Showing papers on "Infestation published in 1999"
TL;DR: The present study aimed to determine the prevalence of infestation with head lice in children in an urban Australian school.
Abstract: Results Of the 456 children examined, 33.7% (95% confidence interval5 95%-CI 5 [26.9%, 40.4%]) had evidence of infestation with head lice, 21.0% (95%-CI 5 [15.2%, 26.8%]) with active infestation. The prevalence of infestation (active plus inactive) varied greatly between classes, ranging from zero to 72.2% (p , 0.001). Head lice were more prevalent in girls than boys (p , 0.001). Analysis of questionnaires showed that 47.7% (95%-CI 5 [43.0%, 52.4%]) of the children had been infested with head lice in the previous 6 months. For children with active pediculosis capitis on examination, 14.0% (95%-CI 5 [7.9%, 22.4%]) of parents or guardians had not noticed the infestation. Conclusions In an urban primary school in Australia, head lice infestation was present at a hyperendemic level. Clustering by class indicated the classroom as a main source of infestation. Control strategies implemented in schools and including the education of teachers and parents need to be evaluated.
135 citations
TL;DR: This study provides the first evidence for parasite-mediated host natal dispersal and local recruitment in relation to sex and shows that flea infestation led to a higher proportion of male fledglings recruiting in the local population in one year.
Abstract: Dispersal patterns of organisms are a fundamental aspect of their ecology, modifying the genetic and social structure of local populations. Parasites reduce the reproductive success and survival of hosts and thereby exert selection pressure on host life-history traits, possibly affecting host dispersal. Here we test experimentally whether infestation by hen fleas, Ceratophyllus gallinae, affects sex-related recruitment of great tit, Parus major, fledglings. Using sex-specific DNA markers, we show that flea infestation led to a higher proportion of male fledglings recruiting in the local population in one year. In infested broods, the proportion of male recruits increased with brood size over a three year period, whereas the proportion of male recruits from uninfested broods decreased with brood size. Natal dispersal distances of recruits from infested nests were shorter than those from uninfested nests. To our knowledge, this study provides the first evidence for parasite-mediated host natal dispersal and local recruitment in relation to sex. Current theory needs to consider parasites as potentially important factors shaping life-history traits associated with host dispersal.
80 citations
TL;DR: P. decipiens is not a rare but, rather a well-established parasite of the Antarctic fauna, which demonstrates the ability of this cosmopolitan species to complete its life cycle even under conditions of subzero temperatures.
Abstract: The present study provides further data on the occurrence of Pseudoterranova decipiens in fish from two different sampling sites in the Antarctic. A total of 690 fish belonging to 33 species from the eastern Weddell Sea and 322 fish belonging to 12 species from the South Shetland Islands were examined. Altogether, 23 fish species were found to be infested and 11 new host records could be established. P. decipiens occurred at a water depth of between 80 and 820 m. Chaenocephalus aceratus and Notothenia coriiceps from the South Shetland Islands were the species with the highest prevalence (95%) and intensity (2–194 and 1–121, respectively) of infestation. Both are transport hosts, which mainly feed on benthic nototheniid fish species and accumulate the nematodes. Bathypelagic, pelagic, or mainly euphausid feeding fish species were only lightly infested, if at all. This demonstrates the benthic life cycle of P. decipiens in the Antarctic. The preferred site of infestation was the body cavity and the liver; no specimen could be isolated from the fish musculature. This might be explained by the low water temperatures. The infestation of fish from the Weddell Sea was distinctly lower than that of fish around the South Shetland Islands. Besides possible differences in final host populations at the two localities studied, the loss of eggs and larvae under the eastern Weddell Sea shelf ice and over the continental slope and differences in the availability of the first intermediate and macroinvertebrate hosts led to a lower level of infestation. Another role, although nondecisive, may be played by the reduced time of development and infectivity of eggs and larvae, respectively, in the extremely cold waters of the Weddell Sea. P. decipiens is not a rare but, rather a well-established parasite of the Antarctic fauna, which demonstrates the ability of this cosmopolitan species to complete its life cycle even under conditions of subzero temperatures.
75 citations
TL;DR: The wheat midge Sitodiplosis mosellana (Gehin) occurred in all wheat-growing areas of Manitoba during 1993-1997, with 95% of spring wheat fields having some seeds infested by larvae as discussed by the authors.
