As urbanisation increases globally and the natural environment becomes increasingly fragmented, the importance of urban green spaces for biodiversity conservation grows. In many countries, private gardens are a major component of urban green space and can provide considerable biodiversity benefits. Gardens and adjacent habitats form interconnected networks and a landscape ecology framework is necessary to understand the relationship between the spatial configuration of garden patches and their constituent biodiversity. A scale-dependent tension is apparent in garden management, whereby the individual garden is much smaller than the unit of management needed to retain viable populations. To overcome this, here we suggest mechanisms for encouraging 'wildlife-friendly' management of collections of gardens across scales from the neighbourhood to the city.

/pdf/scaling-up-from-gardens-biodiversity-conservation-in-urban-armsdwk79s.pdf

Scaling up from gardens: biodiversity conservation in urban environments

Declines in bumble bee species in the past 60 years are well documented in Europe, where they are driven primarily by habitat loss and declines in floral abundance and diversity resulting from agricultural intensification. Impacts of habitat degradation and fragmentation are likely to be compounded by the social nature of bumble bees and their largely monogamous breeding system, which renders their effective population size low. Hence, populations are susceptible to stochastic extinction events and inbreeding. In North America, catastrophic declines of some bumble bee species since the 1990s are probably attributable to the accidental introduction of a nonnative parasite from Europe, a result of global trade in domesticated bumble bee colonies used for pollination of greenhouse crops. Given the importance of bumble bees as pollinators of crops and wildflowers, steps must be taken to prevent further declines. Suggested measures include tight regulation of commercial bumble bee use and targeted use of environmentally comparable schemes to enhance floristic diversity in agricultural landscapes.

/pdf/decline-and-conservation-of-bumble-bees-1thgzzqlml.pdf

Decline and conservation of bumble bees

The idea of using species-specific behavior-modifying chemicals for the management of noxious insects in agriculture, horticulture, forestry, stored products, and for insect vectors of diseases has been a driving ambition through five decades of pheromone research. Hundreds of pheromones and other semiochemicals have been discovered that are used to monitor the presence and abundance of insects and to protect plants and animals against insects. The estimated annual production of lures for monitoring and mass trapping is on the order of tens of millions, covering at least 10 million hectares. Insect populations are controlled by air permeation and attract-and-kill techniques on at least 1 million hectares. Here, we review the most important and widespread practical applications. Pheromones are increasingly efficient at low population densities, they do not adversely affect natural enemies, and they can, therefore, bring about a long-term reduction in insect populations that cannot be accomplished with conventional insecticides. A changing climate with higher growing season temperatures and altered rainfall patterns makes control of native and invasive insects an increasingly urgent challenge. Intensified insecticide use will not provide a solution, but pheromones and other semiochemicals instead can be implemented for sustainable area-wide management and will thus improve food security for a growing population. Given the scale of the challenges we face to mitigate the impacts of climate change, the time is right to intensify goal-oriented interdisciplinary research on semiochemicals, involving chemists, entomologists, and plant protection experts, in order to provide the urgently needed, and cost-effective technical solutions for sustainable insect management worldwide.

Sex pheromones and their impact on pest management.

Parasitoids depend on a series of adaptations to the ecology and physiology of their hosts and host plants for survival and are thus likely highly susceptible to changes in environmental conditions. We analyze the effects of global warming and extreme temperatures on the life-history traits of parasitoids and interactions with their hosts. Adaptations of parasitoids to low temperatures are similar to those of most ectotherms, but these adaptations are constrained by the responses of their hosts. Life-history traits are affected by cold exposure, and extreme temperatures can reduce endosymbiont populations inside a parasitoid, eventually eliminating populations of endosymbionts that are susceptible to high temperatures. In several cases, divergences between the thermal preferences of the host and those of the parasitoid lead to a disruption of the temporal or geographical synchronization, increasing the risk of host outbreaks. A careful analysis on how host-parasitoid systems react to changes in temperature is needed so that researchers may predict and manage the consequences of global change at the ecosystem level.

Impact of extreme temperatures on parasitoids in a climate change perspective.

Recent declines of bee species have led to great interest in preserving and promoting bee populations for agricultural and wild plant pollination. Many correlational studies have examined the indirect effects of factors such as landscape context and land management practices and found great variation in bee response. We focus here on the evidence for effects of direct factors (i.e., food resources, nesting resources, and incidental risks) regulating bee populations and then interpret varied responses to indirect factors through their species-specific and habitatspecific effects on direct factors. We find strong evidence for food resource availability regulating bee populations, but little clear evidence that other direct factors are commonly limiting. We recommend manipulative experiments to illuminate the effects of these different factors. We contend that much of the variation in impact from indirect factors, such as grazing, can be explained by the relationships between indirect factors and floral resource availability based on environmental circumstances.

The Role of Resources and Risks in Regulating Wild Bee Populations

http://www.sussex.ac.uk/lifesci/goulsonlab/documents/goulson-et-al-animal-behaviour-2002.pdf

Can alloethism in workers of the bumblebee, Bombus terrestris, be explained in terms of foraging efficiency?

