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[Experimental study of larval efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (fish-Poecilidae)].

Experimental study of efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (Fish-Poecilidae). Gambusia affinis is a culiciphage fish which was introduced in Tunisia in 1929 to control mosquito larvae. In the present study, we confirm, under laboratory conditions, the good efficacy of Gambusia affinis against mosquito larvae. The consumption of larvae decreases with the evolution of larvae instars and increases, for the same instar, in relation with the fish size. In fact, the size of the prey is related to the predator's size: fish belonging to the length class [20-24 mm] prefer IIIrd instar, fish from class length [25-29 mm] prefer pupae and IVth instar. The trophic test shows that G. affinis has a clear preference for Culicidae larvae, except fish belonging to the 2 length classes [35-39 mm] and [40-44 mm] for which Culicidae and Ephemeroptera have similar preference. In addition, at high temperature (30 degrees C), Gambusia affinis has a higher efficiency.

Animals↗

[Acute lethal and behavioral response of Liposcelis bostrychophila (Psocoptera: Liposcelididae) to DDVP].

Book louse Liposcelis bostrychophila is a minor pest in stored products, and may seriously infest the stored products when its population outbreaks. This study was conducted to evaluate the toxic effect of DDVP on various development stages of L. bostrychophila. The results showed that at 28 +/- 0.5 degrees C and 24 h exposure under 75%-80% RH, the LC50 of the eggs, larvae of 1st to 4th stadium, and adults was 16.83, 0.22, 0.22, 0.23, 0.26 and 0.25 micrograms.L-1, respectively. The lethal effect of DDVP on the adults at different exposure periods showed that their mortality was linearly related to the treated time, implying that the test colony of L. bostrychophila was susceptible to DDVP. In the practical fumigation, DDVP as a fumigant had a good effect on the pest control if the development stage, time and periods of treatment were appropriate.

Animals↗

[Suppressive effect of plant secondary substances and ecological measures on Liriomyza sativae population].

A state-space population model was used to evaluate the effect of plant secondary substances and ecological measures on the population dynamics of the vegetable leafminer, Liriomyza sativae. In the vegetable field, by spraying alcohol extracts of Lantana camara (1 g.100 ml-1), or spraying the petroleum spray oil (300 x), or releasing the parasitoids, the indices of population control(IIPC) of L. sativae compared with control were 0.136, 0.222 and 0.292, respectively, but the index of population trend of vegetable leafminer in control was as high as 11.15, the population of vegetable leafminer still increased by control each one of the methods. Based on the state space analysis, the controlling effects of the alcohol extracts combining with other methods on vegetable leafminer were stimulated, which showed that the alcohol extracts from Lantana camara (1 g.100 ml-1) plus horticultural spray oils(300 x) used once at the period of adult summit, and the parasitoids released 1000 to 2000 per 100 m2 gave the index of population of vegetable leafminer below 1, means that vegetable leafminer would be controlled sustainably.

Animals↗

[Effectiveness of Eretmocerus sp. and Aschersonia aleyrodis in controlling Bemsia tabaci populations].

The effectiveness of Eretmocerus sp. and Aschersonia aleyrodis in controlling Bemisia tabaci populations on cucumber were determined in separated and combined greenhouse experiments. The results showed that after spraying A. aleyrodis (5 x 10(6) spores per ml, twice per generation) and releasing Eretmocerus sp. (3 female per plant, twice per generation), 95.74% and 57.58% of whitefly populations were controlled, respectively. However, when the two natural enemies were used together with the same rate mentioned above (A. aleyrodis spraying twice followed by releasing Eretmocerus sp. once or twice in one generation), 97.02%-97.91% of whitefly populations were controlled. Moreover, the increasing index of whitefly population (I) subjected to both natural enemies together was below I, indicating the substantial reduction in whitefly population. The combined treatments provided a better control effect of whitefly than separated ones, and there was no contradicted effect between both natural enemies.

Animals↗

Procedures for the evaluation of field efficacy of slow-release formulations of larvicides against Aedes aegypti in water-storage containers.