Abstract: The wheat midge Sitodiplosis mosellana (Gehin) occurred in all wheat-growing areas of Manitoba during 1993–1997, with 95% of spring wheat fields having some seeds infested by larvae. The level of infestation varied, but each year in excess of 20% of seeds were infested in some fields. Infestation levels in adjacent fields were more similar than in fields separated by a few kilometres. Within fields, the infestation was similar at the edge and near the centre. Wheat midge larvae also overwintered in, and adults emerged from, fields in all wheat-growing areas of Manitoba. Adults emerged from the end of June to the end of July most years, and the peak period for adult flight was mid-July, about 1 month later than in parts of Europe where winter wheat predominates. The timing of the emergence was similar from place to place and year to year. Females constituted 95% of insects caught in a flight trap. The first 10% and 50% of the flight occurred on 9 and 16 July, respectively, and the timing of the flight was not related to growing degree-days. In early August, mature larvae began dropping from wheat heads. The timing of infestation of spring wheat was variable among years because of differences in timing between midge flights and the susceptible heading stage of the crop. Nevertheless, the wheat midge flight usually coincided with the susceptible stage of the spring wheat crop.
67 citations
TL;DR: S. alba has good potential as an alternative crop suitable for northern Idaho because it can be grown with reduced late season insecticide application and is completely resistant to cabbage seedpod weevil, and Aphid colonization was observed on plants from all species.
Abstract: The effect of late season insect infestation on seed yield, yield components, oil content and oil quality of two canola species (Brassica napus L. and B. rapa L.) and two mustard species (B. juncea L. and Sinapis alba L.) was examined over 2 years. In each year, ten genotypes from each species were evaluated with late season insects controlled with either methyl parathion or endosulfan insecticides, and without insecticides. Major late season insect damage in 1992 was caused by cabbage seedpod weevil (Ceutorhynchus assimilis Paykull), while diamondback moth (Plutella xylostella L.) and aphids (primarily cabbage aphids, Brevicoryne brassicae L.) were major insect pests in 1993. Insecticide application was very effective in controlling diamondback moth larvae and adult cabbage seedpod weevils, but only partially effective in controlling aphids. Higher numbers of diamondback moth larvae were observed on mustard species compared to canola species. S. alba was completely resistant to cabbage seedpod weevil and there was no damage due to this pest observed. Aphid colonization was observed on plants from all species, but infestation on S. alba and B. rapa occurred too late to have a major effect on seed yield. Seed oil content of canola species was significantly reduced by insect damage although oil quality (indicated by fatty acid profile) was not affected by insect attack. Uncontrolled insect infestation reduced seed yield of canola species by 37 and 32 % in B. napus and B. rapa, respectively. Least yield reduction occurred in S. alba, where average yield reduction from plants in untreated control plots was < 10 % of insecticide treated plants. S. alba, therefore, has good potential as an alternative crop suitable for northern Idaho because it can be grown with reduced late season insecticide application.
62 citations
TL;DR: The results suggest that shell characteristics may be used by processors to identify poor quality nuts and to improve the quality of pistachio nuts sold to consumers.
Abstract: Shell discoloration of pistachio (Pistacia vera) nuts collected from commercial orchards and processing plants was related to fungal decay and insect infestation of the kernel. Nuts with r...
60 citations
TL;DR: There is indeed evidence that birds living in saline habitats have a reduced risk of being parasitized by haematozoa, probably due to a reduced abundance of the invertebrate vectors.
Abstract: A recent hypothesis suggested that migration patterns in waders and other birds could be shaped by the distribution of parasites and diseases. This hypothesis assumes a reduced exposure to parasites in species living in saline habitats. To test this assumption, the number of species of haematozoa and rates of infection reported for bird species living in fresh and salt-water habitats were compared. Species living in more saline habitats had fewer haematozoic parasite species than freshwater birds. Relative frequency of infection was also lower in saltwater species. Neither phylogeny nor the number of individuals examined for blood parasites in each species explained these differences. Thus, there is indeed evidence that birds living in saline habitats have a reduced risk of being parasitized by haematozoa, probably due to a reduced abundance of the invertebrate vectors.
58 citations
01 Jan 1999
TL;DR: Individual calves, exposed to infestation for 14 d on dry-land Kikuyu grass pastures on the coast near Alexandria, were slaughtered at approximately monthly intervals over a period of 2 years and examined for ticks, and although seven species were recovered total tick burdens were for the most part low.
