Biological control of water hyacinth – the South African experience1

Water hyacinth remains one of the worst aquatic weeds worldwide, and its presence in South Africa since the early twentieth century prompted research into biological control options. The first control agent released in South Africa was the weevil Neochetina eichhorniae in 1974, but the project was terminated three years later, and resumed in 1985. Since then, five arthropod biocontrol agents have been released in South Africa, more than anywhere else in the world, including another weevil, N. bruchi, a moth, Niphograpta albiguttalis, a mite, Orthogalumna terebrantis and a mirid, Eccritotarsus catarinensis. To date, the success of biological control of water hyacinth in South Africa has been variable, and this has been ascribed to, amongst other factors, climatic incompatibility of control agents, and eutrophication of water hyacinth impoundments. Successful control is achieved in warm subtropical sites which are not affected by frost in winter, and in water bodies that are not heavily polluted with nitrates and phosphates. The biocontrol programme is the result of collaborative research with scientists from the USA, Australia and Argentina, and the experience obtained and lessons learned in these regions and South Africa can be used to initiate a biocontrol programme in Europe.     

Western flower thrips (Frankliniella occidentalis)—occurrence and possibilities for its control in Hungary1

Frankliniella occidentalis was first recorded in Hungary in 1989. The pest has endangered the mass-rearing and distribution of the biological control agents Encarsia formosa and Phytoseiulus persimilis being conducted at the Hódmezövásárhely Institute. Different insecticide active ingredients were studied for elimination of the pest from experimental glasshouses and new methods for monitoring populations of the new thrips. The fungus Verticillium lecanii has been tested as an indirect control agent.     

Registration of biological pesticides — the UK perspective1

The approaches that have been used for regulation of biological pesticides in the UK to date are discussed in relation to the expected European system. Biological pesticides are defined under the Control of Pesticides Regulations 1986 as ‘bacteria, protozoa, fungi, viruses and mycoplasmas used for destroying or controlling pests’. The data requirements for biological pesticides are simpler than those for chemical pesticides but take into account special factors such as infectivity, sensitization of users and toxin production. The Plant Protection Products Regulations (1995) implement Directive 91/414/EEC in the UK.     

Biological control and plant health in the UK1

The protected crop environment has long been recognized as offering particularly good opportunities for the application of biological control and this is reflected in the predominance of integrated pest management programmes and the wide range of biological control agents available. The introduction of new pest species of quarantine concern can often occur in glasshouse crops, as a result of international trade in plant material, and can have a highly disruptive impact upon well established, integrated pest management programmes. The use of biological control agents against quarantine pests is discussed, including both the use of exotic species and those established in the UK. The relevant legislation in the UK is outlined in relation to the introduction of non-native species, including both plant protection and conservation interests. Environmental safety aspects such as the impact of such introductions on non-target species and issues of quality control to prevent the introduction of contaminants are noted as of particular plant health interest.     

PRO_PLANT—a computer—based decision-support system for cereal disease control1

The task of the knowledge-based advisory system PRO_PLANT is to help farmers reduce to a minimum the input of fungicides, and in later stages all pesticides, while giving as good economic returns as high-input routine sprays with their potential environmental hazards (e.g. ground and surface water contamination). The system was first developed for cereal diseases and is now (till 1994) being extended to the most important pesticide applications on field crops (cereals, maize, rape, potato, sugarbeet). It can be used by consultants or farmers as a stand-alone version. PRO_PLANT at present consists mainly of disease-specific knowledge bases for diagnosis of fungus infections in cereals and rules for optimized fungicide treatments. The scientific basis has been derived from expert knowledge and field trials over several years, and the knowledge representation is rule-based. During a consultation, information on the field, cultivar resistance, seed treatments and fungicides is considered. Necessary weather data comes from the German Weather Service via BTX or from a small home-run weather station. The prototype was first tested in 1991 and an improved version was then tested in 1992 with 40 consultants and 30 farmers. In 1993, the system will be used by the advisory service of Nordrhein-Westfalen and commercially distributed to farmers.     

