Complex Outcomes from Insect and Weed Control with Transgenic Plants: Ecological Surprises?

Agriculture is fundamental for human survival through food production and is performed in ecosystems that, while simplified, still operate along ecological principles and retain complexity. Agricultural plants are thus part of ecological systems, and interact in complex ways with the surrounding terrestrial, soil, and aquatic habitats. We discuss three case studies that demonstrate how agricultural solutions to pest and weed control, if they overlook important ecological and evolutionary factors, cause “surprises”: (i) the fast emergence of resistance against the crop-inserted Bt-toxin in South Africa, (ii) the ecological changes generated by Bt-cotton landscapes in China, and (iii) the decline of the monarch butterfly, Danaus plexippus, in North America. The recognition that we work with complex systems is in itself important, as it should limit the belief in reductionist solutions. Agricultural practices lacking eco-evolutionary understanding result in “surprises” like resistance evolution both in weeds and pest insects, risking the reappearance of the “pesticide treadmill”—with increased use of toxic pesticides as the follow-up. We recommend prioritization of research that counteracts the tendencies of reductionist approaches. These may be beneficial on a short term, but with trade-off costs on a medium- to long-term. Such costs include loss of biodiversity, ecosystem services, long-term soil productivity, pollution, and reduced food quality

Monitoring Arthropods in Azorean Agroecosystems : the project AGRO-ECOSERVICES

We provided an inventory of all arthropods recorded in four Azorean agroecosystems (citrus orchards, low and high elevation maize fields and vineyards) from Terceira Island. A total of 50412 specimens were collected, belonging to four classes, 20 orders, 81 families and 200 identified species of arthropods. A total of 127 species are considered introduced (n = 22646) and 69 native non-endemic (n = 24117). Four endemic species were recorded with very few specimens (n = 14) and 3635 specimens belong to unidentified taxa recorded only at genus or family level. Five species are new records for Terceira Island, with Lagria hirta (Linnaeus, 1758) (Coleoptera, Tenebrionidae) being also a new record for the Azores. This publication contributes to a better knowledge of the arthropods communities present in agro-ecosystems of Terceira Island and will serve as a baseline for future monitoring schemes targeting the long-term change in arthropod diversity and abundance.This work was financed by FEDER (European Regional Development Fund) in 85% and by Azorean Public funds by 15% through the Operational Program Azores 2020, under the project AGRO-ECOSERVICES (ACORES-01-0145-FEDER-000073). The Darwin-Core database was prepared within the scope of the project AZORESBIOPORTAL -PORBIOTA (ACORES-01-0145-FEDER-000072).info:eu-repo/semantics/publishedVersio

Integrating adverse effect analysis into environmental risk assessment for exotic generalist arthropod biological control agents: a three-tiered framework

Environmental risk assessments (ERAs) are required before utilizing exotic arthropods for biological control (BC). Present ERAs focus on exposure analysis (host/prey range) and have resulted in approval of many specialist exotic biological control agents (BCA). In comparison to specialists, generalist arthropod BCAs (GABCAs) have been considered inherently risky and less used in classical biological control. To safely consider exotic GABCAs, an ERA must include methods for the analysis of potential effects. A panel of 47 experts from 14 countries discussed, in six online forums over 12 months, scientific criteria for an ERA for exotic GABCAs. Using four case studies, a three-tiered ERA comprising Scoping, Screening and Definitive Assessments was developed. The ERA is primarily based on expert consultation, with decision processes in each tier that lead to the approval of the petition or the subsequent tier. In the Scoping Assessment, likelihood of establishment (for augmentative BC), and potential effect(s) are qualitatively assessed. If risks are identified, the Screening Assessment is conducted, in which 19 categories of effects (adverse and beneficial) are quantified. If a risk exceeds the proposed risk threshold in any of these categories, the analysis moves to the Definitive Assessment to identify potential non-target species in the respective category(ies). When at least one potential non-target species is at significant risk, long-term and indirect ecosystem risks must be quantified with actual data or the petition for release can be dismissed or withdrawn. The proposed ERA should contribute to the development of safe pathways for the use of low risk GABCAs

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015

Body size inequality in ground beetle (Coleoptera: Carabidae) assemblages as a potential method to monitor environmental impacts of transgenic crops

