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At least 1,315 records · Page 73Linked to original sources
PubMed1980

[Glossina, domestic livestock and wild fauna: is a conciliation possible?].

Animal trypanosomiasis is one of the major obstacles to livestock production in Africa. South of the Sahara. Tsetse fly control is considered to be the best method of overcoming the disease. The adverse effect of Glossina on cattle rearing and their role in the protection of the environment in West Africa is discussed. Meat production possibilities in infested areas, difficulties encountered in tsetse control and related problems are reviewed. Lastly solutions which would assure both livestock development and at the same time protection of the wildlife are examined.

Animal Population Groups↗
PubMed1994

Current research to develop the entomopathogen Bacillus thuringiensis for horn fly control.

Bacillus thuringiensis subspecies israelensis (Bti) has been shown to produce at least two sporulation-specific proteins which result in larvicidal activity when incorporated in bioassays against horn flies (Haematobia irritans L.). Development of a new control technology for horn flies based on Bti appears to be feasible through the use of recombinant DNA technology. Substantial work remains however, to develop new research tools and techniques for this application.

Animals↗
PubMed1994

Pilot scale production and application in wildlife ponds of Lagenidium giganteum (Oomycetes: Lagenidiales).

Lagenidium giganteum, a facultative parasite of mosquito larvae, has recently been registered by the U.S. Environmental Protection Agency for operational mosquito control. We report here the first pilot scale production of the mycelium formulation. Scale-up from 10 to 650 liters was accomplished by a proportionate increase of medium components and volume of water. Foaming of the culture medium had not been encountered previously, but was a serious problem in pilot scale production due to the very rapid growth of a large volume of L. giganteum. Addition of an antifoaming agent did not adversely affect growth, but reduced the ability of the fungus to sporulate. Despite what was effectively a 100-fold reduction in the desired application rate due to reduced sporulation, L. giganteum infected sentinel mosquito larvae and reduced field populations for more than 2 months following application.

Animals↗
PubMed1996

Biotechnology and new integrated pest management approaches.

Area-wide pest management technologies will take on new appearances as the drive to eliminate and/or greatly reduce the use of chemical pesticides increases. The use of genetically altered insects has the most potential for successfully displacing certain pesticides, although the development of genetic engineering technologies for agricultural pest species is still in its infancy. Transformation vectors need to be developed as do transformation methodologies. Here we report the possibility of developing an interspecies vector and discuss ways in which such a vector could be used successfully in an integrated pest management system. If such an approach were developed, it could be utilized with other alternative methods, thereby providing a safe, ecologically sound means of controlling insect pests without damaging the agricultural economy.

Agriculture↗
PubMed1999

Evaluation of transgenic sweet corn hybrids expressing CryIA (b) toxin for resistance to corn earworm and fall armyworm (Lepidoptera: Noctuidae).

Many of the lepidopterous insects which attack sweet corn, Zea mays L., are susceptible to insecticidal proteins produced by Bacillus thuringiensis ssp. kurstaki (Berliner) (Btk). Transgenic sweet corn expressing a synthetic cry gene for production of a Btk-insecticidal protein may provide a more environmentally acceptable means of sweet corn production. Eight transgenic sweet corn hybrids containing a synthetic gene for CryIA(b) protein production (BT11 event) were evaluated for resistance to the corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith). Laboratory tests revealed that all Btk sweet corn hybrids were highly resistant to leaf and silk feeding by neonate 3 and 6 d old corn earworm larvae. Ear damage in the field to the Btk sweet corn hybrids caused by corn earworm was negligible. All Btk sweet corn hybrids, except Btk 95-0901, were moderately resistant to leaf and silk feeding by the fall armyworm. Survival and weight gain were reduced when neonates were fed excised whorl leaves of the Btk plants. Weight gain, but not survival, was reduced when 3- and 6-d-old fall armyworm larvae were fed excised whorl leaves of the Btk plants. Btk sweet corn hybrids appear to be ideal candidates for use in integrated pest management (IPM) programs for both the fresh and processing sweet corn markets, and their use should drastically reduce the quantity of insecticides currently used to control these pests in sweet corn. With appropriate cultural practices, it is highly unlikely that Btk sweet corn will contribute to the development of resistance to Btk proteins in these insects because of the high toxicity of the Cry proteins expressed in these sweet corn hybrids and the harvest of sweet corn ears from fields before larvae can complete development.

Animals↗
PubMed2002

Host races in plant-feeding insects and their importance in sympatric speciation.

