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PubMed1985

Estimated risks and benefits from introducing Marisa cornuarietis into the Sudan.

As it has been proposed that Marisa cornuarietis, the ampullarid snail from the tropical Americas be used in the Sudan as a biological control agent against schistosomiasis, an estimate was made of the potential ecological hazards which might result from its widespread distribution in the Nile River Valley, and also of the potential benefits. The only foreseeable hazard would result from colonization of rice fields by the ampullarid snail and subsequent crop damage. However calculations on population dynamics indicated that Marisa cornuarietis would not be able to establish significant populations in rice fields in the Nile Valley as the flooded periods are too short. Thus the expected benefits of schistosomiasis control far outweigh any expected risks, and the ampullarid should be used in expanded field trials in the Gezira Irrigated Area as a control method for schistosomiasis.

Agriculture↗
PubMed2001

Genetics, biotechnology and population management of over-abundant mammalian wildlife in Australasia.

Wildlife management involves regulation of population numbers of wild vertebrate species. In some cases there are too many animals and in others there are too few. Genetic issues arise in both instances. The historical and genetic evidence for the number of mammals that were in the founder populations of successful colonizing species in Australia and New Zealand is reviewed here. Small numbers have often given rise to large populations, despite the concomitant loss of genetic variability. Restriction of the number of over-abundant and pest species by either physical or chemical methods frequently constitutes very strong artificial selection, which leads to rapid genetic change; an example of major importance in the two countries is sodium monofluoroacetate (compound 1080). Pathogenic agents, surgical sterilization, hormonal contraceptives and translocation have all been used with varying degrees of success. The strengths and weaknesses of these techniques are assessed. A method that has received much attention is immunocontraception. We argue that this attempt to use the animals' own immune system to modulate reproduction is incompatible with the basic biological function of protection against infectious disease. Immune function genes are highly variable in vertebrates, and so often genetic change in the population subjected to immunocontraception is likely to be even more rapid than is the case with lethal agents. Selection for failure to respond to the immunocontraceptive will occur, and will change immune function in general. Poor scientific description of ecosystem complexity makes it difficult to predict the consequences of immunocontraception on wildlife populations.

Animals↗
PubMed2006

Biological control of Indianmeal moth (Lepidoptera: Pyralidae) on finished stored products using egg and larval parasitoids.

Biological control using hymenopteran parasitoids presents an attractive alternative to insecticides for reducing infestations and damage from the Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), in retail and warehouse environments. We examined the potential for using combinations of the egg parasitoid Trichogramma deion Riley (Hymenoptera: Trichogrammatidae), and the larval parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) for preventing infestations of P. interpunctella in coarse-ground cornmeal as well as the influence of packaging on parasitoid effectiveness. Treatments included one or both parasitoids and either cornmeal infested with P. interpunctella eggs or eggs deposited on the surface of plastic bags containing cornmeal. H. hebetor had a significant impact on the number of live P. interpunctella, suppressing populations by approximately 71% in both unbagged and bagged cornmeal. In contrast, T. deion did not suppress P. interpunctella in unbagged cornmeal. However, when released on bagged cornmeal, T. deion significantly increased the level of pest suppression (87%) over bagging alone (15%). When H. hebetor was added to bagged cornmeal, there was a significant reduction of live P. interpunctella compared with the control (70.6%), with a further reduction observed when T. deion was added (96.7%). These findings suggest that, in most situations, a combined release of both T. deion and H. hebetor would have the greatest impact; because even though packaging may protect most of the stored products, there are usually areas in the storage landscape where poor sanitation is present.

Animals↗
PubMed1998

Monitoring the spread of rabbit hemorrhagic disease virus as a new biological agent for control of wild European rabbits in Australia.

Following the escape to the mainland of the rabbit hemorrhagic disease virus (RHDV) from Wardang Island off the coast of South Australia, a monitoring program was implemented over a 13 mo period, between October 1995 and October 1996 to determine the activity and rate of spread of the disease in the wild European rabbit (Oryctolagus cuniculus) population. All reports of dead rabbits were investigated. Whenever possible, liver and spleen tissue samples were collected from fresh carcasses and subsequently analysed for the presence of RHDV. Maximum rates of spread of rabbit hemorrhagic disease (RHD) in Australia ranged from 9 km/mo during summer to 414 km/mo in spring. New cases of RHD were moderate during late autumn and winter and peaked in spring. In summer the disease was rarely reported.

Analysis of Variance↗
PubMed2005

Osmotically induced trehalose and glycine betaine accumulation improves tolerance to desiccation, survival and efficacy of the postharvest biocontrol agent Pantoea agglomerans EPS125.

