Population dynamics, life stage and ecological modeling in Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dispersal and predation behavior in larvae of Chrysomya albiceps and Chrysomya megacephala (Diptera : Calliphoridae)

Chrysomya albiceps and Chrysomya megacephala are exotic blowfly species known by producing myiasis in humans and other animals and by transmitting pathogens mechanically. C. albiceps stand out by being a facultative predator of other dipteran larvae. In this paper we investigated the influence of larval predation on the dispersal of larvae of C. albiceps and C. megacephala single and double species for three photophases. An experimental acrylic channel graduated and covered with wood shavings was used to observe the larval dispersal. The results showed that C. albiceps attacks C. megacephala larvae during dispersal and keeps an aggregated pattern close to the release point, in single and double species, independently of the different photophases. Chrysomya megacephala single species exhibited the same pattern, but in double species this was changed to a random distribution.

Spatio-temporal dynamics and transition from asymptotic equilibrium to bounded oscillations in Chrysomya albiceps (Diptera, Calliphoridae)

The sensitivity of parameters that govern the stability of population size in Chrysomya albiceps and describe its spatial dynamics was evaluated in this study. The dynamics was modeled using a density-dependent model of population growth. Our simulations show that variation in fecundity and mainly in survival has marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations. C. albiceps exhibits a two-point limit cycle, but the introduction of diffusive dispersal induces an evident qualitative shift from two-point limit cycle to a one fixed-point dynamics. Population dynamics of C. albiceps is here compared to dynamics of Cochliomyia macellaria, C. megacephala and C. putoria.

Seasonal fecundity and body size in Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae)

Neste estudo a variação sazonal da fecundidade, tamanhos de asa e tíbia, foi investigada em populações naturais de Chrysomya megacephala (Fabricius) a fim de determinar variações nas características bionômicas da espécie em função da sazonalidade. Uma trajetória temporal relativamente constante foi encontrada para fecundidade, tamanhos de asa e tíbia durante doze meses. Correlações positivas e significativas entre tamanho da asa e temperatura, tamanho da tíbia e temperatura e tamanhos da asa e tíbia foram observadas. As implicações desses resultados para a dinâmica populacional de C. megacephala foram discutidas.

Theoretical estimates of consumable food and probability of acquiring food in larvae of Chrysomya putoria (Diptera: Calliphoridae)

An indirect estimate of consumable food and probability of acquiring food in a blowfly species, Chrysomya putoria, is presented. This alternative procedure combines three distinct models to estimate consumable food in the context of the exploitative competition experienced by immature individuals in blowfly populations. The relevant parameters are derived from data for pupal weight and survival and estimates of density-independent larval mortality in twenty different larval densities. As part of this procedure, the probability of acquiring food per unit of time and the time taken to exhaust the food supply are also calculated. The procedure employed here may be valuable for estimations in insects whose immature stages develop inside the food substrate, where it is difficult to partial out confounding effects such as separation of faeces. This procedure also has the advantage of taking into account the population dynamics of immatures living under crowded conditions, which are particularly characteristic of blowflies and other insects as well.

Sex ratio and dynamic behavior in populations of the exotic blowfly Chrysomya albiceps (Diptera, Calliphoridae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Larval density, temperature and biological aspects of Chrysomya megacephala (Diptera: Calliphoridae)

Analisou-se o efeito de duas densidades larvais e duas temperaturas sobre a sobrevivência, fecundidade e tamanho corpóreo de C. megacephala em condições experimentais. Nenhum efeito simultâneo da densidade e temperatura foi encontrado sobre as variáveis investigadas em C. megacephala. Entretanto, foram observados efeitos isolados significativos da densidade e da temperatura sobre a fecundidade e tamanho corpóreo. A importância desses resultados para a dinâmica populacional de C. megacephala foi discutida.

