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PubMed2004

Restriction fragment length polymorphism of mitochondrial genome of the entomopathogenic fungus Beauveria bassiana reveals high intraspecific variation.

Beauveria bassiana is an entomopathogenic fungus with a growing potential for pest control in different agro-ecosystems worldwide. Such potential brings the necessity of developing a strain specific typing system. In a previous study, we reported the identification of molecular variants in mitochondrial DNA (mtDNA) polymorphism in 15 North American isolates. Results indicated a highly conserved mitochondrial genome showing only two mitochondrial genotypes (mitotypes). In this study we used whole genomic DNA from 18 isolates of B. bassiana, two unidentified Beauveria spp., and one each of B. amorpha, B. cylindrospora and B. nivea from more diverse origins. By doing single- and double-restriction enzyme digestion of total genomic DNA with EcoRI, and HindIII and then probing with BbmtE2, the predominance of mitotypes A and B was observed again, along with three newly described mitotypes (C to E). Additionally, by using whole B. bassiana mtDNA digested with HpaII as probe, we further demonstrate up to nine different mitotypes within B. bassiana. With either of the two probes, distinguished between members of the genus Beauveria and from Paecilomyces farinosus and Metarhizium anisopliae. Phylogenetic analysis could not however distinguish B. amorpha and B. nivea isolates from B. bassiana, suggesting a close genetic relation between the three species of the genus. Altogether, these results show high variability in mitochondrial genome, which can be useful as a reliable tool for the biopesticide industry for both species and isolate specific identification.

Animals↗
PubMed2002

Laboratory and field evaluation of Korean entomopathogenic nematode isolates against the oriental beetle Exomala orientalis (Coleoptera: Scarabaeidae).

The oriental beetle Exomala (Anomala) orientalis (Waterhouse) is an important pest of turfgrass in Korean golf courses, and although a few chemical insecticides are registered for insect pest control, they are not very effective against scarab larvae. There is also a growing concern in Korea about the run-off of insecticides into sensitive habitats and the potential for groundwater contamination. A safe and environmentally sound alternative is needed to conventional insecticides. We therefore evaluated six Korean entomopathogenic nematode isolates: S. carpocapsae Pocheon, S. glaseri Dongrae, S. glaseri Mungyeong, S. longicaudum Gongju, S. longicaudum Nonsan, and Heterorhabditis sp. Gyeongsan for their potential as bioinsecticides for control of E. orientalis. In addition, we evaluated a reduced chemical insecticide approach that combined chlorpyrifos-methyl with nematodes. In laboratory tests Heterorhabditis sp. Gyeongsan was the most efficacious, causing 100% mortality of the second and 38% of the third instars. All other nematode isolates caused 50-80% mortality of the second and 15-30% of the third instars. E. orientalis pupae were highly susceptible to all the Korean entomopathogenic nematode isolates except S. carpocapsae. In artificially infested field plots, all Korean nematode isolates cause 50-70% mortality of the third instar. A combination of a one-half rate of Heterorhabditis sp. and a one-half rate chlorpyrifos-methyl was synergistic, causing 91% mortality compared with 69% for the full rate of Heterorhabditis sp. or 22% for the full rate of chlorpyrifos-methyl. In a second field trial, a natural infestation of preoverwintering third instar was treated. In this trial a one-half rate of S. longicaudum Nonsan plus a one-half rate of chlorpyrifos-methyl caused 96.8% mortality, much more than a full rate of S. longicaudum Nonsan (45.9% mortality) or a full rate of chlorpyrifos-methyl (28.7% mortality). The interactions of Heterorhabditis sp. and S. longicaudum Nonsan with chlorpyrifos-methyl in our field trials appear to be synergistic.

Animals↗
PubMedDate not supplied

Distribution and leaching of methyl iodide in soil following emulated shank and drip application.

