Necrophagous diptera associated with wild animal carcasses in southern Brazil

Necrophagous Diptera associated with wild animal carcasses in southern Brazil. The aim of this study was to acquire a better knowledge concerning the diversity of necrophagous Diptera that develop on wild animal carcasses. For this purpose, the decomposition of six wild animal carcasses was observed in order to collect and identify the main species of necrophagous flies associated with the decomposition process. The carcasses were found on highways near the cities of Pelotas and Capão do Leão in the initial stage of decomposition, with no significant injuries or prior larval activity. Four wild animal models were represented in this study: two specimens of Didelphis albiventris Lund, 1840; two Tupinambis merianae Linnaeus, 1758; one Nothura maculosa Temminck, 1815; and one Cerdocyon thous Linnaeus, 1766. A total of 16,242 flies from 14 species were reared in the laboratory, where Muscidae presented the greatest diversity of necrophagous species. Overall, (i) carcasses with larger biomass developed a higher abundance of flies and (ii) the necrophagous community was dominated by Calliphoridae, two patterns that were predicted from published literature; and (iii) the highest diversity was observed on the smaller carcasses exposed to the lowest temperatures, a pattern that may have been caused by the absence of the generalist predator Chrysomya albiceps (Wiedemann, 1819). (iv) An UPGMA analysis revealed a similar pattern of clusters of fly communities, where the same species were structuring the groupings.

Efficacy of entomopathogenic bacteria for control of Musca domestica.

The aim of this study was to evaluate the larvicidal activity, and sub lethal effects of entomopathogenic bacteria Brevibacillus laterosporus, Bacillus thuringiensis var. israelensis, B. thuringiensis var. kurstaki, and a commercial formulation of Bacillus sphaericus on Musca domestica. Bacterial suspensions were prepared in different concentrations and added to the diet of newly-hatched larvae which were monitored until the adult stage. The larvae were susceptible to the B. laterosporus, B. thuringiensis var. israelensis, and B. thuringiensis var. kurstaki bacteria in varied concentration levels. These bacteria have larvicidal and sub lethal effects on the development of flies, reducing both adult size, and impairing the reproductive performance of the species.

Assembly rules in muscid fly assemblages in the grasslands biome of Southern Brazil.

The distribution of muscid species (Diptera) in grasslands fragments of southern Brazil was assessed using null models according to three assembly rules: (a) negatively-associated distributions; (b) guild proportionality; and (c) constant body-size ratios. We built presence/absence matrices and calculated the C-score index to test negatively-associated distributions and guild proportionality based on the following algorithms: total number of fixed lines (F L), total number of fi xed columns (F C), and the effect of the average size of the populations along lines (W) for 5000 randomizations. We used null models to generate random communities that were not structured by competition and evaluated the patterns generated using three models: general, trophic guilds, and taxonomic guilds. All three assembly rules were tested in each model. The null hypothesis was corroborated in all F L X F C co-occurrence analyses. In addition, 11 analyses of the models using the W algorithm showed the same pattern observed previously. Three analyses using the W algorithm indicated that species co-occurred more frequently than expected by chance. According to analyses of co-occurrence and guild proportionality, the coexistence of muscid species is not regulated by constant body size ratios. In fl ies of the grasslands, no rule was identified. Yet, a consensus did emerge from our analyses: species co-occur more frequently than expected by chance, indicating that aggregation is a recurring phenomenon among flies with saprophagous adults and predatory larvae. Therefore, competition does not seem to play an important role in the determination of muscid assemblages in the grasslands in Southern Brazil.

Assembly rules in Muscid Fly assemblages in the grasslands Biome of Southern Brazil

The distribution of muscid species (Diptera) in grasslands fragments of southern Brazil was assessed using null models according to three assembly rules: (a) negatively-associated distributions; (b) guild proportionality; and (c) constant body-size ratios. We built presence/absence matrices and calculated the C-score index to test negatively-associated distributions and guild proportionality based on the following algorithms: total number of fixed lines (F L), total number of fi xed columns (F C), and the effect of the average size of the populations along lines (W) for 5000 randomizations. We used null models to generate random communities that were not structured by competition and evaluated the patterns generated using three models: general, trophic guilds, and taxonomic guilds. All three assembly rules were tested in each model. The null hypothesis was corroborated in all F L X F C co-occurrence analyses. In addition, 11 analyses of the models using the W algorithm showed the same pattern observed previously. Three analyses using the W algorithm indicated that species co-occurred more frequently than expected by chance. According to analyses of co-occurrence and guild proportionality, the coexistence of muscid species is not regulated by constant body size ratios. In fl ies of the grasslands, no rule was identified. Yet, a consensus did emerge from our analyses: species co-occur more frequently than expected by chance, indicating that aggregation is a recurring phenomenon among flies with saprophagous adults and predatory larvae. Therefore, competition does not seem to play an important role in the determination of muscid assemblages in the grasslands in Southern Brazil.

[Behavior of radial larval propagation of Muscina stabulans (Fallén) (Diptera: Muscidae) under laboratory conditions]. / Comportamento de propagação radial de larvas de Muscina stabulans (Fallén) (Diptera: Muscidae) em condições de laboratório.

Muscina stabulans (Fallén) is a synanthropic fly commonly found in decomposing animal matter. Once food resources are exhausted, larvae will disperse in search for a suitable place to pupariate or for an additional source of food. The behavior of propagation of postfeeding L3 larvae was studied by analyzing the distance of propagation, the depth of pupariation site, the pupal weight and sex ratio using a 50 cm circular arena divided in four quadrants, and filled with a 10 cm thick layer of humid sawdust. The total of 70.9% of the larvae pupariate up to 20 cm away from the arena's center, with 41.8% of them from 2.1 cm to 4.0 cm deep. Pupae that did not yield adults were lighter, and were originated by larvae that moved longer away and dug deeper to pupariate in relation to those from which adults emerged.

Comportamento de propagação radial de larvas de Muscina stabulans (Fallén) (Diptera: Muscidae) em condições de laboratório / Behavior of radial larval propagation of Muscina stabulans (Fallén) (Diptera: Muscidae) under laboratory conditions

Muscina stabulans (Fallén) is a synanthropic fly commonly found in decomposing animal matter. Once food resources are exhausted, larvae will disperse in search for a suitable place to pupariate or for an additional source of food. The behavior of propagation of postfeeding L3 larvae was studied by analyzing the distance of propagation, the depth of pupariation site, the pupal weight and sex ratio using a 50 cm circular arena divided in four quadrants, and filled with a 10 cm thick layer of humid sawdust. The total of 70.9 percent of the larvae pupariate up to 20 cm away from the arena's center, with 41.8 percent of them from 2.1 cm to 4.0 cm deep. Pupae that did not yield adults were lighter, and were originated by larvae that moved longer away and dug deeper to pupariate in relation to those from which adults emerged.