The application of the biocontrol agent Pantoea agglomerans EPS125 to unwounded fruits was practically ineffective for control of postharvest blue mould caused by Penicillium expansum when the treatment and subsequent wounding and pathogen inoculation were separated by periods of unfavourable conditions. This was due to a rapid decrease in viability of the alocthonous introduced biocontrol agent in the intact peel surface. A system for osmoadaptation of the biocontrol agent was developed by combining saline osmotic stress and osmolyte amendment to the growth medium. Osmoadapted cells accumulated trehalose and glycine betaine (GB) intracellularly and showed a higher tolerance to desiccation than non-osmoadapted cells. Osmoadaptation in NaCl plus GB during inoculum preparation increased considerably survival on the peel surface of apple fruits. This effect was significant under low relative humidity (RH) and fluctuating RH conditions, but was not significant at high RH. Osmoadaptation significantly improved blue mould control under conditions where the standard biological control treatments were ineffective. The rot diameter was significantly reduced in apple fruits which were treated with EPS125 and incubated for several days under low, high or fluctuating RH, followed by wounding and inoculation of P. expansum. Growth of EPS125 with NaCl, either with or without the addition of GB, was an effective osmoadaptation treatment for improving blue mould rot control. However, the addition of GB to the NaCl amended growth medium increased 4-5-fold growth rate and OD of the cultures. This is an advantage for mass production of P. agglomerans EPS125 in a NaCl amended growth medium.

Adaptation, Physiological↗
PubMed2003

Enhancement of the efficacy of a combination of Mesocyclops aspericornis and Bacillus thuringiensis var. israelensis by community-based products in controlling Aedes aegypti larvae in Thailand.

Prolonged efficacy of a combination of bacteria (Bacillus thuringiensis var. israelensis [Bti] and copepods (Mesocyclops aspericornis) in controlling immature forms of Aedes aegypti in peridomestic water containers was achieved by adding various products from local villages as supplementary food for copepods. In all experiments, 100 first-instar larvae were added into the breeding containers every day for eight weeks. Combinations of biological control agents and each local supplementary food were applied once at the beginning of the experiment. At the end of the experiment, the average number of mosquito larvae in containers with a combination of copepods and Bti with one gram of rice grain had decreased to only 0.5% of that with no control agent. In comparison, the average numbers of mosquito larvae in containers with Bti only, or copepods only, were approximately 10% and 33% of those in containers with no control agents, respectively. In addition, the number of copepods in containers with mosquito larvae and supplementary food was at least three times higher than those with mosquito larvae alone.

Aedes↗
PubMed2005

Using worms to better understand how Bacillus thuringiensis kills insects.

Bacillus thuringiensis is widely used as a biological pesticide to control insects that either cause damage to crops or transmit disease. That it can also target the model organism Caenorhabditis elegans has not only provided exciting new insights into how the toxins produced by the bacterium target their victims but also how target insects counter the attack. Modern approaches such as reverse genetics and microarray technology have revealed novel receptors for the toxins and possible signal transduction pathways induced within the host following intoxication. This article will discuss how these findings fit in with current models and how they might influence future studies.

Animals↗
PubMed2000

The influence of Bacillus sphaericus on the biology and histology of Phlebotomus papatasi.

This work was achieved to study the impact of B. sphaericus treatment on some biological aspects of P. papatasi. Contaminated larval food with B. sphaericus (strain-2362) in different concentrations was offered in the laboratory for P. papatasi and also the latent effect on the fecundity of survived females from previously treated larvae. There was a decrease in the survived numbers of immature stages and adults correlated to the concentrations, while there was no obvious change in the larval and pupal durations compared to the control. The fecundity of females survived from previously treated larvae, was sharply decreased. Many variations was noticed in the examined tissues of mid-gut, fat tissues, and Malpighian tubules, although no bacteraemia was detected.

Animals↗
PubMed1999

Biological control of nematode parasites of livestock in Fiji: screening of fresh dung of small ruminants for the presence of nematophagous fungi.

Approximately 2500 faecal samples were collected per rectum from sheep and goats from 26 farms located on four of the Fijian islands where most of the small ruminants in this country are raised. The purpose was to screen these samples to isolate nematode-trapping fungi that had been acquired by these animals during the course of their feeding and which had remained viable following passage through their gastrointestinal tract. From these samples, 23 examples of nematophagous fungi were noted in the initial appraisal, from which 12 pure isolates (all of the genus Arthrobotrys) were made. A number factors emerged from this work which may have restricted the opportunities in which nematophagous fungi were detected, or isolated.

Animals↗
PubMedDate not supplied

[Morphological and histological comparison of the digestive tract of Gambusia puncticulata and Girardinus metallicus, fishes used in the biological control of mosquitoes].