In Thailand, water-storage jars, barrels, drums, pails, and tanks constitute vast developmental sites for Aedes aegypti in urban, semiurban, and rural areas. Earthen water jars, cement jars, and concrete tanks constitute the greatest proportion of artificial containers where Ae. aegypti breed. This species is a major vector of the causal agents of dengue and dengue hemorrhagic fever, and vector control by larviciding is one of the main approaches to disease control. At present, temephos sand granules (SG) (1%) are used in large-scale community-based larviciding programs. Because of the use of this larvicide over the past 30 years, the likelihood exists that Ae. aegypti already has become resistant to this larvicide. To develop more options for control and make them available for use, we evaluated VectoBac tablets (Bacillus thuringiensis var. israelensis [Bti] 5%) and a new formulation of zeolite granules (ZG) of temephos (1%) and compared these formulations for efficacy with temephos SG (1%) in water-storage jars. In these tests, we used 48 identical glazed earthen water-storage jars (200-liter capacity) and developed quantitative sampling procedures for larvae, pupae, and pupal skins. Pupal skins were the easiest to count and this technique was used for the 1st time for assessing emergence of adults in water-storage containers. Three water regimens were used: full jars, half-full jars, and full jars emptied half way and refilled weekly. The 3 formulations with 3 regimens of water were assessed over a period of 6 months. VectoBac tablets at the dosage of 1 tablet or 0.37 g per 50 liters of water provided excellent control for about 112 days in full water jars. In the other 2 water regimens, VectoBac gave excellent control for 90 days. The 2 temephos formulations at the operational rate of 5 g per 50 liters of water were equal in efficacy, yielding almost 100% control for more than 6 months. Unlike temephos SG, the temephos ZG had no objectionable odor. Both the temephos ZG and Bti tablets increased clarity of the water, a feature desired by the users. Lack of odor and depression of turbidity are important attributes of Bti tablets and temephos ZG.

Animals↗

[Environmental hygiene tasks of the veterinarian in practice].

Apart from his direct tasks like treating diseased animals, preservation of animal health, recognition of mal-feeding and failures, recognition of unsuitable keeping systems and acknowledgement of animal welfare the veterinary practitioner can be the environmental-hygienic consultant of the farmer in following areas in particular: management and technique of feeding; management and technique of water supply; management and technique of air quality and ventilation; management and technique of manure handling and hygiene; cleaning and disinfection; deratting and pest control. The aim of these tasks is to diminish the risks/hazards for food products (food control act), the air (emission control act), surface water (law on the water household), ground water (waste control act, law on the water household) and vegetation and soil (waste control act, nature conservation act). Some examples will be given and comments are made on how to run a practice in an environmentally friendly way.

Air Pollution, Indoor↗

Effect of ten chlorophytes on larval survival, development and adult body size of the mosquito Aedes aegypti.

The effect of ten microalgal chlorophytes isolated from mosquito breeding containers on the survival, larval development and adult body size of the mosquito Aedes aegypti was investigated. All larvae fed with six of the microalgal isolates died after 7 days. These isolates were found to be resistant to digestion by mosquito larvae. Delayed pupation and body size reduction of the mosquitos fed with Chlorococcum UMACC 218 and Scenedesmus UMACC 220 were observed. In contrast, larvae fed with Ankistrodesmus convolutus UMACC 101 and Chlorococcum UMACC 213 were bigger in size than those fed with normal insectory feed. The present study showed that microalgal chlorophytes have the potential to be used as larvicidal agents for mosquitos.

Aedes↗

Acute pesticide poisoning related deaths in Turkey.

This study determined the spectrum of deaths due to acute agrochemical poisoning in Turkey. Data was obtained from all autopsy reports performed between 1997 and 2001, compiled by the Institute of Forensic Medicine (which is a department of the Ministry of Justice), and evaluated retrospectively. There were 3990 deaths by intoxication of one form or another. Acute agrochemical/pesticide poisoning caused 843 deaths. Almost half were under 30 yo; 55% were female and 45% were male. Of 205 deaths whose manner of death was determined, 153 (75%) were suicide; the most common substance used was insecticide followed by sulfur, rodenticides, and herbicides. The pattern appeared consistent from 1997 to 2001 with no decline in the number of cases, despite the government having taken measures to educate the public and reduce pesticide use by offering alternates to control pests and insects.

Adolescent↗

[Control of chironomids in water by immobilized Bacillus thuringiensis var. israelensis de Barjac].