Background and Purpose: Despite the obligatory post-market environmental monitoring of genetically modified (GM) crops in Europe, there are no available methodological guidelines or standards. Our aim was to examine the suitability of carabid body size inequality as a possible method for environmental monitoring.Material and Methods: We used carabids collected by pitfall traps in both insect-resistant GM (producing a Bacillus thuringiensis toxin) and isogenic maize plots at Flakkebjerg (Denmark), within the framework of the AMIGA Project. The body size distribution was calculated using various measures of size inequality: the Lorenz curve, the Gini and the Lorenz asymmetry coefficients every month during the summer 2014.Results: A total of 6339 carabids belonging to 38 species were captured and identified. The analysis detected a significant shift in size inequality between months, indicating the larger number of individuals of smaller-sized species later in the season, but no significant difference in inequality or mean body size was found between the assemblages in GM vs. isogenic maize plots.Conclusions: We concluded that the evaluation of body size inequality was sensitive to subtle changes in the structure of the carabid assemblages, and this method had the potential to be used during monitoring of the unanticipated environmental effects of GM plants.</p

Shifting preference between oviposition vs. host-feeding under changing host densities in two aphelinid parasitoids.

Destructive host-feeding is common in hymenopteran parasitoids. Such feeding may be restricted to host stages not preferred for oviposition. However, whether this is a fixed strategy or can vary according to resource levels or parasitoid needs is less clear. We tested the trade-off between host feeding and oviposition on two whitefly parasitoids under varying host densities. Females of two aphelinid parasitoids, Eretmocerus hayati and Encarsia sophia were exposed to nine different densities of their whitefly host, Bemisia tabaci, in single-instar tests to identify their functional response. Mixed-instar host choice tests were also conducted by exposing whiteflies at four densities to the parasitoids. We hypothesized that the parasitoid females can detect different host densities, and decide on oviposition vs. host-feeding accordingly. The results showed that both Er. hayati and En. sophia females tended to increase both oviposition and host-feeding with increased host density within a certain range. Oviposition reached a plateau at lower host density than host-feeding in Er. hayati, while En. sophia reached its oviposition plateau at higher densities. At low densities, Er. hayati parasitized most on first and second (the optimal ones), and fed most on third nymphal instars (the suboptimal one) of the whitefly host as theory predicts, while at high densities, both parasitism and host-feeding occurred on first and second instars which are preferred for oviposition. En. sophia parasitized most on third and fourth (the optimal ones), while fed on first instars (the suboptimal one) at low densities, and utilized third and fourth instars for both at high densities. In conclusion, oviposition vs. host-feeding strategy of parasitoid females was found to vary at different host densities. The balance between reserving optimal hosts for oviposition or using them for host-feeding depended on parasitoid life history and the availability of host resources

A novel morphological phenotype does not ensure reduced biotic resistance on an oceanic island

Biotic resistance by the local community is a prominent theory seeking to explain invasion success or failure. Oceanic island communities might be prone to invasions because of their assumed low biotic resistance, due to low species richness and ecological naivety towards invaders. Biotic resistance, however, has rarely been quantified. We attempted such quantification on Terceira Island (Azores, Portugal) using the sentinel prey method. Vanessa virginiensis, a widely distributed Nearctic butterfly, has not been recorded on Terceira, and their caterpillars have characteristic green–black stripes that make it dissimilar to other Azorean caterpillars. We examined whether predation rate (PR) on plasticine caterpillars mimicking the unfamiliar V. virginiensis pattern were lower than on familiar green ones. We exposed a total of 4479 caterpillars in native forests and five non-native habitats, the agroecosystems orchards, vineyards, low and high elevation maize fields, and intensively managed pastures. Overall PR was higher on caterpillars with the unfamiliar than with the familiar pattern (6.4%d⁻¹ vs. 3.7%d⁻¹). Invertebrate PR was also significantly higher on the unfamiliar than on the familiar pattern in the native forest (5.9%d⁻¹ vs. 1.0%d⁻¹), as well as vertebrate PR in orchards (4.8%d⁻¹ vs. 2.3%d⁻¹) and low elevation maize fields (7.4%d⁻¹ vs. 2.2%d⁻¹). Our results suggest the existence of biotic resistance even on a species-poor, remote island, and that a novel morphological phenotype in itself does not guarantee reduced predation pressure.This work was financed by FEDER (85%) and by Azorean Public funds (15%) through the Operational Program Azores 2020, project AGRO-ECOSERVICES (ACORES-01–0145-FEDER-000073).info:eu-repo/semantics/publishedVersio

Mean proportion of accepted hosts fed upon by parasitoid in single-instar and mixed-instar host experiment.

<p>A, B: Proportion of hosts fed upon in 24h by 1 d-old females of <i>Eretmocerus hayati</i> or <i>Encarsia sophia</i>, respectively. An area of 3.5 cm² of a leaf on a potted tomato plant was covered by a clip cage. Host instars, N1, N2, N3 and N4 are first, second, third and early fourth instars, respectively. Single-instar tests were performed on N2 for <i>Er. hayati</i>, and N3 for <i>En. sophia.</i></p