Maurizio Sattin

Eight principles of integrated pest management

The use of pesticides made it possible to increase yields, simplify cropping systems, and forego more complicated crop protection strategies. Over-reliance on chemical control, however, is associated with contamination of ecosystems and undesirable health effects. The future of crop production is now also threatened by emergence of pest resistance and declining availability of active substances. There is therefore a need to design cropping systems less dependent on synthetic pesticides. Consequently, the European Union requires the application of eight principles (P) of Integrated Pest Management that fit within sustainable farm management. Here, we propose to farmers, advisors, and researchers a dynamic and flexible approach that accounts for the diversity of farming situations and the complexities of agroecosystems and that can improve the resilience of cropping systems and our capacity to adapt crop protection to local realities. For each principle (P), we suggest that (P1) the design of inherently robust cropping systems using a combination of agronomic levers is key to prevention. (P2) Local availability of monitoring, warning, and forecasting systems is a reality to contend with. (P3) The decision-making process can integrate cropping system factors to develop longer-term strategies. (P4) The combination of non-chemical methods that may be individually less efficient than pesticides can generate valuable synergies. (P5) Development of new biological agents and products and the use of existing databases offer options for the selection of products minimizing impact on health, the environment, and biological regulation of pests. (P6) Reduced pesticide use can be effectively combined with other tactics. (P7) Addressing the root causes of pesticide resistance is the best way to find sustainable crop protection solutions. And (P8) integration of multi-season effects and trade-offs in evaluation criteria will help develop sustainable solutions.

Allelic variation of the ACCase gene and response to ACCase-inhibiting herbicides in pinoxaden-resistant Lolium spp.

BACKGROUND The repeated use of acetyl-coenzyme A carboxylase (ACCase) inhibiting herbicides to control grass weeds has selected for resistance in Lolium spp. populations in Italy. The efficacy of pinoxaden, a recently marketed phenylpyrazoline herbicide, is of concern where resistance to ACCase inhibitors has already been ascertained. ACCase mutations associated with pinoxaden resistance were investigated, and the cross-resistance pattern to clodinafop, haloxyfop, sethoxydim, clethodim and pinoxaden was established on homo/heterozygous plants for four mutant ACCase alleles. RESULTS Seven different mutant ACCase alleles (1781-Leu, 1999-Leu, 2041-Asn, 2041-Val, 2078-Gly, 2088-Arg and 2096-Ala) and 13 combinations with two types of mutation were detected in the pinoxaden-resistant plants. The 1781-Leu allele appears to confer a dominant resistance to pinoxaden, clodinafop, haloxyfop, sethoxydim and clethodim at 60 g AI ha(-1) . The 2041-Asn and 2041-Val alleles are associated with dominant or partially dominant resistance to FOPs, no substantial resistance to DIMs and a moderate resistance to pinoxaden. The 2088-Arg allele endows a partially dominant resistance to clodinafop, sethoxydim and most likely to pinoxaden. In addition, non-target-site resistance mechanisms seem to be involved in pinoxaden resistance. CONCLUSION Almost all the ACCase mutations selected in the field by other ACCase inhibitors are likely to confer resistance to pinoxaden. Although pinoxaden is sometimes able to control FOP-resistant populations, it should not be considered as a sustainable ACCase resistance management tool. The presence of non-ACCase-based resistance mechanisms that could confer resistance to herbicides with different modes of action further complicates the resistance management strategies.

Characterisation of ALS genes in the polyploid species Schoenoplectus mucronatus and implications for resistance management.

BACKGROUND The polyploid weed Schoenoplectus mucronatus (L.) Palla has evolved target-site resistance to ALS-inhibiting herbicides in Italian rice crops. Molecular and genetic characterisation of the resistance mechanism is relevant to the evolution and management of herbicide resistance. The authors aimed (a) to study the organisation of the target-site loci in two field-selected S. mucronatus populations with different cross-resistance patterns, (b) to identify the mutations endowing resistance to ALS inhibitors and determine the role of these mutations by using transgenesis and (c) to analyse the implications for the management of the S. mucronatus populations. RESULTS Two complete ALS genes (ALS1 and ALS2) having an intron and a third partial intronless ALS gene (ALS3) were identified. The presence of multiple ALS genes was confirmed by Southern blot analyses, and ALS loci were characterised by examining cytosine methylation. In S. mucronatus leaves, the transcripts of ALS1, ALS2 and ALS3 were detected. Two mutations endowing resistance (Pro(197) to His and Trp(574) to Leu) were found in both resistant populations, but at different frequencies. Tobacco plants transformed with the two resistant alleles indicated that the Pro(197)-to-His substitution conferred resistance to SU and TP herbicides, while the allele with the Trp(574)-to-Leu substitution conferred cross-resistance to SU, TP, IMI and PTB herbicides. CONCLUSION Schoenoplectus mucronatus has multiple ALS genes characterised by methylated sites that can influence the expression profile. The two mutated alleles proved to be responsible for ALS resistance. At population level, the resistance pattern depends on the frequency of various resistant genotypes, and this influences the efficacy of various ALS-inhibiting herbicides.

