SOLENOPSIS (HYMENOPTERA, FORMICIDAE) FIRE ANT REACTIONS TO ATTACKS OF PSEUDACTERON FLIES (DIPTERA, PHORIDAE) IN SOUTHEASTERN BRAZIL

We studied the responses of Solenopsis fire ants to Pseudacteon phorid fly attacks in southeastern Brazil. The presence of these phorid parasites triggered a suite of phorid-specific defense responses including reduced foraging, bait guarding, a curled defensive posture, and general colony immobility. The existence of these phorid-specific defenses indicates that Pseudacteon phorids exert substantial evolutionary pressure on South American fire ant populations.

Duration of Protopolybia exigua exigua (de Saussure) nests and related aspects as influenced by phorid fly infestation (vespidae, polistinae, epiponini)

The main characteristics of 55 nests of Protopolybia exigua exigua were periodically evaluated in Ribeirão Preto, southeastern Brazil. Although the queens' life-span can eventually reach one year, nests barely thrive for six months because most of them are periodically invaded by the scavenger phorid fly, Megaselia aff. picta. Under heavy infestation the adult wasp population partially closes the nest entrance, migrates and constructs a new nest in the neighborhood. Afterwards the old-nest's entrance can be completely closed by the wasps which results in blocking the parasitoid flies inside. In the tropics, predation by ants is considered the main selective pressure which shaped most of the bionomic characteristics of Polistinae wasps. It is suggested that Megaselia can easily overcome the usual wasps defensive tactics just because they are so specialized against ants. Aerial raids, fast erratic-jerking movements, rapid and efficient oviposition behavior, etc. can eventually turn Megaselia into a very important enemy of some social wasps.

Are light traps baited with kairomones effective in the capture of Lutzomyia longipalpis and Lutzomyia intermedia? An evaluation of synthetic human odor as an attractant for phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparison of two methods (visual estimates and filming) for counts of horn flies (Haematobia irritans irritans) (L.) (Diptera : Muscidae)

Visual estimates are generally used for counts of horn flies, Haematobia irritans (L.) and play an important role as an instrument to quantify fly populations in scientific studies. In this study, horn fly counts were performed on 30 Nelore steers in the municipality of Aracatuba, SP Brazil, from January to December 1998. Flies were counted weekly by two methods: the estimate method whereby estimates of the number of flies on one side of the animal are obtained by visual observation, and the filming method whereby images of flies from both sides of the animal are recorded with a video camera. The tape was then played on a videotape recorder coupled to a television and the flies were counted on the screen. Both methods showed variations in horn fly population density during the period studied. However, significant differences (p < 0.05) were observed between the two methods with the filming method permitting the visualization of a larger number of flies than the estimate method. In addition, the filming method permitted safe and reliable counts hours after the images were taken, with the advantage that the tape can serve as an archive for random re-counts. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Variation in population density of horn flies (Haematobia irritans irritans) (L.) (Diptera : Muscidae) in Nellore cattle (Bos indicus)

The population density of horn flies was evaluated in the year 1998 in the municipality of Aracatuba, São Paulo Brazil, in relation to temperature and rainfall conditions. Two lots of 30 Nellore steers (Bos indicus) were used which had no insecticidal treatment and were naturally infested with horn flies. The infestations were assessed by two counting methods, i.e., the traditional estimate method and the filming method. The highest fly frequencies were recorded in spring, summer, autumn and the lowest frequencies were recorded in winter. The increase in fly number was positively correlated (P < 0.05) with rainfall. (C) 2003 Elsevier B.V. All rights reserved.

Spatial and temporal population interactions between the parasitoids Cotesia flavipes and Tachinidae flies: considerations on the adverse effects of biological control practice

Biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid Cotesia flavipes, the decrease of D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Recently, the native tachinid fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in the success. Here, we investigated the spatial and temporal population interactions between C. flavipes and the tachinid flies, and provide a critical analysis of the biological control practice, focusing on the undesirable effects of introductions of exotic natural enemies. To investigate these questions, a large data set comprising information from two sugarcane mills located in the state of São Paulo, Brazil (Barra and Sao Joao Mills), was analysed. Analysis of the correlation between C. flavipes and tachinid fly population densities through time revealed that such populations were inversely correlated in the Sao Joao Mill and not correlated in the Barra Mill. Logistic regressions were computed to investigate the proportion of sites occupied by the parasitoid species at both mills as a function of time. An increasing trend in the proportion of sites occupied by C. flavipes was observed, with a concomitant decrease of the sites occupied by tachinid flies. This effect was more intense in the Sao Joao Mill. Thus, there is a convincing possibility that constant releases of C. flavipes decreased the tachinid fly populations, resulting in an undesirable effect of biological control practice.

Foraging by Polybia (Trichothorax) ignobilis (Hymenoptera, Vespidae) on flies at animal carcasses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Marking with pigments for identification of flies in experimental populations of Megaselia scalaris Loew

A técnica de marcação de insetos de Tadei & Mourão (1976) é, até o momento, o único método experimental que possibilita determinar a idade real de cada indivíduo na população e, conseqüentemente, determinar a estrutura etária da mesma. Para isto propomos um aprimoramento dessa técnica, utilizada aqui para determinar a estrutura etária de populações da linhagem geográfica SR do díptero forídeo Megaselia scalaris Loew, mantidas pela técnica da transferência seriada em câmaras com temperatura constante de 25 ± 1,0ºC e 20 ± 1,0ºC. O estabelecimento da estrutura etária permitiu calcular a longevidade real das moscas e detectar o efeito ambiental temperatura, sendo fator determinante neste trabalho a marcação dos insetos, pois se não o fosse, teríamos somente estimativas e, dependendo do erro cometido na estimação, o efeito do fator de interesse (temperatura) poderia não ser detectado.

Comparative cytogenetic study in Muscidae flies

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

PRODUCTIVITY IN MASS CROSSES OF DROSOPHILA-STURTEVANTI - A COMPARATIVE-STUDY OF LABORATORY STOCKS AND RECENTLY COLLECTED FLIES

Drosophila sturtevanti from several geographic origins were analyzed for their capacity to intercross and to yield progeny. Mass intercrosses involving laboratory stocks and recently collected strains were fertile, which suggests that the genetic differentiation among these geographically isolated populations did not affect their reproductive patterns sufficiently to lead to reproductive isolation. Analysis of the number of progeny (productivity) in intracrosses and intercrosses was informative as to the amount of variation this feature exhibits in the laboratory stocks and in the recently collected strains. Also laboratory stocks and recently collected flies shared a positive correlation in that the greater the control productivity of a strain the greater the number of its intercrosses which exhibited reduced productivity.

Variability of esterase patterns in adult flies of the saltans species group of Drosophila (subgenus Sophophora)

Esterases are known for their involvement in several physiological processes and high degree of polymorphism, in many organisms. Such polymorphism has been used to characterize species and species groups and to study genetic changes occurred in their evolutionary history. In the present study, the esterase patterns of 19 strains from 10 species representative of the five subgroups of the saltans species group were analyzed using polyacrylamide gel electrophoresis and alpha- and beta- naphthyl acetates as substrates. Fifty-one esterase bands were detected and classified as 31 alpha-esterases, 18 beta-esterases and two alpha/beta-esterases. on the basis of the inhibition patterns using Malathion and eserine sulfate, 34 bands were classified as carboxylesterases, 14 as acethylesterases and three as cholinesterases. Ten gene loci were tentatively established on the basis of data on band position in the gel, substrate preference and inhibition pattern. Twenty bands were species-specific, the remaining being shared by species from the same or different subgroups. Bands detected exclusively in males and bands with a different frequency or degree of expression between sexes were also detected. In the gels prepared for analysis of gene expression in the body parts (head, thorax and abdomen), the degree of expression of the beta-esterases was higher in the thorax, while the alpha-esterases were expressed predominantly in the abdomen and thorax. A global view of the data available at present on the esterases of the species from the saltans group and their degree of polymorphism are presented, as well as the possibility of using some beta-esterases, because of their characteristics in the gels, as markers for species identification.

Wolbachia in Anastrepha Fruit Flies (Diptera: Tephritidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Frugivorous flies (diptera: Tephritidae and lonchaeidae) and native parasitoids (hymenoptera) associated with pouteria caimito (sapotaceae) in Brazil

This study presents new reports on frugivorous flies and their parasitoids associated with the fruits of Pouteria caimito Radlk. (Sapotaceae), a plant native to the Amazon region. In addition to the new reports, this study also presents the infestation and parasitism rates, for dipterous and hymenopteran parasitoids, respectively.

Molecular detection of the blood meal source of sand flies (Diptera: Psychodidae) in a transmission area of American cutaneous leishmaniasis, Parana State, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)