Biopesticides — harmonization of registration requirements within EU Directive 91/414 — an industry view1

A range of biopesticides (including, as active substances, bacteria, viruses, fungi, nematodes, protozoa and beneficial insects) is now commercially available for control of insect pests, fungal and bacterial diseases and weeds. The term biopesticide can include pheromones, insect and plant growth regulators, plant extracts, transgenic plants and macroorganisms as well as microorganisms. However, world biopesticide sales in 1990 were estimated to be 120 million USD, representing less than 0.5% of the world's agrochemical market. Out of this, approximately 90% of the biopesticide sales are represented by the bacterium Bacillus thuringiensis for the control of insect pests. Nevertheless, biopesticide sales are estimated to be increasing at 10–25% per annum and sales by the year 2000 are estimated to reach 1000 million USD. This paper looks at the current commercial status and the constraints that are facing industry concerning changing registration, particularly in Europe, the absence of harmonized data requirements, and the increasing costs and delays in registrations that deter the development of new biopesticides.     

Biological control of weeds in European crops: recent achievements and future work

Approaches to the biological control of weeds in arable crops and integration of biological weed control with other methods of weed management are broadly discussed. Various types of integrative approaches to biological control of weeds in crops have been studied within the framework of a concerted European Research Programme (COST‐816). During the period 1994–99, some 25 institutions from 16 countries have concentrated on five target weed complexes. Some major scientific achievements of COST‐816 are: (i) combination of the pathogen Ascochyta caulina with an isolated phytotoxin produced by this fungus to control Chenopodium album in maize and sugar beet; (ii) the elaboration and preliminary field application of a system management approach using the weed:pathogen system Senecio vulgaris:Puccinia lagenophorae to reduce the competitiveness of the weed by inducing and stimulating a disease epidemic; (iii) combination of underseeded green cover with the application of spores of Stagonospora convolvuli to control Convolvulus species in maize; (iv) assessment of the response of different provenances of Amaranthus spp. to infection by Alternaria alternata and Trematophoma lignicola, the development of formulation and delivery techniques and a field survey of native insect species to control Amaranthus spp. in sugar beet and maize; (v) isolation of strains of different Fusarium spp. that infect all the economically important Orobanche spp. and development of novel, storable formulations using mycelia from liquid culture. Although no practical control has yet been reached for any of the five target weeds, potential solutions have been clearly identified. Two major routes may be followed in future work. The first is a technological approach focusing on a single, highly destructive disease cycle of the control agent and optimizing the efficacy and specificity of the agent. The second is an ecological approach based on a better understanding of the interactions among the crop, the weed, the natural antagonist and the environment, which must be managed in order to maximize the spread and impact of an indigenous antagonist on the weed.     

Methods of controlling Tomato yellow leaf curl virus (TYLCV) and its vector Bemisia tabaci in the Maltese Islands*

Bemisia tabaci and Tomato yellow leaf curl virus (TYLCV) were first observed in Malta in the early 1990s and caused serious damage to glasshouse and outdoor tomato crops. Chemical, physical and biological control methods have been developed, but the effective method has been the use of virus‐tolerant cultivars.     

Biological control in Hungary: present situation and possibilities1

Biological control has already achieved certain results in Hungary, especially against soil-borne fungi and glasshouse pests. Nevertheless, experience has shown that locally found biological agents, however effective, could not be developed into registered, ready-for-sale plant protection products because of the lack of companies willing to invest. Biological control in Hungary is therefore limited to the conservation of natural antagonistic flora and fauna and to the application of imported biopesticides and bioagents, which are subject in Hungary to a registration procedure similar to that for chemical plant protection products. Current work includes the development of an anti-nematode product from a local strain of Arthrobotrys oligospora, application techniques for a local mirid Dicyphus hyalinipennis against insect pests, studies with native and imported strains of the nematodes Steinernema and Heterorhabditis against soil-borne insect pests, and introduction techniques for the chrysomelid Zygogramma sutularis against the weed Ambrosia elatior.     

Biological control in protected strawberry in northern Italy1

Biological control is currently being used in 100 ha of tunnel-grown strawberry in northern Italy. Second-instar larvae of Chrysoperla carnea are released (18 larvae per m²) against aphids when more than 30% of leaflets are infested. Releases of Phytoseiulus persimilis (4–6 predatory mites per m²) are also being used in IPM strategies against Tetranychus urticae; wild P. persimilis populations also occur in the test area, which is near the Adriatic coast. Releases of predators are also successful in the field.     

