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Taxonomic and ecogeographic information are potentially useful to select plants with beneficial traits for crop breeding. We tested the predictability of taxonomic and geoclimatic information in identifying wild potatoes with resistance in tubers to the potato tuber moth, Phthorimaea operculella Zeller. We tested the tubers of 47 wild potato species and the native potato Solanum tuberosum andigena for resistance to tuber moth larvae. Materials included 6585 genotypes representing 558 accessions. During screening, 28% of accessions had ≥ 60% undamaged tubers (moderate resistance) and of these, 10% were highly resistant to moth damage (i.e., ≥ 80% of tubers undamaged). Tubers of six potato species (S. commersonii, S. chiquidenum, S. albicans, S. acaule, S. demissum and S. boliviense) were significantly more resistant than tubers of S. tuberosum andigena, but resistant accessions also occurred among 22 other Solanum species. The frequency of resistant accessions was similar across phylogenetic clades, but resistance was more frequent in accessions with an endosperm balance number (EBN) of 1 or 4 and a ploidy level of 4 × or 6 ×. There was no apparent relation between altitude of origin and tuber resistance. Ecogeographical information was weakly related to resistance in some potato species; minimum temperatures during the coldest months at collection sites were positively related to resistance in S. boliviense and S. medians. Mean high temperatures and summertime precipitation were positively related to resistance in S. microdontum and S. acaule, respectively; however, ecogeographic information was not generally useful in predicting tuber resistance for other species or across all species. We recommend improvements to the phenotyping of potato accessions for resistance to tuber moth, including the use of taxonomic predictors. [ABSTRACT FROM AUTHOR]

A small proportion of the thousands of pesticides on the market today are associated with a disproportionately high incidence of severe acute pesticide poisoning and suicide. Paraquat stands out as one of the most lethal pesticides in common use, frequently involved in fatal incidents due to suicides or accidental exposure. Even though paraquat has been banned in over 67 countries, it is still widely used in many others, particularly in Asia and Latin America. Based on a literature review and consultations, this paper identifies options for replacing paraquat and distils practical lessons from numerous successes around the world. Our aim is to support regulators, policymakers, agronomists and the supply chain sector with practical information related to phasing out paraquat. Production data consistently failed to show any negative effects of banning paraquat on agricultural productivity. A wide range of alternative approaches to weed management and crop defoliation are available, many of which do not rely on herbicides. Over 1.25 million farmers in low- and middle-income countries (LMICs) successfully produce a range of crops for private voluntary standards (PVS) in food and fiber supply chains which prohibit paraquat use. We conclude from the findings of this study that eliminating paraquat will save lives without reducing agricultural productivity. Less hazardous and more sustainable alternatives exist. To enhance successful adoption and uptake of these methods on a wide scale, farmers require training and support within an enabling policy environment. [ABSTRACT FROM AUTHOR]

This study compares the effects of temperature (constant at 15, 20, 25, 30 and 35 °C) on adult longevity, oviposition, and nymph development of the brown planthopper, Nilaparvata lugens, on susceptible and resistant rice varieties. The resistant variety contained the BPH32 gene. In our experiments, nymphs failed to develop to adults at 15, 20 and 35 °C on either variety. Host resistance had its greatest effect in reducing adult survival at 20–25 °C and its greatest effect in reducing nymph weight gain at 25 °C. This corresponded with optimal temperatures for adult survival (20–25 °C) and nymph development (25–30 °C). At 25 and 30 °C, adult females achieved up to three oviposition cycles on the susceptible variety, but only one cycle on the resistant variety. Maximum egg-laying occurred at 30 °C due to larger numbers of egg batches produced during the first oviposition cycle on both the susceptible and resistant varieties, and larger batches during the second and third oviposition cycles on the susceptible variety; however, resistance had its greatest effect in reducing fecundity at 25 °C. This revealed a mismatch between the optimal temperatures for resistance and for egg production in immigrating females. Increasing global temperatures could reduce the effectiveness of anti-herbivore resistance in rice and other crops where such mismatches occur. [ABSTRACT FROM AUTHOR]

Since the beginning of the millennium, pesticide use has increased dramatically across Asia. However, it is still unclear what drives pesticide use among low-income farmers. We surveyed 275 farmers to investigate their decisions to apply or avoid pesticides on rice farms in southern Sri Lanka. Based on the information from the survey, we applied the Drivers-Pressures-State-Impacts-Responses framework to assess farmers' decisions as 'Responses' to changes in the rice ecosystem. Organic farmers mainly planted traditional varieties (64–77%) that they perceived as resistant to environmental stresses, including insect herbivores. Pesticide users, including integrated pest management farmers, and insecticide-free farmers (without insecticide use for ≥5 years) mainly planted modern rice varieties. There were no significant differences in reported rice yields among farmers using different management practices. However, fewer organic and insecticide-free farmers reported insect pests, particularly planthoppers, as a production constraint. Insecticide use by farmers was mainly an adaptive response to perceived risks of pest damage to high-yielding varieties. But farmers' responses were largely unsupported by any previous experience, suggesting that an increased availability and marketing of agrochemicals, and pressures to modernize production have influenced their decisions to use insecticides. Organic and insecticide-free farming practices were mainly restorative responses to perceived health risks associated with agrochemicals. We suggest that attention could be placed on promoting 'pesticide-free' or 'insecticide-free' farming through certification schemes as a viable option to break the lock-in of pesticide use on rice farms in the region and to provide additional product choices for rice consumers. [ABSTRACT FROM AUTHOR]