Abstract: HORAK, I.G. 1999. Parasites of domestic and wild animals in South Africa. XXXVII. Ixodid ticks on cattle on Kikuyu grass pastures and in Valley Bushveld in the Eastern Cape Province. Onderstepoort Journal of Veterinary Research, 66:175-184 Individual calves, exposed to infestation for 14 don dry-land Kikuyu grass pastures on the coast near Alexandria, were slaughtered at approximately monthly intervals over a period of 2 years and exam ined for ticks. Although seven species were recovered total tick burdens were for the most part low. Changing the acaricide with which other cattle on the farm, but not the survey calves, were treated from an organophosphate-based compound to a synthetic pyrethroid resulted in a marked sustained reduction in the number of ticks on the calves. Successive pairs of yearling cattle exposed to infestation on a farm in Valley Bushveld were slaugh tered at monthly intervals over a period of 2 years and examined for ixodid ticks. Eleven species were recovered, of which Amblyomma hebraeum, Haemaphysalis silacea, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum were the most abundant and prevalent. Adult A. hebraeum were generally most numerous from early to late summer, adult R. appendiculatus from mid to late sum mer, and adult R. glabroscutatum from spring to mid-summer.
56 citations
TL;DR: The effects of flood and drought on the intensity of infestation of Lemaea cyprinacea in a fish community were analysed during a hydrological cycle in an intermittent stream of the Brazilian semi-arid region.
55 citations
TL;DR: A 2-yr Brachiaria breeding cycle is outlined which incorporates the new spittlebug resistance screening methodology, and refinements in screening methodology increase both reliability and capacity of the screen.
Abstract: Several species and genera of spittlebugs (Homoptera: Cercopidae) are economic pests of grasses in tropical America. They have the potential to cause serious losses on millions of hectares of improved pastures based on cultivars of several species of Brachiaria. Most of the available commercial cultivars of Brachiaria are susceptible to spittlebug. Resistance has been identified in several germplasm accessions and in one of the commercial cultivars, B. brizantha (A. Rich.) Stapf ‘Marandu’. Brachiaria breeding projects require reliable techniques to screen for host plant resistance in large, segregating populations. A series of experiments was conducted to improve evaluation methodology. A smaller plant growth unit, supporting a single-stem, vegetative propagule, was developed and tested. Infestation levels for both adults (6 per plant) and for nymphs (10 per plant) were established. The refinements in screening methodology increase both reliability and capacity of the screen. Infestation of smaller plant propagules saves time, space, and physical resources. It also allows clear expression of insect damage symptoms and hence permits discrimination between tolerance and antibiosis in host plant reaction. Selection can be based on both resistance mechanisms. We outline a 2-yr Brachiaria breeding cycle which incorporates the new spittlebug resistance screening methodology.
54 citations
TL;DR: The impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of Ixodes pacificus ticks infesting the western fence lizard at the University of California Hopland Research and Extension Center (HREC) is examined.
Abstract: We examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of Ixodes pacificus ticks infesting the western fence lizard (Sceloporus occidentalis) at the University of California Hopland Research and Extension Center (HREC), Mendocino County, California. A total of 383 adult lizards were slip-noosed and examined for tick infestation in April and May 1998. At least 94% of the lizards were infested by ticks and at least 20% of the females and 33% of the males carried > 15 ticks. This intensive utilization of western fence lizards (which do not serve as natural reservoirs for Lyme disease spirochetes) by subadult ticks, is probably the primary reason for the low prevalence of infection with Borrelia burgdorferi in I. pacificus nymphs and adults previously recorded at the HREC. Tick loads were higher on male than female lizards. Also, male lizards were generally more heavily infested in late April than in late May. The prevalence of tick infestation exceeded 88% in all habitat types but males collected in woodland and grass/woodland edges had higher tick loads than those collected in open grassland. Male lizards captured in open, exposed grassland tended to carry heavier tick loads in northern/eastern, as compared to southern/western, exposures, and when leaf litter was present.
TL;DR: Persistent fish infestation by the parasitic dinoflagellate Amyloodinium ocellatum was found at a highly saline lake, Salton Sea, California, USA and the seasonal dynamics of the infestation of young tilapia was traced.