Management of an ACCase-inhibitor-resistant Lolium rigidum population based on the use of ALS inhibitors: weed population evolution observed over a 7 year field-scale investigation

BACKGROUND A 7 year experiment was set up in 2002 to evaluate the long-term effects of weed management strategies based on graminicidal sulfonylureas (SUs) on the evolution of a Lolium rigidum population resistant to ACCase inhibitors in a continuous wheat cropping system. The strategies included the continued use of ALS inhibitors, the continued application of ACCase inhibitors and a simple resistance management strategy based on a biennial rotation of herbicide mode of action (MoA). RESULTS The efficacy of the tested SUs in the field decreased significantly, starting from the fourth treatment in all control strategies. Regardless of control strategy, the few survivors of the ALS treatment in the third season produced a significant number of ACCase- and ALS-resistant (multiple-resistant) progeny. Continuous ALS and biennial rotation of herbicides reduced weed densities, but L. rigidum conserved its ACCase resistance trait. Enhanced metabolism was detected in ALS-resistant plants, whereas target site was primarily involved in the ACCase-resistant individuals. CONCLUSION At the end of the experiment, multiple-resistant individuals were found in all samples coming from the control strategies investigated. The biennial rotation between ALS and other MoA appeared to delay the development of resistance to SUs over continuous treatments, but additional measures will likely need to be taken in order to make this sustainable in the long term, whereas the field efficacy of SUs remained relatively high until the end of the experiment. Integrated weed management with more diversity should be introduced in oversimplified cropping systems in order to sustainably manage resistant L. rigidum populations.

On-farm evaluation of inundative biological control of Ostrinia nubilalis (Lepidoptera: Crambidae) by Trichogramma brassicae (Hymenoptera: Trichogrammatidae) in three European maize-producing regions.

BACKGROUND A 2 year study was conducted to evaluate the efficacy of biological control with optimally timed Trichogramma brassicae releases as an integrated pest management tool against the European corn borer (ECB), Ostrinia nubilalis (Hübner), in on-farm experiments (i.e. real field conditions) in three European regions with dissimilar geoclimatic conditions and ECB pressure and conventional management (i.e. insecticide treated and untreated). RESULTS Biological control with Trichogramma (1) provided ECB protection comparable with conventional management, (2) in all cases maintained mycotoxin levels below the EU threshold for maize raw materials destined for food products, (3) was economically sustainable in southern France and northern Italy, but not in Slovenia where it resulted in a significant decrease in gross margin, mainly owing to the cost of Trichogramma product, and (4) enabled avoidance of detrimental environmental effects of lambda-cyhalothrin use in northern Italy. CONCLUSION Optimally timed mass release of T. brassicae could be considered a sustainable tool for IPM programmes against ECB in southern France and northern Italy. Better involvement of regional advisory services is needed for the successful dissemination and implementation of biological control. Subsidy schemes could also motivate farmers to adopt this IPM tool and compensate for high costs of Trichogramma product.

Experiences with Implementation and Adoption of Integrated Pest Management in Italy

The optimization of crop protection strategies to reduce the risk and impact of pesticides on human health and the environment began in Italy in the early 1970s. An innovative approach for crop protection was first devised through specific research programs, the involvement of farmers and financial support from the European Union (EU). A key step for integrated pest management (IPM) implementation was the application of the agroenvironmental measures (Reg. EEC no. 2078/92) that required definition of what was meant by IPM and which solutions could provide quantifiable benefits. Fundamental in that phase was the definition, in agreement with the European Union, of the principles and general criteria to be used in the implementation of IPM and the setting up of a National IPM Committee. From 1997 onwards, the National IPM Committee has been working to guarantee that the application of IPM evolves in full respect of the defined criteria. Since then IPM has spread progressively to 2 million hectares, involving 119 crops, and obtaining high implementation percentages, especially on the horticultural crops where pesticide inputs are very high. The regions have responsibility for the implementation of IPM. The system in Emilia-Romagna region is reported on, which involves more than 200 advisors as well as technical support for overseeing the implementation of IPM on around 80% of horticultural crops. Significant results have been obtained in the reduction of use of those pesticides with a high risk for human health and the environment.