The diversification of farming landscapes is proposed as a method to increase farm productivity while at the same time enhancing pest regulation services provided by the natural enemies of insect herbivores. In this study, areas of diversified and conventional rice fields (with 2-14 fields per area = 0.42-1.31 ha) were established at three sites in the Philippines. The diversified areas had a series (> 40 per hectare) of small (< 2 m2) vegetable patches interspersed along rice bunds (levees). The abundance of planthopper and lepidopteran pests in these areas was monitored during two consecutive cropping seasons using sweep nets with rice yield and damage recorded at the end of each season. Mortality of brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas) eggs was monitored through field exposures of infested rice plants. There were no differences in rice yields between the conventional and diversified areas; however, a range of vegetables were produced as a supplementary product from the diversified rice areas. Diversification had no effect on planthopper or leaffolder (Cnaphalocrocis medinalis) abundance at the sites. Adult stemborers (Scirpophaga incertulas) were more abundant in the diversified areas; however, stemborer damage was similar between area treatments in both years. Vegetable patches did not increase parasitism of planthopper eggs; however, egg parasitism was highest close to the vegetable patches, suggesting that egg parasitoids interacted with the patches. Mortality of stemborer eggs was higher in the diversified areas than in the conventional areas. Parasitism due to Trichogramma japonicum and other egg parasitoids was also higher in the diversified areas. These results indicate the potential for vegetable patches to enhance the biological control services provided by egg parasitoids in rice fields; however, the study also indicates a need to carefully select vegetable crops that avoid any potential benefits for rice pests. We discuss the need for further research into diversified farms as a means of achieving sustainable rice production in Asia. [ABSTRACT FROM AUTHOR]

Decomposition of crop residues is a key process in agricultural systems that influences nutrient cycling and productivity. To clarify the roles of different groups of invertebrates in decomposition in paddy fields, we conducted a microcosm experiment, testing the effects of soil eluate filtered through a 21 μm mesh (control treatment) against the effects of microfauna (< 0.1 mm) and small gastropods (juvenile golden apple snails (Pomacea canaliculata), ca. 2 mm shell diameter), both separately and in combination, on rice straw decomposition. Rice straw in litterbags was incubated at the soil surface and in the soil together with standardized amounts of the respective detritivores for 10 and 21 days. Compared to the control treatment, snails and microfauna enhanced the reduction in straw mass on the soil surface by 19 and 22%, respectively. Both groups combined increased the reduction in straw biomass by 30%. Below the soil surface, the contribution of detritivores to decomposition was smaller, reducing straw biomass by just 1% (snails), 11% (microfauna) and 14% (snails + microfauna) compared to the control. The effects of microfauna and snails on decomposition were not fully additive, a pattern that could be due to competition or trophic interactions. Model selection using Akaike’s information criterion on nested linear mixed effects models led to a model including the main effects (snails, microfauna, position and time), several two-way interactions and the three-way interaction snails * microfauna * litterbag_position as the most parsimonious description of the data. Keeping straw accessible to aquatic invertebrate detritivores should be a suitable management strategy to enhance decomposition in paddy fields, although trade-offs with other management issues such as pest control need to be considered. [ABSTRACT FROM AUTHOR]

In a cross-disciplinary project (LEGATO) combining inter- and transdisciplinary methods, we quantify the dependency of rice-dominated socio-ecological systems on ecosystem functions (ESF) and the ecosystem services (ESS) the integrated system provides. In the collaboration of a large team including geo- and bioscientists, economists, political and cultural scientists, the mutual influences of the biological, climate and soil conditions of the agricultural area and its surrounding natural landscape have been analysed. One focus was on sociocultural and economic backgrounds, another on local as well as regional land use intensity and biodiversity, and the potential impacts of future climate and land use change. LEGATO analysed characteristic elements of three service strands defined by the Millennium Ecosystem Assessment (MA): (a) provisioning services: nutrient cycling and crop production; (b) regulating services: biocontrol and pollination; and (c) cultural services: cultural identity and aesthetics. However, in line with much of the current ESS literature, what the MA called supporting services is treated as ESF within LEGATO. As a core output, LEGATO developed generally applicable principles of ecological engineering (EE), suitable for application in the context of future climate and land use change. EE is an emerging discipline, concerned with the design, monitoring and construction of ecosystems and aims at developing strategies to optimise ecosystem services through exploiting natural regulation mechanisms instead of suppressing them. Along these lines LEGATO also aims to create the knowledge base for decision-making for sustainable land management and livelihoods, including the provision of the corresponding governance and management strategies, technologies and system solutions. [ABSTRACT FROM AUTHOR]