Abstract: Persistent fish infestation by the parasitic dinoflagellate Amyloodinium ocellatum was found at a highly saline lake, Salton Sea, California, USA. The seasonal dynamics of the infestation of young tilapia was traced in 1997-1998. First appearing in May, it became maximal in June-August, decreased in October and was not detectable in November. Outbreak of the infestation and subsequent mortality of young fish was registered at the Sea at a water temperature and salinity of 40 degrees C and 46 ppt, respectively. Some aspects of the ultrastructure of parasitic trophonts of A. ocellatum and their location on the fish from different size groups are considered. The interactions of parasitological and environmental factors and their combined effect upon fish from the Salton Sea are discussed.
TL;DR: Phenology of the coffee plant and infestation by coffee berry borer Hypothenemus hampei Ferrari were studied in relation to trapping of adult females in kairomone‐baited traps in a coffee plantation in New Caledonia.
Abstract: Phenology of the coffee plant and infestation by coffee berry borer Hypothenemus hampei Ferrari were studied in relation to trapping of adult females in kairomone-baited traps in a coffee plantation in New Caledonia. In a 0.4 ha coffee field, a group of 27 trees located along a transect beginning at an early infestation point was selected. The number of green, red and dry coffee berries, along with the number of larvae, adult males and females per berry was determined monthly from October 1993 to July 1994. Twelve, red multifunnel traps, each baited with a solution of methanol:ethanol (1:1 ratio, a mean solution release rate of 1 g/day) were placed within the coffee field, along the transect, within the selected trees, grouped in four zones named 1–4. Two additional traps were located outside the plantation.
The proportion of infested berries increased as berry maturity and harvest date approached, while the infestation rate decreased with distance from the epicentre. Over the 10 months of the study, beetle populations increased and spread from the original infestation point across the different zones, according to distance and availability of berries or appropriate physiological status. Traps near the epicentre caught the largest numbers of beetles. Linear relationship between trap catch and infestation level was demonstrated. Traps placed outside the field approached zero catch. Trap catch was highly influenced by rainfall events, and the highest captures coincided with rapidly declining berry numbers on trees. There are good prospects for management of this insect using traps.
TL;DR: A new species of pea crab, Pinnotheres halingi sp.
Abstract: A new species of pea crab, Pinnotheres halingi sp. nov. (Pinnotheridae), found encysted in the right respiratory tree of the sea cucumber, Holothuria scabra (Holothuridea), from Solomon Islands, is described. The reproduction, infestation and pairing behaviour of the crabs were investigated through field observations and experiments. Infestation frequency in 8 monthly samplings of 25–30 holothurians was 98.6±2.6% in Kogu Halingi bay and 0% in two nearby sites. Of 403 pea crabs, 91.4% were found in pairs of opposite sex, 7.9% were single females and <1% were single males. The embryos developed on the female pleopods over ca. 30 days from fertilisation to the release of first zoeae and subsequently went through five pelagic zoeal stages. Infestation occurred at the megalops stage after about 59 days of development. A single pea crab (male or female) per host was found three months after larval infestation. Young males appeared to be strongly attracted to hosts that sheltered a single female, sugges...
TL;DR: Yield reduction and damage ratings were highly correlated under both infestation regimes and the latter trait should be useful for indirect selection to improve European corn borer resistance in maize.
Abstract: The European corn borer, Ostrinia nubilalis (Hubner), is a major pest of maize, Zea mays L., in Central Europe. The resistance of 8 early maturing commercial maize hybrids and 6 experimental hybrids against European corn borer was assessed during 1996 and 1997 in Germany. Resistance was evaluated by yield reduction and damage ratings under natural and manual infestation in 11 or 6 environments, respectively. The infestation level of European corn borer was assessed by the percentage of damaged plants and number of larvae per plant in each environment. Average grain yield of the commercial hybrids was reduced by 0.28% for each 1% of damaged plants and by 6.05% for each European corn borer larvae per plant. All commercial and experimental hybrids were susceptible to European corn borer attack. The commercial hybrids showed little variation in their resistance to European corn borer. The experimental hybrids derived from crosses between resistant inbreds were more resistant than crosses between intermediate and susceptible inbreds. The evaluation of yield reduction required manual infestation because of the low natural infestation level in most environments. However, a comparison of error variances and repeatabilities revealed that they were of similar magnitude for environments with a high level of natural and manual infestation. Yield reduction and damage ratings were highly correlated ( r p ≤ 0.85) under both infestation regimes. Consequently, the latter trait should be useful for indirect selection to improve European corn borer resistance in maize.