Two years of trials with biological control programmes in all -year-round chrysanthemums1

In trials conducted in 1989 and 1990 in Kent and Worcestershire (England), an IPM programme for the range of pests of chrysanthemums was evaluated. The main target pest was Frankliniella occidentalis but biocontrols for Trialeurodes vaporariorum, aphids (mainly Myzus persicae) and Tetranychus urticae were also used. Anthocoris nemorum adults and nymphs collected from the wild gave good control of F. occidentalis in Kent in 1989 at the rate of 1 per 10 m₂ per week. In 1990 trials, A. nemorum also gave good thrips control at 1 per 20 m₂ per week, providing that thrips numbers were low at the start of the trial. Anthocorids also preyed on aphids, spider mites and whitefly scales. Lygocoris pabulinus was not affected by A. nemorum and caused some flower damage in the IPM trial. In the 1990 trial in Worcestershire, a combination of Verticillium lecanii (Mycotal) weekly sprays at 1 g litre^?1 of water and Neoseiulus cucumeris predators applied weekly at 50 per m₂ also gave good control of F. occidentalis. Conditions for the use of Mycotal were excellent, with humidity in the crop normally above 85% once the blackout screens were drawn. The effect of Mycotal was seen within 2 weeks on the whitefly population, as many infected adults and scales were found. No infected thrips were seen at any time, but it is thought that the Mycotal did have a significant effect upon the thrips population. N. cucumeris (Thripex-Koppert) did not establish well on chrysanthemums when applied in bran from a shaker bottle. However, this predator may establish in larger numbers when slow-release bags are used. Further work on this aspect is needed. The commercial availability of predatory bugs such as anthocorids or Orius spp. would undoubtedly increase the uptake of IPM methods by growers.     

Pesticidal natural products – status and future potential

There is a long history of using natural products as the basis for creating new pesticides but there is still a relatively low percentage of naturally derived pesticides relative to the number of pharmaceuticals derived from natural sources. Biopesticides as defined and regulated by the US Environmental Protection Agency (EPA) have been around for 70 years, starting with Bacillus thuringiensis, but they are experiencing rapid growth as the products have got better and more science‐based, and there are more restrictions on synthetic chemical pesticides. As such, biopesticides are still a small percentage (approximately US$3–4 billion) of the US$61.3 billion pesticide market. The growth of biopesticides is projected to outpace that of chemical pesticides, with compounded annual growth rates of between 10% and 20%. When integrated into crop production and pest management programs, biopesticides offer the potential for higher crop yields and quality than chemical‐only programs. Added benefits include reduction or elimination of chemical residues, therefore easing export, enabling delay in the development of resistance by pests and pathogens to chemicals and shorter field re‐entry, biodegradability and production using agricultural raw materials versus fossil fuels, and low risk to non‐target organisms, including pollinators. Challenges to the adoption of biopesticides include lack of awareness and education in how to deploy their unique modes of action in integrated programs, testing products alone versus in integrated programs, and lingering perceptions of cost and efficacy. © 2019 Society of Chemical Industry     

Biological control of pests in Swedish pot plant production1

Biological control of glasshouse pests is nowadays an important factor in the production of pot plants in Sweden. During 1990, more than 100 growers applied one or more methods of biocontrol, some only in propagation units but many during the entire production of several crops. Poinsettia is the major crop in this context. Eighty growers were interviewed about their experiences of various biocontrol methods. The use of Neoaplectana carpocapsae against sciarids and Otiorhynchus sulcurus was the most popular and reliable method. Next comes Encarsia formosa against whiteflies. Other methods include Verticillium lecanii against whiteflies and thrips, Aphidius matricariae against aphids, and predatory mites against thrips and spider mites.     

