Search

A greater taxonomic and functional diversity of natural enemies in agroecosystems is frequently positively associated with more effective pest control, due to the complementarity of species or traits. But this diversity has declined with landscape homogenisation and loss of natural covers, particularly losing native species, which play an important role in pest suppression within crops.We evaluated the effect of landscape on coccinellid communities and aphids, and the relative contribution of coccinellids and aphids in shaping taxonomic and functional diversity of coccinellid communities in alfalfa fields.We characterised the landscape at 1 km radius surrounding 17 alfalfa fields, and the taxonomic and functional diversity of coccinellid communities collected throughout the season in alfalfa. Functional diversity indices considered four traits: body size, habitat specialisation, ubiquity and temporal variability.We found a positive association among native coccinellids in alfalfa and the amount of natural cover in the landscape, while aphids positively associated with agricultural cover. Also, we found a positive association among functional and taxonomic diversity indices with native coccinellids, and a negative association with exotics, demonstrating the contribution of native coccinellids in adding taxonomic and functional diversity to the aphidophagous communities in alfalfa fields. Aphids also associated positively with some functional and taxonomic diversity indices.Our results highlight the need to promote appropriate management practices in agricultural landscapes in order to conserve native coccinellid species in alfalfa, maintain a diversified species pool and their potential for aphid pest suppression. [ABSTRACT FROM AUTHOR]

Harmonia axyridis has invaded many regions of the world, with negative effects on local biodiversity, and thus it is of global concern for biological conservation. Recently it has invaded central Chile, one of the world's biodiversity hotspots, where the abundance and richness of ladybird species, particularly native species in agroecosystems, have declined following its arrival., Harmonia axyridis is particularly abundant in spring in the valleys of central Chile, but there is a dramatic decline in its abundance during the hot summer months., This study reports the occurrence of this invasive alien species in the summer at high altitudes (3578 m a.s.l.) in the Andes, which is the highest record worldwide. Individuals were observed on native cushion plants, in a unique environment rich in endemic species. Harmonia axyridis were active, reproducing and co-occurring with three other species of coccinellids., The dispersal of H. axyridis and other coccinellids from the valleys to high altitudes could represent a mechanism to escape the adverse high temperatures during the summer, returning to the valleys in autumn. Our study highlights the need to study the impacts of invasive alien species across a range of habitats, including not only agricultural landscapes, but also extreme ecosystems. [ABSTRACT FROM AUTHOR]

Aim Biological invasions are one of the major threats to biodiversity. Usually highly disturbed anthropogenic habitats favour invasion by alien species such as the coccinellid Harmonia axyridis. The spread and impact of this species has been documented in Europe and North America, but no information exists for South America. The aims of this study were to: (1) document the process of invasion of H. axyridis in Chile, (2) compare the abundance of H. axyridis in different habitats with varying degrees of disturbance and (3) assess change in the coccinellid assemblages in alfalfa fields over the 6 years following invasion. Location Chile. Methods The spread of H. axyridis was estimated using information from citizen scientists alongside records from the National Pest Surveillance System. The abundance of H. axyridis in different habitat types and of all coccinellids in alfalfa fields was assessed using yellow sticky traps. In alfalfa, the variations in species richness, Shannon and Simpson diversity and equitability indices through time were compared. Results Harmonia axyridis has rapidly increased in distribution: there have been 1875 records along 2863 km up to 2015 following the first observation in 2008 from Central Chile. The records span from sea level to 3200 m a.s.l. in the Andes. It has spread at an average rate of 184.8 km per year, preferentially colonizing disturbed habitats, but also invading native habitats. In alfalfa, it is particularly abundant and has become the dominant species, with a concomitant decrease in species richness and diversity of co-occurring species. Main conclusion Citizen science, alongside professional surveillance, has provided an effective method for studying invasion by H. axyridis, which is now well established and distributed across Chile. The rate of spread has been dramatic and the associated changes to the coccinellid community could disrupt the functioning, and ultimately resilience, of invaded ecosystems. [ABSTRACT FROM AUTHOR]

Aim Both anthropogenic habitat disturbance and the breadth of habitat use by alien species have been found to facilitate invasion into novel environments, and these factors have been hypothesized to be important within coccinellid communities specifically. In this study, we address two questions: (1) Do alien species benefit more than native species from human-disturbed habitats? (2) Are alien species more generalized in their habitat use than natives within the invaded range or can their abundance patterns be explained by specialization on the most common habitats? Location Chile. Methods We quantified the use of different habitat types by native and alien coccinellid beetles by sampling individuals in nine habitat types that spanned a gradient in disturbance intensity, and represented the dominant natural, semi-natural and agricultural habitats in the landscape. Results Our results provide strong support for the hypotheses that more-disturbed habitats are differentially invaded. Both the proportion of alien individuals and the proportion of alien species increased significantly with increasing disturbance intensity. In contrast, we found no evidence that alien species were more generalized in their habitat use than native species; in fact, the trend was in the opposite direction. The abundance of specialized alien coccinellid species was not correlated with the area of the habitat types in the landscape. Main conclusion The results suggest that successfully established alien coccinellid species may be 'disturbance specialists' that thrive within human-modified habitats. Therefore, less-disturbed agroecosystems are desirable to promote the regional conservation of native species within increasingly human-dominated landscapes. [ABSTRACT FROM AUTHOR]

Global biodiversity monitoring is urgently needed across the world to assess the impacts of environmental change on biodiversity. One way to increase monitoring is through citizen science. 'Citizen science' is a term that we use in this chapter to describe the diverse approaches that involve people in monitoring in a voluntary capacity, thus including participatory monitoring in which people work collaboratively with scientists in developing monitoring. There is great unrealised potential for citizen science, especially in Asia and Africa. However, to fulfil this potential citizen science will need to meet local needs (for participants, communities and decision makers, including people's own use of the data and their motivations to participate) and support global needs for biodiversity monitoring (including the United Nations' Sustainable Development Goals and the Aichi Biodiversity Targets). Activities should be feasible (for participants to provide scientifically rigorous data) and useful (for data users, from local to global scales). We use examples from across the world to demonstrate how monitoring can engage different types of participants, through different technologies, to record different variables according to different sampling approaches. Overall, these examples show how citizen science has the potential to provide a step change in our ability to monitor biodiversity--and hence respond to threats at all scales from local to global. [ABSTRACT FROM AUTHOR]