A strain from Bacillus thuringiensis var. israelensis de Barjac (B. t. i), having a fatal toxicity to chironomids, was immobilized in the PVA-H3BO3 gel beads confected with a bit of sodium alginate and activated carbon. The result showed that optimal weight ratios were 10% PVA, 1% sodium alginate and 20% activated carbon, respectively. When 4% calcium chloride saturated boric acid solution (pH=6.7) was used as gelatin agent for gelating 24 h, the produced gel beads had good performance in mechanical strength. This method is proved to be simple and cheap. The toxicity of the beads to chironomids is high and the release is slow.

Animals↗

[Environmental pollution--assessment of environmental medicine questionnaires and data in Schleswig-Holstein from 1995-1997].

Physicians qualified in environmental medicine due to their participation in special training courses in the federal state Schleswig-Holstein (Germany) may use a standardized questionnaire to report on their environmental medicine-related cases. The course of the illness and recovery, respectively, if known, is to be documented on a separate data sheet. During a three year period from 1995 to 1997 716 cases and 216 courses of illness and recovery, respectively, have been reported. The relevant environmental factors/toxicants of exposure most frequently documented by these physicians and found to be related to symptoms of illness were biocides (mainly insecticides used indoors for pest control, 31%) molds (30%), dental amalgam (28%), solvents or volatile organic compounds (VOC, 23%) and formaldehyde (17%), respectively. In 47% of the documented cases an exposure to more than one environmental factor/toxicant was registered. Age distribution as well as the symptoms of illness of the patients were found to be dependent on the type of exposure. After the physicians diagnosis of an environmental medicine-related illness the exposure was stopped completely in 57% of those cases of whom the course of the illness was known. Recovery was reported in 62% of these patients, and additional 30% had improved but had not recovered completely at the time of data-assessment. From these results it may be concluded that research work in the field of environmental medicine should be enforced in order to prevent unnecessary illness and to lower the costs of the public health system.

Adolescent↗

Combination of Mesocyclops thermocyclopoides and Bacillus thuringiensis var. israelensis: a better approach for the control of Aedes aegypti larvae in water containers.

The efficacy of a local Thai-strain of the copepod, Mesocyclops thermocyclopoides and the larvicide, Bacillus thuringiensis var. israelensis (Bti), used jointly and singly, was studied against Aedes aegypti in water containers. In a laboratory test, copepods alone produced mortality of 98-100% in 1st instar larvae of Ae. aegypti at copepod:larvae ratios ranging from 1:1 to 1:4. In an outdoor field simulated experiment that ran for 16 wk, after a single inoculation, the treatment of copepods and Bti combined yielded the better, more sustainable results than the agents used individually. Numbers of mosquito larvae per sample in the combined treatment were zero during the first 8 wk; larval numbers then increased but were maintained at a very low level for the next 4 wk after which the larval numbers increased moderately but still remained below numbers in the control. Bti alone kept the larvae at the zero level for the first 4 wk after which their numbers increased slightly and were at low levels up to 12 wk. Copepods alone maintained larval numbers at a low level as compared with those of the control. During the course of the experiment the larval numbers in the control were greater than 20 per sample. Statistically significant differences were noted among treatment means (F = 23.083, df = 3/60, P<0.01) over the total period of the study. The number of copepods in the joint treatment was significantly higher than in the copepod alone treatment for the first 8 wk (t = -4.97, df = 14, P<0.01). The density of copepods, however, for the whole 16-wk period was not significantly different in these two treatments (t = -1.51, df = 30, P>0.1).

Aedes↗

Potential of crude seed extract of celery, Apium graveolens L., against the mosquito Aedes aegypti (L.) (Diptera: Culicidae).

Crude seed extract of celery, Apium graveolens, was investigated for anti-mosquito potential, including larvicidal, adulticidal, and repellent activities against Aedes aegypti, the vector of dengue haemorrhagic fever. The ethanol-extracted A. graveolens possessed larvicidal activity against fourth instar larvae of Ae. aegypti with LD50 and LD95 values of 81.0 and 176.8 mg/L, respectively. The abnormal movement observed in treated larvae indicated that the toxic effect of A. graveolens extract was probably on the nervous system. In testing for adulticidal activity, this plant extract exhibited a slightly adulticidal potency with LD50 and LD95 values of 6.6 and 66.4 mg/cm2, respectively. It showed repellency against Ae. aegypti adult females with ED50 and ED95 values of 2.03 and 28.12 mg/cm2, respectively. It also provided biting protection time of 3 h when applied at a concentration of 25 g%. Topical application of the ethanol-extracted A. graveolens did not induce dermal irritation. No adverse effects on the skin or other parts of the body of human volunteers were observed during 3 mo of the study period or in the following 3 mo, after which time observations ceased. A. graveolens, therefore, can be considered as a probable source of some biologically active compounds used in the development of mosquito control agents, particularly repellent products.