TL;DR: Research supported by the Committee for Science and Technology of Spain (project AGF92-0161) and by the Department of Education of the Autonomus Government of Galicia (project XUGA 40301B95).
Abstract: Research supported by the Committee for Science and Technology of Spain (project AGF92-0161) and by the Department of Education of the Autonomus Government of Galicia (project XUGA 40301B95).
TL;DR: The results reinforce the importance of notification in the surveillance of vector species of the invasive type like those currently prevalent in Sao Paulo State.
Abstract: Entomological surveillance of Chagas' disease in Sao Paulo State has adopted a scheme that uses the locality as a unit for field work. Actions are prioritized according to infestation levels obtained by systematic search of triatomine (routine actions), bugs in areas with high infestation levels and in houses whose inhabitants report the presence of the bugs (reply to notification). The most prevalent triatominic species in Sao Paulo State at present are Triatoma sordida and Panstrongylus megistus. A comparative study of infestation levels obtained in houses and surroundings in routine search and replies to notification in the two-year periods of 90/91, 92/93 and 94/95, has shown average percentage positivity of 1.3 indoors in routine activity and 6.2 in the reply to notification. For the house surroundings the values were 8.6 and 18.2 respectively, no differences being found between the two-year periods. Replies to notification showed average percentage positivity (focus) in 26% of the houses. It was verified that the notifications had come from localities with prior infestation levels equal to zero (I = O), intermediary infestation levels (I 5), although the percentages of positive replies to notification were higher in those localities with high prior infestation levels. These results reinforce the importance of notification in the surveillance of vector species of the invasive type like those currently prevalent in Sao Paulo State.
TL;DR: The results showed that the data from all investigated cropping areas fit well to an exponential model with two parameters, the length and width gradient parameters, which follow a normal distribution, and significant differences in these parameter values between cropping area could not be demonstrated.
Abstract: Infestation foci of potato cyst nematodes (Globodera rostochiensis and G. pallida) in the provinces of Zeeland, Friesland, Groningen, and Drente of the Netherlands were sampled to validate a model describing infestation foci based on data from Flevoland. Eighty-two fields were presampled to locate infestation foci using a coarse sampling grid (8 × 3 m). Parts of 37 fields containing one or more foci were sampled intensively by extracting at least 1.5 kg of soil per square meter (1.33 × 0.75 m). Forty foci were analyzed for spatial distribution characteristics of cysts using multiple regression with generalized linear models and classical linear models. The results showed that the data from all investigated cropping areas fit well to an exponential model with two parameters, the length and width gradient parameters. Significant differences in these parameter values between cropping areas could not be demonstrated. As both parameters follow a normal distribution, the probability of any combination ...
TL;DR: The finding of crabs without bopyrids, but with distended branchial chambers, shows that some crabs survive the infestation of Paralomis granulosa, and suggests that the reproductive potential of the crab population is not seriously affected by the sterilizing effect of the parasite.
Abstract: A total of 16,692 specimens of Paralomis granulosa was collected in the Beagle Channel, Tierra del Fuego, Argentina, between July 1996 and July 1997. This lithodid was parasitized by a bopyrid isopod identified as Pseudione tuberculata. Infested crabs exhibited a conspicuous bulge on their carapaces, which accommodated the parasite housed in the branchial chamber. The prevalence of infestation by P. tuberculata decreased with crab size, from 45.6% at 10―19.9-mm to 0% at 90―99.9-mm carapace length. Bopyrids were found on 251 occasions in the left branchial chamber and only once in the right branchial chamber. Except for two immature female parasites found in the branchial chamber of a small crab, all parasites were mature females, each usually carrying a dwarf male attached to its abdomen. The length of the female isopods and that of their hosts were positively correlated. These two observations suggest that the parasites infest P. granulosa early in the life of the host, and remain on. and grow up with the host throughout its life. The finding of crabs without bopyrids, but with distended branchial chambers, shows that some crabs survive the infestation. While breeding is inhibited in parasitized hosts, the prevalence of the parasite is already low (about 1.2%) at the size of host maturity. Therefore, we suggest that the reproductive potential of the crab population is not seriously affected by the sterilizing effect of the parasite. Finally, the cooccurrence of this bopyrid and a second parasite, the rhizocephalan Briarosaccus callosus, was recorded, but the prevalence of double infestations was low.
TL;DR: During the summer months when Falkland mussels are in peak reproductive condition, dry flesh weight of infested mussels was significantly lower than noninfected mussels of comparable size suggesting that infestation by C. parasitica may reduce reproductive output.
Abstract: The association between the green alga Coccomyxa parasitica (Chlorococcales) and the mussel Mytilus edulis chilensis at Goose Green, Falkland Islands is reported. C. parasitica occurred within the soft tissues with an overall infestation rate of 16%. The highest levels of infestation (23%) occurred in individuals from the middle of the main mussel bed, with considerably lower levels of infestation in the upper and lower regions (,1% and 5% respectively). No consistent seasonal pattern in infestation rate was detected between September 1993 and February 1996. C. parasitica was most commonly observed in tissues located in the posterior territory of the host, in areas most directly exposed to light. Tissues of infested mussels were rather watery and translucent and the adductor muscle appeared weak and stringy. During the summer months when Falkland mussels are in peak reproductive condition, dry flesh weight of infested mussels was significantly lower than noninfected mussels of comparable size suggesting that infestation by C. parasitica may reduce reproductive output. However it is uncertain whether poor condition of the host is due to the presence of the parasitic alga or whether C. parasitica infests only those mussels that are already in poor condition.
TL;DR: It is reported for the first time 28 bird species as hosts of the immature stages of A. cajennense, demonstrating the lack of host specificity of the larvae and nymphs.
Abstract: We evaluated the prevalence, mean intensity and relative density of ticks in 467 wild birds of 67 species (12 families) from forest and cerrado habitats at two protected areas of Minas Gerais, between March and September 1997. Ticks collected (n=177) were identified as larvae and nymphs of Amblyomma cajennense and four other species of Amblyomma. We report for the first time 28 bird species as hosts of the immature stages of A. cajennense, demonstrating the lack of host specificity of the larvae and nymphs. A. cajennense had 15% prevalence on birds, with a mean infestation intensity of 0.37 ticks per host sampled, and 2.5 ticks per infested bird. Prevalence varied in relation to host species, diet and between birds from forests at two successional stages. There were no differences in relation to host forest dependence, participation in mixed flocks of birds, and nest type constructed. A. cajennense is a species of medical and veterinary importance, occurring on domestic animals but is known little of its occurrence on wildlife.
TL;DR: Natural mortality of gypsy moth eggs, larvae, and pupae was examined at several locations along a gradient of infestation in Ontario, Canada and the mycopathogen Entomophaga maimaiga Humber, Shimazu & Soper was found.
Abstract: Natural mortality of gypsy moth [Lymantria dispar (L.) (Lepidoptera: Lymantriidae)] eggs, larvae, and pupae was examined at several locations along a gradient of infestation in Ontario, Canada. Most mortality of eggs was the result of exposure to winter weather. This mortality was mitigated in egg masses located near ground level where they benefited from snow cover. At least six species of parasitoids were found attacking gypsy moth larvae and pupae. The most common species were present in the same rank order of abundance at all sites. Identified pathogens were also present in most sites but their relative abundance varied greatly. The mycopathogen Entomophaga maimaiga Humber, Shimazu & Soper (Zygomycetes: Entomophthorales) was found at all sites and usually was responsible for the highest levels of observed, single-source mortality at the site.
TL;DR: The percentage infestation by this parasite was found to be significantly lower in adult Africanized bees than Italian bees, and mean mite infestation in Brazil on both kinds of bees was only about a third of that found in Mexico.
Abstract: Different levels of infestation with the mite Varroa jacobsoni have been observed in the various Apis mellifera races. In general, bees of European races are more susceptible to the mite than African honey bees and their hybrids. In Brazil honey bee colonies are not treated against the mite, though apparently both climate and bee race influence the mite infestation. Six mixed colonies were made with Italian and Africanized honey bees. The percentage infestation by this parasite was found to be significantly lower in adult Africanized (1.69 ± 0.44) than Italian bees (2.79 ± 0.65). This ratio was similar to that found in Mexico, even though the Africanized bees tested there had not been in contact with varroa, compared to more than 20 years of the coexistence in Brazil. However, mean mite infestation in Brazil on both kinds of bees was only about a third of that found in Mexico.
Journal Article•
Journal Article•
TL;DR: In this paper, the acaricide with which other cattle on the farm, but not the survey calves, were treated from an organophosphate-based compound to a synthetic pyrethroid resulted in a marked sustained reduction in the number of ticks on the calves.
Abstract: Individual calves, exposed to infestation for 14 d on dry-land Kikuyu grass pastures on the coast near Alexandria, were slaughtered at approximately monthly intervals over a period of 2 years and examined for ticks. Although seven species were recovered total tick burdens were for the most part low. Changing the acaricide with which other cattle on the farm, but not the survey calves, were treated from an organophosphate-based compound to a synthetic pyrethroid resulted in a marked sustained reduction in the number of ticks on the calves. Successive pairs of yearling cattle exposed to infestation on a farm in Valley Bushveld were slaughtered at monthly intervals over a period of 2 years and examined for ixodid ticks. Eleven species were recovered, of which Amblyomma hebraeum, Haemaphysalis silacea, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum were the most abundant and prevalent. Adult A. hebraeum were generally most numerous from early to late summer, adult R. appendiculatus from mid to late summer, and adult R. glabroscutatum from spring to mid-summer.
TL;DR: The model simulations do not support the concept of a 'lag' phase as distinct from the 'growth' phase in the changing pattern of mite abundance on an infested sheep and suggests that the observed pattern of growth is a natural function of an exponential increase in numbers.
TL;DR: At most times of the year inspections for sheep lice should be concentrated on the sides and back, but in recently shorn sheep greater attention should be paid to the lower neck and ventral regions, and implications of the observed distributions for the efficacy of chemical treatments are discussed.
Journal Article•
TL;DR: In this article An.
Abstract: In this article An. melas infestation rate for P. falciparum is compared to the rate of An. gambiae in the coastal and lagoon area of Benin where the two species are sympatric. We studied the variation of An. gambiae complex infestation rate in three zones where the two species occur in different proportions. This infestation rate is higher in areas where An. gambiae is prevalent. In a second experiment we separated An. melas and An. gambiae according to cytogenetic and biometrical analysis. Then we established the infestation rate of each species by microscope examination of salivary glands and presence of P. falciparun C.S. antigens by ELISA method. In areas where An. melas is the most abundant species (80-90%), the sporozoitic index and antigen C.S. + P. falciparum rate are significantly lower. These results are confirmed by the infestation rates observed for each species. In conclusion, An. melas infestation rate is significantly lower than the An. gambiae one. An. gambiae is the best malaria vector in Africa. In spite of an environment such as Ganvie where animals are rare, which increases anthropophilic and endophilic tendencies of An. melas, antigens CS P. falciparum rate of An. gambiae (3.5%) are significantly higher than An. melas (1.9%).
TL;DR: A correlation was found between the number of females caught per trap and either the percentage of damaged ears or the damage index, indicating that the simultaneous counting of males and females in cone traps can be an efficient and simple monitoring tool.
Abstract: Infestation with Ostrinia nubilalis (Hb.), the European corn borer (ECB) can be detected by using different sampling techniques in the field and statistical models aimed to assess the development time of ECB larvae and crop damage. An appropriate monitoring for this polyphagous species to show a relationship between the kind of sampling or a model and the subsequent damage in a particular crop, is very difficult. Sex pheromone traps, generally, are also not reliable for monitoring ECB. The possibility of employing new types of traps baited with a sex pheromone and a maize kairomone, the phenylacetaldheyde (PAA) (multibaited traps) was investigated. In sweet corn, trapping experiments were conducted over a 2-year period with two kinds of cone traps (XLa and XLb) set up at the borders of fields (four replicates). ECB attacks of first and second generation larvae were evaluated in the corn ears as a percentage of damage and using a damage index (DI). A correlation was found between the number of females caught per trap and either the percentage of damaged ears (r = 0.73 for XLa; r = 0.65 for XLb) and the DI (r = 70 for XLa; r = 0.60 for XLb). Conversely, the number of males caught per trap was not correlated with ECB larval damage. A linear model of multiple correlation fitted to the data of simultaneous captures of males and females showed that the coefficients were not higher than simple correlation. The correlation coefficients obtained by fitting a curvilinear response surface were higher (r = 0.81 for XLa and r = 0.84 for XLb, respectively, related to percentage of damaged ears; r = 0.79 for XLa and r = 0.76 for XLb, respectively, related to DI) thus indicating that the simultaneous counting of males and females in cone traps can be an efficient and simple monitoring tool.