The ecology of predatory hoverflies as ecosystem-service providers in agricultural systems

The main contemporary challenge for agriculture is to meet the food demands of the increasing world population while becoming more environmentally sustainable. One way to achieve this is through the promotion of functional biodiversity and the ecosystem (nature’s) services (ES) that it can provide. The Syrphinae subfamily is a widespread group of hoverflies with a high potential for that service. Hence, the present review aims to synthesize the existing literature on this group. This review is divided in three main sections. First, we focus on those aspects of the ecology of hoverflies that are relevant to their role in biological control. These are divided into nutrition, feeding preferences and prey detection of the different developmental stages, overwintering and the effect of landscape on their dispersal and efficacy. Second, we review the ES that predatory hoverflies can provide, particularly pollination and biological control. Finally, we discuss those farming practices that can affect the effectiveness of these Diptera as providers of ES. Overall, this review highlights the potential, as well as limitations and current gaps in knowledge, for enhancing the efficacy of hoverflies as ecosystem-service providers in agricultural systems.info:eu-repo/semantics/acceptedVersio

Ratios rather than concentrations of nutritionally important elements may shape honey bee preferences for ‘dirty water’

1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink ‘dirty water’ from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments. 2. Six minerals (NaCl, KCl, CaCl₂, MgCl₂, NH₄Cl, and KH₂PO₄) were used in mixtures to simulate different mineral stoichiometries, which may occur in ‘dirty water’, such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees (Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h. 3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral ‘dirty water’ should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets

The risk posed by the potato psyllid Bactericera cockerelli (Hemiptera: Triozidae) an important invasive pest of solanaceous crops

The potato psyllid Bactericera cockerelli is native to the Rocky Mountains in the United States and northern Mexico and is a had a major impact on solanaceous crops production. Severe outbreaks can reduce potato and tomato production by more than 85%. In addition to damaging plants by its feeding activity, the potato psyllid also transmits the important plant pathogen Candidatus Liberibacter solanaceaerum, which further increases the economic loss to growers. The potato psyllid has not yet been found in China but this international quarantine pest poses a major threat to China’s Solanaceous crop industry. To promote the prevention and control of this important pest, this article introduces the species’ biological characteristics, geographic distribution, host plant types, current distribution, crop damage symptoms, quarantine and current control strategies

Second asymptomatic carotid surgery trial (ACST-2) : a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86-1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91-1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable