bread (BB) were consumed by eighteen panellists. The bolus was collected at four different mastication stages and characterized by properties of hydration, particle size, and texture. The results showed that there was no difference between the two bread s les in terms of swallowable bolus moisture. BB with a harder and denser texture produced more small particles and had a slightly shorter chewing time than WB during mastication. Moreover, bolus heterogeneity (
Publisher: The Royal Society
Date: 03-06-2020
Abstract: Large migrating insects, flying at high altitude, often exhibit complex behaviour. They frequently elect to fly on winds with directions quite different from the prevailing direction, and they show a degree of common orientation, both of which facilitate transport in seasonally beneficial directions. Much less is known about the migration behaviour of smaller (10–70 mg) insects. To address this issue, we used radar to examine the high-altitude flight of hoverflies (Diptera: Syrphidae), a group of day-active, medium-sized insects commonly migrating over the UK. We found that autumn migrants, which must move south, did indeed show migration timings and orientation responses that would take them in this direction, despite the unfavourability of the prevailing winds. Evidently, these hoverfly migrants must have a compass (probably a time-compensated solar mechanism), and a means of sensing the wind direction (which may be determined with sufficient accuracy at ground level, before take-off). By contrast, hoverflies arriving in the UK in spring showed weaker orientation tendencies, and did not correct for wind drift away from their seasonally adaptive direction (northwards). However, the spring migrants necessarily come from the south (on warm southerly winds), so we surmise that complex orientation behaviour may not be so crucial for the spring movements.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Trevor Hart.