Quantification of biopesticide activity — a rapid survey of methods and standardization problems1

Worldwide development of IPM techniques and increased interest in microbial pesticides have brought a wide range of registered products onto the market in many countries. Quality control is the key point for manufacturing companies because of the variable biological nature of the products and constraints concerning their storage life. The technical specifications of such microorganism-based preparations are rather difficult for end users to understand and there is an urgent need for standardization. The European Committee for Standardization (ECS) has set up a working group to prepare standard guidelines on assessment of the purity, biological activity and stability of microorganism-based preparations. This paper discusses the measurement of the activity of the three main classes of frequently used microbial pesticides, those of bacterial origin (Bacillus thuringiensis toxin), viral products (insect baculovirus) and fungal products (antagonistic or entomopathogenic).     

Biological control of exotic pests in Italy: recent experiences and perspectives1

In Italy, successful application of classical biological control began in the 20th century, when Berlese released the predator Rodolia cardinalis in 1901 and the parasitoid Encarsia berlesei in 1906. Later, the ‘inoculative’ method was applied many times, limiting the misuse of insecticides and therefore achieving very positive effects for both the agricultural economy and environmental protection. When the establishment of new natural enemies failed, some exotic pests continued to damage important crops, sometimes disrupting any possibility of applying Integrated Pest Management (IPM). In other cases, new associations between exotic pests and native natural enemies occurred spontaneously and the importation of new species was not necessary: when no broad-spectrum plant protection products are applied, some palaearctic parasitoids, such as Diglyphus isaea, naturally control the imported American leafminers Liriomyza trifolii and L. huidobrensis and some native predators (mainly Orius spp.) often control the exotic western flower thrips Frankliniella occidentalis. However, the introduction of natural enemies from the area of origin of the exotic pest is often the only alternative to chemical insecticides. Since its introduction in 1979, the American Flatid, Metcalfa pruinosa, has been spreading annually into new areas of the Mediterranean, causing severe damage to many crops because none of the indigenous natural enemies are sufficiently effective. Therefore, only the introduction of exotic natural enemies, such as the parasitoid Neodryinus typhlocybae, may reduce the outbreaks.     

Biological control of botrytis bunch rot in organic wine grapes with the yeast antagonist Candida sake CPA‐1

The aim of this research was to confirm the efficacy of the yeast antagonist Candida sake CPA‐1 in suppressing botrytis bunch rot development, in an organic vineyard under Mediterranean conditions for two seasons, and compare its performance with that of two biologically based products currently registered for botrytis bunch rot control in New Zealand. In 2009, treatments applied were: commercial formulations of Ulocladium oudemansii (BOTRY‐Zen^®) and chitosan (ARMOUR‐Zen^®), C. sake CPA‐1 combined with the fatty acid‐based additive Fungicover^® and combinations of these products. All treatments were applied six times between early flowering and harvest and compared with an unsprayed control. In 2010, the treatments focused on C. sake and Fungicover and the number of applications was reduced from six to four. The population dynamics of U. oudemansii and C. sake were measured and wine quality tests were carried out in both seasons. Disease control achieved by C. sake treatments in 2009 were comparable to those achieved by BOTRY‐Zen and ARMOUR‐Zen. Applications of C. sake plus Fungicover between flowering and harvest significantly (P < 0·05) reduced botrytis bunch rot incidence and severity by 64% and 90%, respectively, compared with the untreated control in 2009, and by 67% and 89%, respectively, in 2010. Treatments did not adversely affect wine quality parameters after treated grapes were processed. Candida sake consistently provided effective control of botrytis bunch rot in grapes under different meteorological and disease pressure conditions, thereby improving its potential for future commercial applications.     

Inheritance of fenvalerate and carbofuran resistance in colorado beetles—Leptinotarsa decemlineata (Say)—from North Carolina

Progeny from reciprocal F1 crosses and F1 backcrosses between fenvalerate-resistant and fenvalerate-susceptible Colorado beetles, Leptinotarsa decemlineata (Say), and between carbofuran-resistant and carbofuran-susceptible Colorado beetles were bioassayed to investigate the mode of inheritance of resistance to these chemicals. Bioassays of progeny from these crosses indicate that resistance to fenvalerate is inherited in a semi-recessive, sex-linked manner and carbofuran resistance is inherited in a partially dominant autosomal fashion. Log concentration/probit mortality lines and chi-square tests, however, indicate that multiple genes may be involved in resistance to both insecticides.