Infestation

About: Infestation is a research topic. Over the lifetime, 8308 publications have been published within this topic receiving 82305 citations.

Reduction of European Corn Borer (Lepidoptera: Pyralidae) Damage by Intercropping Corn with Soybean

Abstract: Corn, Zea mays L., and soybean, Glycine max (L.) Merrill, were intercropped for silage in 1985 and 1986 at the Central Experimental Farm, Ottawa, to determine effects on yields and the percentage of European corn borer, Ostrinia nubilalis Hubner, infestation. A 2 × 2 × 3 factorial was analyzed with two corn hybrids (dwarf PAG 391134 and tall Coop 5259), two corn cropping systems (monocropped and intercropped), and three nitrogen fertilizer levels (0, 60, and 120 kg N/ha). Intercropping significantly reduced European corn borer infestation in tall corn in 1985 and in both corn hybrids in 1986. Dwarf corn was infested significantly less than tall corn in both years and in both cropping systems. The commonly applied rate of 120 kg N/ha resulted in the highest European corn borer infestation. Yields and land equivalent ratios at 60 kg N/ha were as high as those at 120 kg N/ha, but European corn borer infestation was significantly less at 60 kg N/ha. Application of 0 kg N/ha resulted in the lowest yields and land equivalent ratios, but European corn borer infestation was not different from levels at 60 kg N/ha.

Midwest farmers' perceptions of crop pest infestation

Abstract: Region, soil type, and tillage are important factors in severity of crop pest infestation. This study was conducted to determine the relative importance of these factors on severity of crop pest infestation as perceived by farmers. Correlations between pests were also studied. In a 1992 survey, farmers in 12 U.S. Corn Belt states were asked to rate the severity of crop pest infestation in their fields. The categories of pests included perennial and annual weeds in row crops, insects and diseases of corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench], and insects and diseases of soybean [Glycine max (L.) Merr.]. Means ranked from highest to lowest in the following order: annual weeds, perennial weeds, corn and sorghum insects, corn and sorghum diseases, soybean diseases, and soybean insects. Correlation coefficients ranged between 0.47 to 0.69 among corn and sorghum diseases, among soybean insects, and among soybean diseases, and between 0.04 and 0.41 among perennial weeds. Correlation coeffidents among annual weeds and among corn and/or sorghum insects spanned both of these ranges. Effects of either region and/or tillage were very highly significant (0.001), while soil type was not as significant an effect. In farmers' perceptions, weeds were the most serious pests and soybean pests the least serious pests; there was less relationship among perennial weeds than among pests in any other category; the drier western region was generally less severely infested; higher amount of conventional tillage practices produced less infestation; and differences in soil type were due to more severe infestation in loams, followed by infestation in clays, and then infestation in sands.

Head lice prevalence and associated factors in two boarding schools in Sivas.

Abstract: OBJECTIVE The aim of the study was to determine the prevalence of head louse infestations and the factors affecting the rate of infestation in primary school children in Sivas. METHODS A total of 342 children (249 girls and 93 boys) were examined with a louse comb for the presence of head lice. A questionnaire with 23 questions was distributed among the pupils and their parents. RESULTS The overall infestation rate for head lice was 10.2% (n=35). The infestation rate was higher in girls (13.7%) than in boys (1.1%) (p < 0.05). Children who had been infested in the past (27.1%) were more likely to be infested than those who had not been infested previously (7.2%) (p < 0.05). The same was true for children whose family members were previously infested and those who were not (30% and 8.5%, respectively) (p < 0.05). Head lice infestation was highest (20%) in children aged 6-11 and lowest (5.3%) in children aged 13-15 (p < 0.05). The frequency of bathing and washing their hair, sharing combs, beds and towels, the hair color, hair thickness and quantity of dandruff, the number of family members and number of rooms per family member, were not significantly different between infested and non-infested children, A significant difference was found in the infestation of long haired (15.1%) compared with short haired pupils (4.5%) (p < 0.05). CONCLUSION Girls were more often infested than boys and children who were previously infested with lice, or came from families where there had been previous infestation, had a greater chance of being re-infested.

Dot-ELISA assessment of guinea pig antibody responses to repeated Dermacentor andersoni infestations.

Abstract: Acquired resistance to ixodid tick infestation is expressed by cattle and laboratory animals. Humoral factors appear to be involved in host acquired resistance to tick bite; however, specific immune responses have yet to be fully characterized. This study examined tick resistance expressed by Hartley guinea pigs upon repeated infestation with Dermacentor andersoni, and describes longitudinal development of antigen specific immunoglobulin over approximately 180 days. Guinea pigs were infested either 4 times with D. andersoni adults, or twice with nymphs. Both infestation groups, adults and nymphs, demonstrated a significant level of resistance to re-infestation, following initial exposure. Dot enzyme-linked immunosorbent assay (Dot-ELISA) was employed to detect antibody reactive with D. andersoni salivary gland antigens (SGA). Animals infested with adults had antibody that increased at a relatively constant rate until the fourth infestation, which was differentiated by a sharp increase in titer, that was maintained for approximately 2 wk. Guinea pigs that received nymph infestations had SGA-specific antibody; however, titers were lower than those in the adult infestation group. Antibody levels continued to increase approximately 80 days beyond the final (second) infestation for this group. A direct correlation between resistance and antibody titer was not evident, since resistance was relatively stable after the second infestation in both infestation groups, and tick-specific immunoglobulin levels continually increased.

Spatial Heterogeneity and Risk Maps of Community Infestation by Triatoma infestans in Rural Northwestern Argentina

Abstract: Background Fifty years of residual insecticide spraying to control Triatoma infestans in the Gran Chaco region of northern Argentina, Paraguay and Bolivia shows that vertically coordinated interventions aiming at full coverage have limited effects and are unsustainable. We quantified the spatial distribution of T. infestans domestic infestation at the district level, identified environmental factors associated with high infestation and then explored the usefulness of risk maps for the spatial stratification of interventions. Methods and Findings We performed spatial analyses of house infestation data collected by the National Chagas Service in Moreno Department, northern Argentina (1999–2002). Clusters of high domestic infestation occurred in the southwestern extreme of the district. A multi-model selection approach showed that domestic infestation clustered in areas of low elevation, with few farmlands, high density of rural houses, high mean maximum land surface temperature, large NDVI, and high percentage of degraded and deforested lands. The best model classified 98.4% of the communities in the training dataset (sensitivity, 93.3%; specificity, 95.4%). The risk map evidenced that the high-risk area only encompassed 16% of the district. By building a network-based transportation model we assessed the operational costs of spatially contiguous and spatially targeted interventions. Targeting clusters of high infestation would have reached ∼80% of all communities slated for full-coverage insecticide spraying, reducing in half the total time and economic cost incurred by a spatially contiguous strategy. Conclusions and Significance In disperse rural areas where control programs can accomplish limited coverage, consideration of infestation hot spots can contribute to the design and execution of cost-effective interventions against Chagas disease vectors. If field validated, targeted vertical control in high risk areas and horizontal control in medium to low risk areas may provide both a logistically and economically feasible alternative to blanket vertical insecticide spraying when resources are limited.