Fecundity, body size and population dynamics of Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae)

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

Dynamics of experimental populations of native and introduced blowflies (Diptera: Calliphoridae): mathematical modelling and the transition from asymptotic equilibrium to bounded oscillations

The equilibrium dynamics of native and introduced blowflies is modelled using a density-dependent model of population growth that takes into account important features of the life-history in these flies. A theoretical analysis indicates that the product of maximum fecundity and survival is the primary determinant of the dynamics. Cochliomyia macellaria, a blowfly native to the Americas and the introduced Chrysomya megacephala and Chrysomya putoria, differ in their dynamics in that the first species shows a damping oscillatory behavior leading to a one-point equilibrium, whereas in the last two species population numbers show a two-point limit cycle. Simulations showed that variation in fecundity has a marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations and aperiodic behavior. Variation in survival has much less influence on the dynamics.

Seasonal population dynamics in Lucilia eximia (Wiedemann) (Diptera: Calliphoridae)

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

Prey choice by facultative predator larvae of Chrysomya albiceps (Diptera: Calliphoridae)

In this study we investigated predation rates on third instar larvae of Chrysomya putoria and C. megacephala by third instar larvae of C. albiceps in a two-choice situation. The highest predation rate occurred on C. putoria larvae and this result is compared to previous experiments, in which C. macellaria larvae were present. Our results suggest that, when C. macellaria is absent C. albiceps larvae attack more C. putoria than C. megacephala larvae. Prey choice decisions and its implications for introduced and native blowflies are discussed.

Larval dispersal and predation in experimental populations of Chrysomya albiceps and Cochliomyia macellaria (Diptera: Calliphoridae)

In this study we investigated the larval dispersal associated with larval predation in experimental populations of Chrysomya albiceps and Cochliomyia macellaria. Frequency distribution of sampling units (G test) in the substrate was used to evaluate variation in larval dispersal. An experimental acrylic channel (1 x 0.1 x 0.2 m) covered with wood shavings was used to observe larval dispersal prior to pupation. The acrylic channel was graduated at 0.05 m intervals, each representing a sampling unit; hence, 20 sampling units were set up. A Petri dish containing third instar larvae of single and double species was deposited at one edge of the acrylic channel allowing larvae to disperse. The number of buried pupae (0, 1, 2, n) present in each sampling unit was recorded. For double species, the number of recovered larvae of C. albiceps was similar to the number initially released on the dish Petri. on the other hand, the number of recovered larvae of C. macellaria was significantly smaller than the initially released number. The results show that C. albiceps attacks C. macellaria larvae during the larval dispersal process. The larval distribution of C. albiceps did not differ significantly from C. macellaria in double species, but it differed significantly in single species. The larval aggregation level of C. macellaria decreased when C. albiceps was present and the larval aggregation level of C. albiceps increased when C. macellaria was present. The implications of such findings for the population dynamics of these species are discussed.

Stochastic dynamics of Musca domestica (Diptera: Muscidae) and Chrysomya putoria (Diptera: Calliphoridae)

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

Taxa de desenvolvimento de Chrysomya albiceps(Wiedemann) (Diptera: Calliphoridae) em dieta artificial acrescida de tecido animal para uso forense

Forensic entomology uses biological and ecological aspects of necrophagous insects to help in criminal investigations to estimate the post-mortem interval (PMI) or to determine the cause of death. Recent papers demonstrated that the presence of toxins in decomposing tissues may alter the insect developmental rate of insects exploiting such tissues as food. Thus, preliminary tests with artificial diets in laboratory are necessary to create a database to investigate and quantify the modifications that can occur with the collected insects from a criminal scene, avoiding any errors on the PMI estimates. The present study aimed to evaluate the developmental rate of Chrysomya albiceps (Wiedemann) reared on: a) artificial diets containing animal tissues: bovine liver (D1), raw muscle (D2), stomach (D3), and chicken heart (D4); b) artificial diet without animal tissue (D5); and c) a control group (C), which had only meat. The efficiency of each substrate was assessed by immature weight gain (mg), larval developmental time, larval and pupal survival, emergence interval and adult size. D1 to D4 diets did not restrict C. albiceps development; however, larvae reared on D1 and D2 diets presented a lower adult emergence rate. D3 and control group showed similarities regarding the efficiency parameters (rate and emergence interval). Thus, the use of diet D3, artificial diet with stomach, is the most recommended.

Ultramorphological characteristics of Chrysomya megacephala (Diptera, Calliphoridae) eggs and its eclosion

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)