Júlio Mendes

Epidemiological aspects of head lice in children attending day care centres, urban and rural schools in Uberlândia, central Brazil

From November 1996 to March 2000, a total of 884 children between 0 and 15 years, from 11 institutions including day care centres, public urban and public rural schools in Uberlândia, State of Minas Gerais, central Brazil, were examined for head louse infestation. Childrens sex, race, age and some hairs characteristics were shown to be associated to parasite infestation. A prevalence rate of 35% was found and the highest rates were observed in black, female children, with long, dark, wavy hairs. Hairs density and thickness did not seem to influence significantly the distribution of this pediculosis in Uberlândias schoolchildren. Differences observed between the prevalence rates of head lice in children from the urban institutions suggest there is a greater epidemiological heterogeneity in this group when compared to the rural schoolchildren.

Dípteros de interesse forense em dois perfis de vegetação de cerrado em Uberlândia, MG

Os insetos podem ser de grande utilidade no auxilio de elucidacoes de crimes. Estudos de entomologia forense ainda estao restritos a poucas localidades no Brasil e sao escassos na vegetacao de cerrado. Este estudo teve por objetivo identificar as principais especies de Diptera associadas ao processo de decomposicao de carcacas de suinos Sus scrofa e o padrao de sucessao de insetos nesse tipo de substrato. Foram realizados dois experimentos nos periodos seco e umido do ano em duas areas de cerrado no municipio de Uberlândia, MG. Foram utilizadas duas carcacas de suinos em cada ambiente e periodo do ano. O processo de decomposicao foi mais lento no periodo seco, assim como a maior quantidade de insetos coletados. Diferencas na temperatura, umidade e precipitacao pluviometrica parecem ter sido os principais responsaveis pelas diferencas nos tempos de decomposicao entre os dois periodos do ano. Quatorze especies (59.467 especimes) foram coletadas nas carcacas em decomposicao. Chrysomya albiceps (Wiedemann) was the species more abundantly breed in the two periods. The other species that breed in the carcasses were: C. putoria (Wiedemann), Hemilucilia segmentaria(Fabricius), Lucilia eximia(Wiedemann) (Calliphoridae), Peckia (Pattonella) intermutans(Walker), Peckia (Squamatoides) trivitatta(Curran), Sarcodexia lambens(Wiedemann) (Sarcophagidae), Musca domestica(L.), Ophyra aenescens(Wiedemann), Stomoxys calcitransL. (Muscidae), Fannia pusio(Wiedemann), Fannia sp. (Fanniidae), Hermetia illuscens L. (Stratiomyidae) e Phoridae sp. O cerrado dessa regiao apresenta varios dipteros potenciais indicadores forenses.

Cattle Dung Breeding Diptera in Pastures in Southeastern Brazil: Diversity, Abundance and Seasonallity

Diptera that breed in undisturbed cattle droppings in pastures present great diversity and abundance, and several species are of veterinary importance and may cause economic losses. To survey the diversity, abundance and seasonality of Diptera associated to this microhabitat, 83 samples of 10 dung pats each were taken from April 1992 to April 1994 in the vicinity of São Carlos, State of São Paulo, Southeastern Brazil. A total of 46,135 Diptera belonging to 20 families and at least 51 species were found to breed in the pats. The most abundant and diverse families were Sepsidae, Muscidae, Sarcophagidae and Sphaeroceridae. In general, the abundance was higher from October to March, the warm and wet months. The importance of some Diptera, both as horn fly enemies and as cattle dung decaying agents, is discussed.

Susceptibility of Aedes aegypti (L) to the insect growth regulators diflubenzuron and methoprene in Uberlândia, State of Minas Gerais

Aedes aegypti (L) (Diptera: Culicidae) was reared in several concentrations of diflubenzuron and methoprene under laboratory conditions in Uberlândia, State of Minas Gerais, southeastern Brazil. Characteristics such as LC50 and LC95, the susceptibility of immature stages of different ages to these insect growth regulators and their residual effects were studied. The LC50 and LC95 of diflubenzuron and methoprene were 5.19 and 12.24 ppb; 19.95 and 72.08 ppb, respectively. While diflubenzuron caused great mortality in all larval instars, methoprene was more effective when the mosquito was exposed from the start of the fourth larval instar onwards. Commercial concentrations of these two insect growth regulators close to LC95 presented greater residual activity than did their respective technical formulations. The parameters were compared with those obtained elsewhere. The characteristics investigated here indicate that these insect growth regulators are effective alternatives for controlling the dengue vector in the Uberlândia region.

Dinâmica populacional de Aedes aegypti (L) em área urbana de alta incidência de dengue

Aspects of the population dynamics of Aedes aegypti were investigated from collections over a two-year period in the urban area of Uberlândia, State of Minas Gerais. The population dynamics of this mosquito were influenced by physical factors such as temperature and rainfall. High larval densities also had an influence on mosquito development.

Developmental stress by diflubenzuron in Haematobia irritans (L.) (Diptera: Muscidae)

This study aimed to assess the effect of sub-lethal concentrations of the insect growth regulator (IGR), diflubenzuron, on the body size of the horn fly Haematobia irritans (L.) and on its developmental stability, by fluctuating asymmetry (FA) analysis. Breeding media with different sub-lethal diflubenzuron concentrations and a control medium, were prepared to obtain morphometric measures on adult individuals. Principal component analysis was used to generate an index of general body size, using the correlation matrix of the original characters. Levels of FA and the multivariate index of size were compared among treatments. Contrary to the expectations, the exposure to diflubenzuron did not result in a significant and concomitant increase in the level of FA across treatments or in the number of individuals showing developmental instability. Nevertheless, a significant reduction of size due to the diflubenzuron may reflect the ability of H. irritans to perform physiological and morphological adjustments allowing phenotype compensation, at least to some extent, for stressful environmental conditions. On the other hand, the IGR may be selecting more symmetrical and resistant individuals. From the pest control point of view, the reduction of size may be a positive effect of the IGR since size is usually directly related to fitness.

Prevalence and monthly distribution of head lice using two diagnostic procedures in several age groups in Uberlândia, State of Minas Gerais, Southeastern Brazil

Some epidemiological characteristics of head lice, Pediculus capitis, were studied using two procedures: cut hair analysis and head inspection. Higher prevalence rates were observed in the middle and at the end of the school terms. Both procedures indicated that children were the main reservoir for this type of pediculosis in Uberlândia.

Effect of diflubenzuron on immature stages of Haematobia irritans (L.) (Diptera: Muscidae) in Uberlândia, State of Minas Gerais, Brazil.

Horn fly immatures were raised in media containing different concentrations of diflubenzuron in order to verify their susceptibility to this insect growth regulator (IGR). The 50% and 95% lethal concentrations of diflubenzuron for the population (LC50, LC95) were determined as well as the effect of this IGR on the different immature horn fly stages. The tests were performed using the progeny of adults collected in the field. The immatures were maintained in a growth chamber at 25.0 +/- 0.5oC and 12-12 h photoperiod. IGR concentrations of 300 ppb, 100 ppb and 50 ppb were lethal for 100% of the sample. Pupae malformation occurred in the breeding media containing different diflubenzuron concentrations. Values for LC50, LC95 (+/- 95% fiducial limits) and the slope of the regression line were respectively, 25.521 +/- 1.981 ppb, 34.650 +/- 2.001 ppb and 12.720 +/- 1.096. The third larval instar was more sensitive to the sub-lethal concentration of the product than the first and second ones were. The results indicate that this IGR can be an important tool for controlling horn fly populations as well as for managing horn fly resistance to conventional insecticides against Haematobia irritans in Uberlândia, State of Minas Gerais.

Effects of sublethal concentrations of diflubenzuron and methoprene on Aedes aegypti (Diptera: Culicidae) fitness.

The effects of sublethal concentrations of the insect growth regulators (IGRs) diflubenzuron and methoprene on some fitness components of an Aedes aegypti (L.) population in south-eastern Brazil were investigated. The fourth instar larvae of the mosquito were exposed to 20ppb methoprene and 3ppb diflubenzuron, and adult survivors were evaluated for fitness parameters, including body size and biomass, fecundity, fertility, longevity and symmetry. The sublethal concentrations had negative effects on longevity, but biomass, fecundity and fertility were not affected by either IGR. In separate experiments, A. aegypti individuals’ surviving concentrations of 2, 3 and 3.5 ppb diflubenzuron and 5, 10 and 20ppb methoprene were used for morphological analyses (size and symmetry). Diflubenzuron had negative effects on the mosquito’s body symmetry. The observed decreases in longevity and symmetry may have negative impacts on the population dynamics of A. aegypti.

Coleoptera associated with undisturbed cow pats in pastures in Southeastern Brazil

Coleoptera associated to undisturbed cattle droppings in pastures present great diversity and abundance. Several species are of primary veterinary importance for they may act as natural enemies of pest insects that breed in this habitat. To survey the diversity and abundance of Coleoptera associated to undisturbed cattle droppings, four undisturbed cattle dung pats naturally dropped in pastures and 5 cm of the soil immediately beneath them were collected almost all weekly from April 1992 to April 1994 in a farm located in the vicinity of São Carlos, State of São Paulo, Southeastern Brazil. Beetles were collected from the pats both using Berlese funnels and by allowing the beetles to emerge for 30 to 40 days. A total of 24,332 specimens belonging to 13 beetle families and at least 66 species were identified. The most abundant and diverse families were Aphodiidae, Staphylinidae and Scarabaeidae. In general, the Coleoptera were more abundant in the warmer and wet period, from October to March, with a few exceptions. The importance of the beetles, both as horn fly natural enemies and as cattle dung decaying agents, is discussed.