The Nilwala Ganga Basin of Sri Lanka includes important natural wetlands that are habitat for vulnerable animal and plant species. Flood protection and intensive rice production in the Basin have resulted in degraded acid soils and declining rice yields. However, traditional ‘maavee’ rice production outside the flood protection scheme has continued to generate a high-value rice product. This study reports on interviews conducted with farmers and other stakeholders to document the production practices and the potential environmental and economic benefits associated with maavee rice paddies. The maavee production system has prevailed for at least several decades. Farmers apply no chemicals to their paddies, relying instead on alluvial deposits as a source of nutrients, and on the natural pest and disease resistance of their traditional varieties. The maavee rice product can attain three times the selling price of rice from conventional farms making it more economically viable than conventional rice production. However, much of maavee production is for home consumption and the system is threatened by increasing labour costs, an ageing farming population and pressures to increase rice yields. Non-invasive production practices and the proximity of maavee paddies to regenerating wetlands in the Kirala Kele Sanctuary suggest that traditional paddies may constitute an important habitat for vulnerable wildlife; however, maavee farmers also perceive wetland birds as potentially damaging to rice. Based on a SWOT (strengths, weaknesses, opportunities and threats) analysis, we make recommendations for future research needs and potential management actions to safeguard the environmental and economic sustainability of the maavee system. [ABSTRACT FROM AUTHOR]

For over 50 years, host plant resistance has been the principal focus of public research to reduce planthopper and leafhopper damage to rice in Asia. Several resistance genes have been identified from native varieties and wild rice species, and some of these have been incorporated into high-yielding rice varieties through conventional breeding. However, adaptation by hoppers to resistant rice has been phenomenally rapid, and hopper populations with virulence against several resistance genes are now widespread. Directional genetic selection for virulent hoppers seems unlikely given the rapid pace of adaptation reported from field and laboratory studies. Among the alternative explanations for rapid hopper adaptation are changes (genetic, epigenetic, or community structure) in endosymbiont communities that become advantageous for planthoppers and leafhoppers that feed on resistant rice varieties. This review examines the nature of these symbiont communities and their functions in planthoppers and leafhoppers—focusing on their likely roles in mediating adaptation to plant resistance. Evidence from a small number of experimental studies suggests that bacterial and eukaryotic (including yeast-like) symbionts can determine or mediate hopper virulence on rice plants and that symbiont functions could change over successive generations of selection on both resistant and susceptible plants. The review highlights the potential complexity of rice hopper–symbiont interactions and calls for a more careful choice of research materials and methods to help reduce this complexity. Finally, the consequences of symbiont-mediated virulence adaptation for future rice breeding programs are discussed. [ABSTRACT FROM AUTHOR]

This study examines the effects of deforestation, and the habitat value of coffee and regenerated forest for tropical dung beetles, a functionally significant insect group. Pitfall trapping was conducted at 22 sites in a montane region of central Peru during April and November/December of 2002. Sites included primary and secondary forest, shadecoffee, regenerated forest and open farms (mainly with banana, yuca, and corn). Ordination techniques indicated that beetle assemblages in forests, regenerated forest and coffee were relatively similar. However, assemblage compositions in forested areas differed even at similar altitudes under the influence of biogeographical factors, and the assemblages at disturbed sites (farms/coffee) were influenced by beetle dispersal from adjacent forests. During dry months, when beetle activity is low, communities at all habitat types tended to converge because fewer unique species were recorded in forests at that time and habitat/ season generalists were dominant. Preliminary results also indicate that beetles in shady crops such as bananas responded to plant growth: as the banana canopy closed-in, producing more shade, open-habitat specialists retreated and forest/shade specialists invaded the sites. Chronosequence data at two of the sites demonstrate the rapid and dramatic changes in species richness and assemblage composition caused by deforestation. As forests become increasingly fragmented, and open farms continue to expand, dung beetles will become more restricted to the remaining fragments and reserves. In the mosaic landscape studied here, shade crops, like coffee, act as habitat and corridors for many dung beetle species. Small farm size and the consequent magnitude of edge effects, likely contributed to beetle movement between habitat types and determined the apparent generalist nature of many of the dung beetle species in this study. [ABSTRACT FROM AUTHOR]

This study examines the functional attributes of Neotropical dung beetles, and, based on the analysis, evaluates the role of dung beetles in pastures and tropical dry forest in El Salvador. Dung beetle diversity was lower in pastures than in forests. However, the total biomass of beetles at similarly-sized dung baits was frequently higher in pastures. Diversity loss followed structured patterns: (1) carrion and fruit feeding beetles were well represented (species number) in the forests but were largely absent from pastures; (2) large ball rollers and small fast tunnellers were present in forests but were absent from pastures; (3) large fast tunnellers and small slow tunnellers were poorly represented in pastures compared to forests but the few species that survived in pastures attained extremely high populations; and (4) each functional group in the species-poor pasture assemblages was divided almost equally into day and night active species. Substrate and habitat generalists that were present in both the forests and pastures were attracted to fruit and carrion in forested habitat but not in open pastures. In open habitats, flies and other insects may be the principal decomposers of decaying fruit and carrion. [ABSTRACT FROM AUTHOR]