The morphology and histology of the digestive tract of Gambusia puncticulata and Girardinus metallicus fishes used in the biological control of mosquito larvae in Cuba, were described and compared. They were related to the food habits of each species. Gambusia puncticulata has a short and thick intestine, which is characteristic of the carnivorous species, whereas Girardinus metallicus has an elongate and thin spiral rolled up intestine as it corresponds to the omnivorous fishes. It was observed that the histological pattern of the intestine in both species is very simple; however, Gambusia puncticulata presented a great number of ramified microhairiness on comparing it with Girardinus metallicus, which increases this way the digestive yield of its relatively shorter digestive tract.

Animals↗
PubMed2003

Screening of antagonistic bacteria for biological control of nursery wilt of black pepper (Piper nigrum).

Bacterial antagonists of Phytophthora capsici were isolated from underground shoot portions of rooted cuttings of black pepper. Initially isolates were screened by dual culture on potato dextrose agar and carrot agar. Further, a screening was done on black pepper shoots for supression of lesion caused by the pathogen. Most of the antagonists showed varying levels of antagonism in the dual culture and the shoot assay. Isolate PN-026, showing the highest suppression of lesion development in the shoot assay was found to be the most efficient antagonist in reducing Phytophthora capsici induced nursery wilt of black pepper. This screening involving the host, pathogen, and the antagonist, performed on black pepper shoot (the planting material for this vegetatively propagated crop), could be used as a rapid and reliable method for the isolation of efficient bacterial antagonists of P. capsici.

Antibiosis↗
PubMedDate not supplied

Baculovirus and insect cell gene expression: review of baculovirus biotechnology.

The BEVS continues to evolve as a powerful, flexible tool for molecular biology, protein function, and biomedical research. Future developments offer the promise of replacement of hazardous chemical insecticides with environmentally safe biopesticides, construction of baculovirus vectors which encode genes for specific post-translational modifications, and establishment of efficient, stably transformed insect cell lines. FDA approval of BEVS-produced products offer the prospect of new biopharmaceuticals, in particular human therapeutics and vaccines, to improve human health and increase the quality of life for millions of people.

Animals↗
PubMed2001

Expression of mosquito active toxin genes by a Colombian native strain of the gram-negative bacterium Asticcacaulis excentricus.

Mosquito control with biological insecticides, such as Bacillus sp. toxins, has been used widely in many countries. However, rapid sedimentation away from the mosquito larvae feeding zone causes a low residual effect. In order to overcome this problem, it has been proposed to clone the Bacillus toxin genes in aquatic bacteria which are able to live in the upper part of the water column. Two strains of Asticcacaulis excentricus were chosen to introduce the B. sphaericus binary toxin gene and B. thuringiensis subsp. medellin cry11Bb gene cloned in suitable vectors. In feeding experiments with these aquatic bacteria, it was shown that Culex quinquefasciatus, Aedes aegypti, and Anopheles albimanus larvae were able to survive on a diet based on this wild bacterium. A. excentricus recombinant strains were able to express both genes, but the recombinant strain expressing the B. sphaericus binary toxin was toxic to mosquito larvae. Crude protease A. excentricus extracts did not degrade the Cry11Bb toxin. The flotability studies indicated that the recombinant A. excentricus strains remained in the upper part of the water column longer than the wild type Bacillus strains.

Animals↗
PubMed2006

Prospects for the mosquito baculovirus CuniNPV as a tool for mosquito control.

CuniNPV is a pathogen of Culex mosquitoes, vectors of West Nile virus and other forms of encephalitis. Successful development of CuniNPV requires an efficient production system and formulated product that incorporates magnesium, an essential component for transmission. It may be possible to develop mosquito baculoviruses as a new type of biopesticide by microencapsulating the virus and magnesium into formulations that would be effective regardless of the water quality. In addition, this new insight on transmission may facilitate the discovery and development of additional baculoviruses for the control of other important mosquito vectors. Biological mining of the CuniNPV genome and investigations to understand virus-mosquito interactions at the molecular level offer exciting possibilities for the development of novel mosquito control strategies and tools. Understanding the molecular mechanisms of infection will provide the opportunity to devise new control strategies, for example, compromising the defensive systems of the mosquito (proteases for the peritrophic matrix) or exploiting receptors used by the virus to specifically deliver toxins to mosquito larvae via the midgut. As additional baculovirus genomes become available, comparative genomics could lead to a more informed understanding of how the virus exploits its host as well as the factors responsible for the genus-specific host range of most known mosquito baculoviruses.

Animals↗
PubMed1990

Biological control of Biomphalaria glabrata by Thiara granifera under laboratory conditions.