Many bumblebee species are declining at a rapid rate in the United Kingdom and elsewhere. This is commonly attributed to the decline in floral resources that has resulted from an intensification in farming practices. Here we assess growth of nests of the bumblebee, Bombus terrestris, in habitats providing different levels of floral resources. Experimental nests were placed out in conventional farmland, in farmland with flower-rich conservation measures and in suburban areas. Nests gained weight more quickly and attained a larger final size in suburban areas compared to elsewhere. The diversity of pollens gathered by bees was highest in suburban areas, and lowest in conventional farmland. Nests in suburban areas were also more prone to attack by the specialist bumblebee parasite Aphomia sociella, suggesting that this moth is more abundant in suburban areas than elsewhere. Overall, our results demonstrate that gardens provide a greater density and diversity of floral resources than farmland, and probably support larger populations of B. terrestris. Contrary to expectation, schemes deployed to enhance farmland biodiversity appear to have little measurable impact on nest growth of this bumblebee species. We argue that B. terrestris probably forage over a larger scale than that on which farms are managed, so that nest growth is determined by the management of a large number of neighbouring farms, not just that in which the nest is located.

/pdf/colony-growth-of-the-bumblebee-bombus-terrestris-in-improved-1hn0aai6nf.pdf

Colony growth of the bumblebee, Bombus terrestris, in improved and conventional agricultural and suburban habitats

http://www.trevorwilliams.info/cisneros_spinosad_2002.pdf

Toxic effects of spinosad on predatory insects

Summary 1. Calyptrate flies include numerous species that are disease vectors and have a high nuisance value, notably Musca domestica . Populations are often associated with livestock farms and domestic waste disposal facilities such as landfill, where the accumulating organic matter provides suitable breeding conditions for a range of species. 2. We examined the relationship between fly numbers and weather conditions using a 4-year data set of weekly fly catches from six sites in southern UK, together with meteorological data. The first 3 years were used to develop predictive models, and these were then used to forecast fly populations in the fourth year. The accuracy of these predictions was assessed by comparison with the actual fly catches for that year. Separate models were developed for M. domestica , Calliphora spp. and all calyptrate flies combined. 3. Predictions based only on humidity, temperature and rainfall were strongly correlated with observed data ( r 2 values ranged from 0·52 to 0·84), suggesting that fly population changes are largely driven by the weather rather than by biotic factors. We can forecast fly populations so that control measures need only be deployed when weather conditions are suitable for a fly outbreak, reducing the need for prophylactic insecticide use. 4. Climate change was simulated using the most recent predictions of future temperature increases. Our models predicted substantial increases in fly populations up to 244% by 2080 compared with current levels, with the greatest increases occurring in the summer months. 5. Synthesis and applications. Models developed use weather data to predict populations of pestiferous flies such as M. domestica , which may prove valuable in integrated control programmes. These models predict substantial increases in fly populations in the future under likely scenarios of climate change. If this occurs we may expect considerable increases in the incidence of fly-borne disease.

/pdf/predicting-calyptrate-fly-populations-from-the-weather-and-1yn0at66sc.pdf

Predicting calyptrate fly populations from the weather, and probable consequences of climate change

Lantana camara, a woody shrub originating in south and central America, is among the most widespread and troublesome exotic weeds of the old-world tropics. It invades pasture, crops and native ecosystems, causing substantial economic losses and environmental degradation. In Australia alone, L. camara is currently estimated to cover c. 40 000 km2. In glasshouse studies we demonstrate that L. camara requires cross-pollination to set fruit, and that honeybee visits result in effective pollination. Field studies carried out in Queensland, Australia, suggest that fruit set is limited by pollinator abundance, and that the main pollinator of L. camara throughout a substantial portion of its Australian range appears to be the honeybee, Apis mellifera. Seed set was strongly correlated with honeybee abundance, and at many sites, particularly in southern Queensland, honeybees were the only recorded flower visitors. Of 63 sites that were visited, seed set was highest at five sites where only honeybees were present. Hives are frequently stationed within and adjacent to areas such as National Parks that are threatened by this noxious weed. Management of honeybee populations may provide a powerful tool for cost-effective control of L. camara that has previously been overlooked. We suggest that there are probably many other weeds, both in Australia and elsewhere, that benefit from honeybee pollination.

/pdf/synergistic-interactions-between-an-exotic-honeybee-and-an-28omx2rp0o.pdf

Lara C. Derwent

Papers

Can alloethism in workers of the bumblebee, Bombus terrestris, be explained in terms of foraging efficiency?

Colony growth of the bumblebee, Bombus terrestris, in improved and conventional agricultural and suburban habitats

Toxic effects of spinosad on predatory insects

Predicting calyptrate fly populations from the weather, and probable consequences of climate change

Synergistic interactions between an exotic honeybee and an exotic weed: pollination of Lantana camara in Australia