Methyl iodide (MeI) is a promising alternative to methyl bromide in soil fumigation. The pest-control efficacy and ground water contamination risks of MeI as a fumigant are highly related to its gas-phase distribution and leaching after soil application. In this study, the distribution and leaching of MeI in soil following shank injection and subsurface drip application were investigated. Methyl iodide (200 kg ha(-1)) was directly injected or drip-applied at a 20-cm depth into Arlington sandy loam (coarse-loamy, mixed, thermic Haplic Durixeralfs) columns (12-cm i.d., 70-cm height) tarped with virtually impermeable film. Concentration profiles of MeI in the soil air were monitored for 7 d. Methyl iodide diffused rapidly after soil application, and reached a 70-cm depth within 2 h. Relative to shank injection, drip application inhibited diffusion, resulting in significantly lower concentration profiles in the soil air. Seven days after MeI application, fumigated soil was uncapped, aerated for 7 d, and leached with water. Leaching of MeI was significant from the soil columns under both application methods, with concentrations of >10 mug L(-1) in the early leachate. The leaching was greater following shank injection than drip application, with an overall potential of 33 g ha(-1) for shank injection and 19 g ha(-1) for drip application. Persistent residues of MeI remaining in soils after leaching were 50 to 240 ng kg(-1), and the contents were slightly higher following shank injection than drip application. The results suggest that fumigation with MeI may pose a risk of ground water contamination in vulnerable areas.

Environmental Monitoring↗
PubMed1993

Systems of plant protection.

A framework for associating pest management with farming systems may be characterized by a cropping index (number of crop cycles per year); a plant species homogeneity rank, described as the degree of monoculture or polyculture and intensity of use of modern, high-yielding varieties versus land races or traditional varieties; intensity of use of synthetic agrochemicals; the availability of societal infrastructure to support agriculture, such as irrigation and roads; and availability of support services such as credit, public/private sector research and extension services. Traditional methods of plant protection in the tribal areas of the Philippines rely heavily on ritual-based cultural practices that recognize the crop calendar and its activities as part of a larger social agenda. Most groundnut growers in West Africa utilize minimal inputs with little infrastructural support but they have often adopted improved varieties. Extensive farming systems with modern inputs are exemplified by wheat in the mid-western USA, where pests are managed mainly through host plant resistance. In intensive farming systems--vegetables in South-East Asia, wheat in The Netherlands and orchards in the USA--crop intensification is greatest and pest problems arising from overuse of pesticides are most noticeable. Unsustainable farming systems evolve if realistic plant protection is not taken into consideration.

Agriculture↗
PubMedDate not supplied

Current United States Department of Agriculture-Agricultural Research Service research on understanding agrochemical fate and transport to prevent and mitigate adverse environmental impacts.

Environmentally and economically viable agriculture requires a variety of cultivation practices and pest management options as no one system will be appropriate for every situation. Agrochemicals are some of the many pest control tools used in an integrated approach to pest management. They are applied with the intent of maximizing efficacy while minimizing off-site movement; however, their judicious use demands a practical knowledge of their fate and effects in agricultural and natural ecosystems. Agrochemical distribution into environmental compartments is influenced by the physical and chemical properties of the agrochemical and environmental conditions, ie soil type and structure, and meteorological conditions. Agricultural Research Service (ARS) researchers working in the area of agrochemical fate have focused on accurately describing those processes that govern the transport, degradation and bioavailability of these chemicals under conditions reflecting actual agronomic practices. Results from ARS research concerning the environmental fate and effects of agrochemicals have led to the development of science-based management practices that will protect vulnerable areas of the ecosystem. The new challenge is to identify these vulnerable areas and the temporal and spatial variations prior to use of the chemical by predicting how it will behave in environmental matrices, and using that information, predict its transport and transformation within an air- or watershed. With the development of better predictive tools and GIS (Geographic Information System)-based modeling, the risks of agricultural management systems can be assessed at the watershed and basin levels, and management strategies can be identified that minimize negative environmental impacts.

Agrochemicals↗
PubMed2004

Development of a hybrid delta-endotoxin and its expression in tobacco and cotton for control of a polyphagous pest Spodoptera litura.