The effect of the snail Thiara granifera on the snail Biomphalaria glabrata, intermediate host of Schistosoma mansoni in the Dominican Republic, was evaluated. Plastic aquaria, 3 and 1.5 gallons in capacity, were used. The aquaria were either unpartitioned or partitioned by a fine screen into two equal compartments, and the two snail species were introduced in different proportions. The results over a 1-year period showed that T. granifera effectively reduced the fecundity of B. glabrata, especially when the initial densitites of the two species were equal or where T. granifera was more abundant. There was still competition, although starting at a later date, when the density of T. granifera was half that of B. glabrata. The competitive interaction does not seem to be due to competition for food but to a chemical factor(s), possibly water-soluble pheromones.

Analysis of Variance↗
PubMed2005

Selective feeding of tobacco budworm and bollworm (Lepidoptera: Noctuidae) on meridic diet with different concentrations of Bacillus thuringiensis proteins.

Laboratory experiments were conducted to evaluate the behavior of bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), larvae on meridic diet with different concentrations of the Cry1Ac and Cry2Ab proteins from Bacillus thuringiensis subsp. kurstaki Berliner. The proteins used in these experiments are the ones in commercially available Bollgard and Bollgard II cotton. Both bollworms and tobacco budworms selectively fed on nontreated diet compared with diet treated with Cry1Ac. In addition, bollworms exhibited a concentration response with Cry1Ac. In general, bollworms selected diet with low concentrations of Cry1Ac compared with diet with higher concentrations of Cry1Ac. For Cry2Ab, the avoidance was not as prominent as that observed for Cry1Ac. Based on results from no-choice assays, the Cry1Ac and Cry2Ab concentrations used in choice assays represented a wide range of biological activity on both species. The lower concentrations provided low levels of mortality, whereas the higher concentrations provided high levels of mortality. Also, the developmental times of larvae were longer at higher concentrations of both proteins. These data provide important information about the behavioral response of key cotton pests to the B. thuringiensis proteins found in commercially available transgenic cotton. This information will be important to develop accurate scouting and management procedures for Bollgard and Bollgard II cotton.

Animals↗
PubMed2005

Contribution of phlA and some metabolites of fluorescent pseudomonads to antifungal activity.

Fluorescent Pseudomonas species are an important group of PGPR that suppress fungal root and seedling disease by production of antifungal metabolites such as 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin, pyrolinitrin, siderophores and HCN. The compound 2,4-DAPG is a major determinant in biocontrol of plant pathogens. A 7.2 kbp chromosomal DNA region, carrying DAPG biosynthetic genes (phlA, phlC, phlB, phlD, phIE and phlF). Detecting the ph1 genes make them an ideal marker gene for 2,4-DAPG-producing fluorescent pseudomonad's. In this study we detected ph1A gene (that convert MAPG to 2,4-DAPG) using PCR assay with primers phlA-1r and phlA- f that enabled amplification of phlA sequences from fluorescent pseudomonad's from ARDRA group 1 and 3. We could detect phlA gene in P. fluorescens strains CHAO, Pf-44, Pf-1, Pf-2, Pf-3, Pf-17, Pf-62 and Pf-64, native isolates of Iran. The efficacy of this method for rapid assay characterizing rhizosphere population of 2,4-DAPG producing bacteria from soil of different area of Iran is in progress. We used a collection of 48 fluorescent pseudomonas strains in vitro, with known biological control activity against some soil born phytopathogenic fungi such as, Macrophomina phaseoli, Rhizoctonia solani Vericillium dahlia, Phytophthora nicotiana, Pythium spp. and Fusarium spp. and the potential to produce known secondary metabolites such as protease. Strains Pf-1, Pf-2, Pf-3, Pf-17, Pf-33 and Pf-44 showed the best antifungal activity against all fungi used in this study. Thirty-eight of 48 strains produced protease. The ability to rapidly characterize populations of 2,4-DAPG producers will greatly enhance our understanding of their role in the suppression of root disease.

Antibiosis↗
PubMed1997

Susceptibility of immature Ixodes scapularis (Acari:Ixodidae) to plant-derived acaricides.

Plant-derived acaricides, extracted from various botanical species, and commercially available phytochemicals were evaluated for biological activity against immature Ixodes scapularis (Say) using the disposable pipet method. In addition, residual activity of the plant extracts was determined. Of the 13 plant extracts tested, 9 exhibited biological activity with Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach., being the most effective against the nymphal ticks (LC50 = 0.151% wt:vol) and eastern red cedar, Juniperus virginiana L., showing the greatest activity against larval ticks (LC50 = .001% wt:vol). The commercially available products were significantly less active than the plant extracts we prepared, but some commercial compounds did exhibit limited activity. Only the Alaska yellow cedar exhibited any residual activity that lasted 21 d after treatment.

Animals↗