Aedes↗

[Work-relatedness of asthma among outpatients].

The American Thoracic Society (ATS) issued a statement in 2002 that approximately 15% of adult asthma was likely to be work related and emphasized the importance of prevention for occupational asthma. However, the occupational contribution of the burden of asthma has been not understood, because there are very few epidemiological studies in the general population in Japan that examined the population attributable risk (PAR) of asthma due to occupational exposures. Assessing this component of the burden of asthma can better inform preventive strategies. Therefore, we examined the PAR of adult asthma due to occupational exposures among outpatients by using the National Institute for Occupational Safery and Health (NIOSH) criteria. Additionally we examined characteristics of cases of work-related asthma. The results indicate that the PAR of asthma due to occupational exposures is 22.7%, a value comparable to previous reports in Western countries. Therefore, we thought that it suggested that the prevalence of work-related asthma in Japan is similar to Western countries. Five patients met the criteria for having "probable OA", and their occupations were pest control industry, florist, hairdresser and pet groomer. Two patients (40%) changed their jobs due to asthma, which suggests that work-related asthma materially affects continuation of employment. Four patients (80%) had asthma despite leaving their jobs, which suggests that it is crucial to prevent work-related asthma.

Adult↗

Elimination of dengue by community programs using Mesocyclops(Copepoda) against Aedes aegypti in central Vietnam.

From September 2000 to June 2003, a community-based program for dengue control using local predacious copepods of the genus Mesocyclops was conducted in three rural communes in the central Vietnam provinces of Quang Nam, Quang Ngai, and Khanh Hoa. Post-project, three subsequent entomologic surveys were conducted until March 2004. The number of households and residents in the communes were 5,913 and 27,167, respectively, and dengue notification rates for these communes from 1996 were as high as 2,418.5 per 100,000 persons. Following knowledge, attitude, and practice evaluations, surveys of water storage containers indicated that Mesocyclops spp. already occurred in 3-17% and that large tanks up to 2,000 liters, 130-300-liter jars, wells, and some 220-liter metal drums were the most productive habitats for Aedes aegypti. With technical support, the programs were driven by communal management committees, health collaborators, schoolteachers, and pupils. From quantitative estimates of the standing crop of third and fourth instars from 100 households, Ae. aegypti were reduced by approximately 90% by year 1, 92.3-98.6% by year 2, and Ae. aegypti immature forms had been eliminated from two of three communes by June 2003. Similarly, from resting adult collections from 100 households, densities were reduced to 0-1 per commune. By March 2004, two communes with no larvae had small numbers but the third was negative; one adult was collected in each of two communes while one became negative. Absolute estimates of third and fourth instars at the three intervention communes and one left untreated had significant correlations (P = 0.009-< 0.001) with numbers of adults aspirated from inside houses on each of 15 survey periods. By year 1, the incidence of dengue disease in the treated communes was reduced by 76.7% compared with non-intervention communes within the same districts, and no dengue was evident in 2002 and 2003, compared with 112.8 and 14.4 cases per 100,000 at district level. Since we had similar success in northern Vietnam from 1998 to 2000, this study demonstrates that this control model is broadly acceptable and achievable at community level but vigilance is required post-project to prevent reinfestation.

Aedes↗

Study of larvivorous fish for malaria vector control in Somalia, 2002.

An intervention study was conducted on the introduction of the larvivorous fish Oreochromis spilurus spilurus as a method of malaria vector control in Kalabeydh village, northern Somalia. This species is resistant to chlorine in water up to a concentration of 1.0 mg/L. Fish were introduced into 25 berkit (reservoirs). After 1 month the number of larvae in each berkit was reduced by between 16.5% and 78.6% (mean 52.8%). Community acceptance and participation was good. The introduction of larvivorous fish is a cheap method of malaria vector control, but its sustainability needs special consideration and education of the community is important, especially to cover the dry season, when most of the berkit dry up.