A hybrid delta-endotoxin protein was designed against a polyphagous lepidopteran insect pest Spodoptera litura, which is tolerant to most of the known delta-endotoxins. The hybrid delta-endotoxin was created by replacing amino acid residues 530-587 in a poorly active natural Cry1Ea protein, with a highly homologous 70 amino acid region of Cry1Ca in domain III. The truncated delta-endotoxins Cry1Ea, Cry1Ca and the hybrid protein Cry1EC accumulated in Escherichia coli to form inclusion bodies. The solubilised Cry1EC made from E. coli was 4- fold more toxic to the larvae of S. litura than Cry1Ca, the best known delta-endotoxin against Spodoptera sp. None of the two truncated toxins, solubilised from E. coli caused larval mortality. However, trypsinised Cry1Ca protoxin obtained from E. coli and solubilised from inclusion bodies caused mortality of S. litura with LC50 513 ng/ml semi synthetic diet. A synthetic gene coding for the hybrid delta-endotoxin Cry1EC was designed for high level expression in plants, taking into consideration several features found in the highly expressed plant genes. Transgenic, single copy plants of tobacco as well as cotton were developed. The selected lines expressed Cry1EC at 0.1-0.7% of soluble leaf protein. Such plants were completely resistant to S. litura and caused 100% mortality in all stages of larval development. Hence, unlike in E. coli, the hybrid delta-endotoxin folded into a functionally active conformation in both tobacco and cotton leaves. The truncated Cry1EC expressed in tobacco leaves was about 8-fold more toxic (LC50 58 ng/ml diet) compared to expression in E. coli.

Amino Acid Sequence↗
PubMed2006

Use of Bacillus thuringiensis toxins for control of the cotton pest Earias insulana (Boisd.) (Lepidoptera: Noctuidae).

Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana. At a concentration of 100 microg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 microg/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 microg/ml (for Cry9Ca and Cry1Da, respectively) for a laboratory colony originating from Spain. The relative potencies of the toxins in the population from Egypt were highest for Cry9Ca and Cry1Ab, and they were both significantly more toxic than Cry1Ac and Cry1Ba, followed by Cry1Da and finally Cry1Ia. In the population from Spain, Cry9Ca was the most toxic, followed in decreasing order by Cry1Ac and Cry1Ba, and the least toxic was Cry1Da. Binding experiments were performed to test whether the toxic Cry proteins shared binding sites in this insect. 125I-labeled Cry1Ac and Cry1Ab and biotinylated Cry1Ba, Cry1Ia, and Cry9Ca showed specific binding to the brush border membrane vesicles from E. insulana. Competition binding experiments among these toxins showed that only Cry1Ab and Cry1Ac competed for the same binding sites, indicating a high possibility that this insect may develop cross-resistance to Cry1Ab upon exposure to Cry1Ac transgenic cotton but not to the other toxins tested.

Animals↗
PubMedDate not supplied

On the safe use of pesticides in controlling the terrestrial mollusc pests.

The preferred food items of the slugs Laevicaulis alte and the snails Achatina fulica were used to prepare 'poison baits' by injecting the pesticides 'Rogor' and 'Nuvan' to kill these mollusc pests. The 'poison baits' prepared with Trichosanthes dioica and Lycopersicum esculentum were accepted by 100% individuals of both the species irrespective of the pesticides used. In all cases the slug and snail individuals died within a considerable length of time following consumption of the bait. The importance of using 'poison bait' lies not only with the sure success in killing the pests but also with the 'safe use' of toxic materials in order to avoid environmental hazards.

Animals↗
PubMed2005

Biological and biochemical studies on Biomphalaria alexandrina snails, treated with low concentrations of certain molluscicides (synthetic and of plant origin).

The effect of low concentrations of different synthetic and natural mollusciciding agents may introduce to fresh water environment on reproduction and biochemical aspects of Biomphalaria alexandrina was studied. Different mollusciciding agents (copper sulphate, Bayluscide, Uccmaluscide, Agave filifera & A. attenuate) inhibited egg production, induced marked increased the percent of abnormal laid eggs and induced marked reduction in their hatchability. The maximal reductions in egg hatchability resulted with Bayluscide (0.0%) and Uccmaluscide (18%), A. filifera (21%) and A. attenuata (15%). All the antimolluscal materials caused a successful killing effect against miracidia and cercariae of Schistosoma mansoni. CuSo4, Bayluscide and Uccmaluscide killed 40% of the exposed miracidia and 50% of cercariae after an hour exposure. The plants sublethal concentration killed 100% of cercariae and miracidia after 6 hours exposure. Water leaving behaviour among the exposed snails was noticed especially during the first three weeks, showing maximal percentage (60%) after one week of exposure to Bayluscide. A general decrease in the activity of alkaline phosphatase (ALP) especially with Bayluscide (48.4%) and in acetylcholine esterase activity in the haemolymph especially on applying plant molluscicide A. filifera (50.8%) was noticed. Transaminases showed marked elevations in activities during the 1st three weeks, then began to drop (ASAT: 61.5%, with Bayluscide & ALAT: 50.8% with Uccmaluscide). The results reflect the effect of the metabolic disorders on life, egg laying, egg hatchability, hepatic cells damages, lack of smooth transmission at nerve junction, loss of muscular coordination and convulsions, then snails' death.