The existence of a continuous array of sympatric biotypes - from polymorphisms, through ecological or host races with increasing reproductive isolation, to good species - can provide strong evidence for a continuous route to sympatric speciation via natural selection. Host races in plant-feeding insects, in particular, have often been used as evidence for the probability of sympatric speciation. Here, we provide verifiable criteria to distinguish host races from other biotypes: in brief, host races are genetically differentiated, sympatric populations of parasites that use different hosts and between which there is appreciable gene flow. We recognize host races as kinds of species that regularly exchange genes with other species at a rate of more than ca. 1% per generation, rather than as fundamentally distinct taxa. Host races provide a convenient, although admittedly somewhat arbitrary intermediate stage along the speciation continuum. They are a heuristic device to aid in evaluating the probability of speciation by natural selection, particularly in sympatry. Speciation is thereby envisaged as having two phases: (i) the evolution of host races from within polymorphic, panmictic populations; and (ii) further reduction of gene flow between host races until the diverging populations can become generally accepted as species. We apply this criterion to 21 putative host race systems. Of these, only three are unambiguously classified as host races, but a further eight are strong candidates that merely lack accurate information on rates of hybridization or gene flow. Thus, over one-half of the cases that we review are probably or certainly host races, under our definition. Our review of the data favours the idea of sympatric speciation via host shift for three major reasons: (i) the evolution of assortative mating as a pleiotropic by-product of adaptation to a new host seems likely, even in cases where mating occurs away from the host; (ii) stable genetic differences in half of the cases attest to the power of natural selection to maintain multilocus polymorphisms with substantial linkage disequilibrium, in spite of probable gene flow; and (iii) this linkage disequilibrium should permit additional host adaptation, leading to further reproductive isolation via pleiotropy, and also provides conditions suitable for adaptive evolution of mate choice (reinforcement) to cause still further reductions in gene flow. Current data are too sparse to rule out a cryptic discontinuity in the apparently stable sympatric route from host-associated polymorphism to host-associated species, but such a hiatus seems unlikely on present evidence. Finally, we discuss applications of an understanding of host races in conservation and in managing adaptation by pests to control strategies, including those involving biological control or transgenic parasite-resistant plants.

Animals↗
PubMed1997

Food production and nutrition for the crew during the first 2-year closure of Biosphere 2.

Biosphere 2's finite natural resources: atmosphere, plants, water, and soil, and its unique increased rate of nutrient cycling, mandated a design for the agriculture that emphasized sustainability and high productivity. The results of the initial 2-year test of the agriculture system showed that it could provide a diet that was both nutritionally adequate and pleasing to the palate of the eight-member crew from September 1991 to September 1993. The agriculture design was developed from 1985 to 1991 at the Space Biospheres research greenhouses with consulting from the Institute of Ecotechnics (London) from its experiments in New Mexico, Australia, and France and the Environmental Research Laboratory (University of Arizona). During the 2-year mission this research was continued with the close collaboration of outside scientific consultants, particularly in the area of soil management and integrated pest management. The 2000-m2 cropping area provided approximately 81% of the overall nutritional needs of the crew. Initial results showed light to be the main limiting factor and the additional electric light was added after the first 2-year mission to increase the productivity for future experiments. The diet was primarily vegetarian supplemented with daily amounts of milk, and weekly meals of meat and eggs from the system's domestic goats, pigs, and chickens. Nontoxic methods of pest and disease control were used. The main pest problems were broad mite and root knot nematode. Inedible plant material, domestic animal wastes, and human waste water were successfully processed for nutrient return to the soil. Eighty-six varieties of crops were grown in Biosphere 2. Major staple crops included rice, sweet potato, beets, banana, and papaya. The African pygmy goats were the most productive of the domestic animals producing on average 1.14 kg of milk per day. The diet averaged 2200 calories, 73 g of protein, and 32 g of fat per person per day over the 2 years. The crew had a 10-20% weight loss, mostly occurring in the first 6 months of closure, after which weights stabilized with some increase in the second year. Agriculture field management took 25% of crew time, animal care required an additional 9% and food preparation accounted for 12% of crew labor.

Agriculture↗
PubMed2004

Biological control of sciarid and phorid pests of mushroom with predatory mites from the genus Hypoaspis(Acari: Hypoaspidae) and the entomopathogenic nematode Steinernema feltiae.

In small-scale experiments, the predatory mites, Hypoaspis aculeifer (Canestrini) and H. miles Berlese, applied at 700 mites m(-2), and the entomopathogenic nematode, Steinernema feltiae (Filipjev) applied at 3 x 10(-6) nematodes m(-2) controlled sciarids and phorids in mushroom compost and casing substrates. For both mite species, earliest application to the growing substrate following sciarid infestation reduced sciarid emergence. In contrast, later application of each biological control agent provided more effective control of phorid emergence. The behaviour of adult mites suggested that H. aculeifer were more positively geotactic than H. miles although both species could penetrate compost and casing substrates to a depth of 2-12 cm. A majority of S. feltiae nematodes resided at a depth of 2-4 cm in both substrate types. Independent application of H. aculeifer provided more comprehensive control of sciarids and phorids than the other biological agents studied, owing to its better dispersal within compost and casing, and ability to attack larvae of differing ages.

Agaricales↗