Animals↗

Genotoxic effects of pentachlorophenol, lindane, transfluthrin, cyfluthrin, and natural pyrethrum on human mucosal cells of the inferior and middle nasal conchae.

BACKGROUND: Animal experiments and epidemiological studies suggest that pentachlorophenol (PCP) and gamma-hexachlorocyclohexane (lindane) should be classified as possible human carcinogens. In the past, both have had a variety of applications in the civilian and military sectors and in forestry. They have, e.g., been used to impregnate and treat uniforms and other fabrics and to control human lice. Animal experiments indicate that PCP in particular causes mutations and chromosome aberrations and thus DNA damage. Studies on whether or not this also applies to newer substances and especially to natural type I and type II pyrethroids still are not available. What is particularly lacking are data on the genotoxic effects of these substances on human target cells. Our study describes the genotoxic effects of PCP, lindane, transfluthrin, cyfluthrin, and natural pyrethrum on human mucosal cells of the inferior and middle nasal conchae. METHODS: Epithelial cells were isolated from nasal mucosa, which was removed in the surgical treatment of chronic sinusitis and nasal concha hyperplasia. After the cells had been tested for vitality using the trypan blue exclusion test, the short-term culture method was used. The material was incubated with PCP (0.3, 0.75, and 1.2 mmol), lindane (0.5, 0.75, and 1.0 mmol), transfluthrin (0.05, 0.1, 0.5, 0.75, and 1.0 mmol), cyfluthrin (0.05, 0.1, 0.5, 0.75, and 1.0 mmol), natural pyrethrum (0.001, 0.005, 0.01, 0.05, and 0.1 mmol), and N-methyl-N'-nitro-N-nitrosoguanidine for 60 minutes. Substance-induced DNA damage (single-strand and double-strand breaks) were determined using single-cell microgel electrophoresis. A fluorescence microscope was used together with an image processing system to analyze the results obtained. RESULTS: After exposure to all tested substances, a high percentage of the cells of the middle nasal concha in particular were found to have severely fragmented DNA as a result of strong genotoxic effects. Although the reaction of the cells of the inferior nasal concha was significantly less strong (p < 0.001), the tested substances were nevertheless found to have a notable genotoxic effect on these cells too. CONCLUSION: Our study strongly suggests that exposure to PCP, lindane, transfluthrin, cyfluthrin, and natural pyrethrum has a genotoxic effect on the epithelial cells of human nasal mucosa. In addition, we have shown that nasal structures differ in susceptibility to the various pesticides used in the tests. Thus, the study provides new evidence supporting the biological plausibility of PCP- and lindane-induced effects, thereby helping evaluate potential PCP- and lindane-induced mucous membrane carcinomas of these parts of the nose. In addition, our study shows that other substances that today are widely used for controlling pests have a considerable genotoxic effect on human target cells. The results obtained indicate the need for additional studies on the genotoxicity of these substances and their adverse effects on human health.

Adolescent↗

[Field attraction effects of different trapping methods on Monochamus alternatus].

A comparative study on the field attraction effects of different attractant, trap, lure and controlled-releasing amount on Monochamus alternatus showed that four test attractants had a certain trapping ability to Monochamus alternatus, among which, MA2K05 was the strongest, with a mean capture efficiency of 26.3 individuals each trap and being attractive to other species of Loleoptera and Hemiptera; MA2K13 took the second place, with 21.3 individuals each trap; while MA2K11 was the weakest, with 13.8 individuals each trap. Among the three lures tested, lures C (60 ml plastic cup with 2 of 5 cm round holes on the cover) and B (20 ml specified controlled-releasing plastic bottle) had a comparatively stronger effect, with a capture efficiency of 34.25 and 20.3 individuals each trap, respectively; while lure A (20 ml specified controlled-releasing plastic bottle, the releasing amount being smaller than that of lure B) was the weakest, with 14.7 individuals each trap. Because the attractant volume of lure C was 1.5 times larger than that of lures B and A, and the attractant for lure C was appended every 3-5 d, while that for lures B and A could be used for more than a month with once appended, lure B was the best on the whole. As for the test traps, Xuanzhou trap was superior to imitated Japanese trap, with a trapping efficiency of 36.4 and 9.7 individuals each trap, respectively. The attractiveness of attractants was not significantly enhanced when the dosage was increased from 20 ml to 80 ml, but significantly improved when it was up to 120 ml.

Animals↗