Protocols for Robust Herbicide Resistance Testing in Different Weed Species.

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used. Germination methods differ according to weed species and seed dormancy type. Seedlings at similar growth stage are transplanted and maintained in the greenhouse under appropriate conditions until plants have reached the right growth stage for herbicide treatment. Accuracy is required to prepare the herbicide solution to avoid unverifiable mistakes. Other critical steps such as the application volume and spray speed are also evaluated. The advantages of this protocol, compared to others based on whole plant bioassays using one herbicide dose, are related to the higher reliability and the possibility of inferring the resistance level. Quicker and less expensive in vivo or in vitro diagnostic screening tests have been proposed (Petri dish bioassays, spectrophotometric tests), but they provide only qualitative information and their widespread use is hindered by the laborious set-up that some species may require. For routine resistance testing, the proposed whole plant bioassay can be applied at only one herbicide dose, so reducing the costs.

Integrated Pest Management policy, research and implementation: European initiatives

Times are changing for pest management in Europe. Stronger societal demands and pesticide resistance pressure farmers to reduce their reliance on pesticides more than ever before. Reconciling human health and environmental goals with production is a challenge for farmers as well as for all crop-protection stakeholders. Expectations that research and extension will quickly provide solutions are high everywhere. Although a few European countries have acquired experience with pesticide action plans or implementation of integrated pest management (IPM) guidelines on a national scale, many others are starting from a more modest base. Stakeholders in Europe are looking beyond their national borders to create synergies and share experiences and know-how. Representatives of the European Commission and Parliament, governments, research, extension, farmers, industry, and civil society are engaged in dynamic interactions. A Europe-wide structure (an ERA-Net) able to coordinate national calls for research and extension proposals on IPM is planned for 2014. Since 2007, the 10-country network ENDURE has pooled expertise among its 15 research, education, and extension member institutions. It has conducted joint reviews and original studies on IPM, organized summer schools, set up an internet-based platform on wheat cultivars and pathogens, and continues to support workshops, newsletters, and an information center with 1,600 entries for advisers. After earlier successes on insect pest management in North America or with resource-poor farmers in developing countries, Europe is set to become a source of renewed inspiration for IPM applied to conventional agriculture in industrialized countries and broadened to encompass all pest categories.

Occurrence of Different Resistance Mechanisms to Acetolactate Synthase Inhibitors in European Sorghum halepense

Four Hungarian and two Italian Sorghum halepense populations harvested in maize fields were investigated to elucidate the levels and mechanisms underlying acetolactate synthase (ALS) inhibitors resistance. The two Italian populations were highly cross-resistant to all ALS inhibitors tested, and the variant ALS allele Leu574 was identified in most of the plants; no differences were observed when the plants were treated with herbicide plus malathion. This suggests that the main resistance mechanism is target-site mediated. The Hungarian populations proved to be controlled by imazamox, while they were resistant to sulfonylureas and bispyribac-Na. All Hungarian populations, but not all plants of population 12-49H, presented the variant allele Glu376. This is the first documented occurrence of the Asp-376-Glu substitution in S. halepense. ALS enzyme bioassay and treatment with malathion confirmed that at least in plants of two populations the resistance is very likely due to both target-site and enhanced metabolism of P450 enzymes.

A “Stressed” Alfalfa-Based Cropping System Leads to the Selection of Quizalofop-Resistant Italian Ryegrass (Lolium perenne ssp. multiflorum)

Italian ryegrass populations investigated in this study were harvested in an alfalfa-based cropping system. In that system, the agronomic practices and chemical weed management, based on the use of aryloxyphenoxy-propionates herbicides (i.e., quizalofop ethyl ester), were optimized to obtain a dual seed–forage production. Five of seven populations tested were confirmed resistant to quizalofop ethyl ester with resistance indexes ranging from 4.5 to >209. Both target- and nontarget-site resistance mechanisms were most likely involved. Three allelic variants were detected (Ile-1781–Leu, Trp-2027–Cys, and Ile-2041–Asn) in four resistant populations, whereas no known mutations were found in one resistant population. The herbicide treatment on Italian ryegrass plants at different phenological stages suggested that to control regrowth, it is necessary to use two to fives times the herbicide dose suitable for younger plants. This situation is encountered in fields when Italian ryegrass plants need to be controlled to maximize the alfalfa seed production, and it is comparable to using a sublethal herbicide dose, leading to the selection of herbicide-resistant biotypes. In such a situation, the cropping system is not sustainable, and integrated weed management should be implemented to deplete the soil weed seed bank and prevent new weed seed production. Nomenclature: Quizalofop ethyl ester; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot, LOLMU; alfalfa, Medicago sativa L.