Animals↗
PubMed2006

The effect of bait design on bait consumption in termites (Isoptera: Rhinotermitidae).

The efficacy of baiting as a pest control method relies on the bait appealing to the pest species. In the case of wood-eating termites, bait stations should be designed to encourage termite presence and to maximize their consumption of bait matrix in order to expedite control in minimal time. A field experiment examined the effect of bait size (one large bait or four small baits of equivalent total size, with commensurate inspection and replacement schedules), compaction (tightly rolled or loosely folded) and composition (paper only or paper plus wood) on termite presence and on untreated bait paper removal rates over four months. All three factors were significant, with bait size the most important factor, followed by compaction and then composition. The least effective baits were small, compacted (rolled) paper-only baits with monthly inspections; these had the highest abandonment rate (70%) and had the least paper removed (mean of 24 g). The most effective baits were large, folded paper-plus-wood baits with inspections at two months; these had the lowest abandonment rate (20%) and had the highest paper removal (mean of 112 g). The more than four-fold difference between these baits types demonstrates that bait efficacy can be altered considerably merely by changing bait design without adding new ingredients to the bait matrix.

Animals↗
PubMed1991

[Implications of biological pest and parasite control for environment].

Biological control of parasites, vectors and pests must consider safety to non-target organisms and to the environment. The WHO safety procedure was discussed in respect to such agents as Bacillus thuringiensis, Romanomermis culicivorax, Gambusia affinis and others. Monitoring of the environment in which biological control treatments are performed is necessary to secure safety requirements as well as the efficiency of biological control programmes.

Environmental Monitoring↗
PubMed1992

Family pesticide use in the home, garden, orchard, and yard.

This study examined family use of pesticides in the home, garden, orchard, and yard. Data were collected from 238 families in Missouri during telephone interviews from June 1989 to March 1990. Nearly all families (97.8%) used pesticides at least one time per year and two thirds used pesticides more than five times per year. More than 80% used pesticides during pregnancy and 70% used pesticides during the first 6 months of a child's life. The most common setting for family pesticide use was in the home, where 80% of families used pesticides at least once per year. This was followed by herbicide use to control yard weeds (57% of families) and insecticide use to control fleas and ticks on pets (50% of families). A substantial number of families also used pesticides in the garden or orchard (33%). Flea collars were the most popular pest control product (50% of families). Carbaryl or Sevin was also popular, with 28.2% of families reporting use. No-pest-strips (dichlorvos) and Kwell shampoo (lindane) were used by almost 10% of participating families. Examination of study data revealed that families limited exposure to pesticides for the mother during pregnancy and for children during the first 6 months of life. Families failed to recognize and reduce pervasive exposures associated with no-pest-strips and flea collars.

Animals↗
PubMed1983

Biological control of insect pests.

Isozyme techniques have proven particularly useful in the past in the field of biological insect control. In this brief review I have tried to give a small selection of the varied approaches that have been used. In the future, isozyme analysis will undoubtedly play a major role. But genetic analyses, as exemplified by the use of isozymes, form but a small part of the knowledge we must have if biological control programs are to be successful. In a pest management program where one is using both chemical and biological methods it is necessary to know a great deal about the biology of the pests, their parasites, predators, and host plants or animals, together with a knowledge of the general ecology of the area where the problem exists. Too often, major control programs have been started with pitifully inadequate basic knowledge of the insect pest concerned, dooming such projects to a series of frantic and generally makeshift attempts to redeem these inadequacies. We are starting to see a much greater emphasis on interrelationships between scientific disciplines, more basic research being conducted, and a resurgence of interaction between those people who are in the applied field and those in the basic sciences. This dialog must be continued. In closing, I want to emphasize again that in pest control we are involved in the management of a coexistence with insects and I think it appropriate to end with the thoughts of W.J. Holland [1949]: when all cities shall have been long dead and crumbled into dust, and all life shall be on the very last verge of extinction on this globe; then on a bit of lichen, growing on the bald rocks beside the eternal snows of Panama, shall be seated a tiny insect, preening its antenna in the glow of the worn-out sun, representing the sole survival of animal life on this our earth--a melancholy 'bug'.

Alleles↗