Competição larval em Chrysomya megacephala (F.) (Diptera: Calliphoridae): efeitos de diferentes níveis de agregação larval sobre estimativas de peso, fecundidade e investimento reprodutivo
Abstract:Larval competition in Chrysomya megacephala (F.) (Diptera: Calliphoridae): effects of different levels of larval aggregation on estimates of weight, fecundity and reproductive investmentIn insects that utilize patchy and ephemeral resources for feeding and egg laying, the outcome of larval competition for food resources depends on the amount of resources and the spatial distribution of immatures among patches of food. In the present study, the results of larval competition for food in Chrysomya megacephala, in… Show more
“…The larval viability rate in the gizzard homogenate diet was 73% (60 g of diet for 40 larvae = 1.5 g of diet per larva), presenting a similar rate to that reported by Godoy et al (1996), who used an artificial diet, and the rate reported by Leal et al (1982), of 73.25% at a density of 50 g of diet for 100 larvae (0.5 g of diet per larva) and at the 20 other densities tested with smaller quantities of diets fed to larvae. The diet used by Leal et al (1982) has been used by several other authors (Von Zuben et al 2000; Estrada et al 2009), and the achievement of a similar viability indicates a good result.…”
The purpose of this study was to evaluate the post—embryonic development of Chrysomya putoria (Wiedemann 1818) (Diptera: Calliphoridae) reared on a diet of gizzard or gizzard/agar homogenate, with a diet of beef used as the control. Four replicates per treatment were performed (60 mL of each diet). The gizzard (60%), distilled water, and agar homogenate were combined in a blender. Each replicate consisted of 40 newly hatched larvae of C. putoria (5th generation). Each glass beaker containing a diet was inserted into a larger flask containing sawdust, which was covered with a nylon cloth held in place by an elastic band. The larvae were weighed and stored in test tubes sealed with a nylon cloth and an elastic band. The average temperature, measured with a thermohygrograph, was 20.6 °C, and the average relative humidity was 67.7%. The variation in the mean weight of mature larvae and in the duration of the larval, pupal, and total stages (newly hatched larvae to imagoes) were analyzed by Student's t—test (α = 5%), while viability was compared by ANOVA. The sex ratio was evaluated by the chi—squared test. The average duration of the period from the larval to imago stage was 8.868 days on the beef diet, 8.676 on the gizzard diet, and 9.067 on the gizzard/agar homogenate diet. Larval survival rates on these diets were 98, 92, and 73%, respectively, while pupal viabilities were 98, 91, and 71%, respectively, and larva—to—imago viabilities were 93, 83, and 64%, respectively. The duration of the pupal period differed significantly between the blowflies reared on the beef and gizzard/agar homogenate diets. The two diets proved to be good alternatives for rearing C. putoria.
“…The larval viability rate in the gizzard homogenate diet was 73% (60 g of diet for 40 larvae = 1.5 g of diet per larva), presenting a similar rate to that reported by Godoy et al (1996), who used an artificial diet, and the rate reported by Leal et al (1982), of 73.25% at a density of 50 g of diet for 100 larvae (0.5 g of diet per larva) and at the 20 other densities tested with smaller quantities of diets fed to larvae. The diet used by Leal et al (1982) has been used by several other authors (Von Zuben et al 2000; Estrada et al 2009), and the achievement of a similar viability indicates a good result.…”
The purpose of this study was to evaluate the post—embryonic development of Chrysomya putoria (Wiedemann 1818) (Diptera: Calliphoridae) reared on a diet of gizzard or gizzard/agar homogenate, with a diet of beef used as the control. Four replicates per treatment were performed (60 mL of each diet). The gizzard (60%), distilled water, and agar homogenate were combined in a blender. Each replicate consisted of 40 newly hatched larvae of C. putoria (5th generation). Each glass beaker containing a diet was inserted into a larger flask containing sawdust, which was covered with a nylon cloth held in place by an elastic band. The larvae were weighed and stored in test tubes sealed with a nylon cloth and an elastic band. The average temperature, measured with a thermohygrograph, was 20.6 °C, and the average relative humidity was 67.7%. The variation in the mean weight of mature larvae and in the duration of the larval, pupal, and total stages (newly hatched larvae to imagoes) were analyzed by Student's t—test (α = 5%), while viability was compared by ANOVA. The sex ratio was evaluated by the chi—squared test. The average duration of the period from the larval to imago stage was 8.868 days on the beef diet, 8.676 on the gizzard diet, and 9.067 on the gizzard/agar homogenate diet. Larval survival rates on these diets were 98, 92, and 73%, respectively, while pupal viabilities were 98, 91, and 71%, respectively, and larva—to—imago viabilities were 93, 83, and 64%, respectively. The duration of the pupal period differed significantly between the blowflies reared on the beef and gizzard/agar homogenate diets. The two diets proved to be good alternatives for rearing C. putoria.
“…Interspecific interactions in blowfly system have been investigated in experiments in which population dynamics and competitive ability of the invading species C. rufiffacies and C. albiceps, and of the native species C. macellaria were analyzed (Wells & Greenberg 1992a,b,c, 1994, Wells & Kurahashi 1997, Faria et al 1999, Reis et al 1999, Von Zuben et al 2000. These investigations were attempts to gain a deeper understanding of recent blowfly biological invasion in Americas and its implications on population dynamics.…”
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.
“…On the other hand, high levels of larval aggregation may cause unfavorable conditions for the maggots (Rivers et al 2011) such as negative influence on adult female fertility and reproductive investment, maggot size on final stages of development, and weight of the resulting adults (Kamal 1958, Levot et al 1979, Von Zuben et al 2000, Ireland & Turner 2006, Reigada & Godoy 2006. Goodbrod & Goff (1990) showed that the optimal larval density for C. megacephala is 8 larvae/g of the substrate.…”
Blowflies use their sense of smell to locate oviposition substrates and their vision to direct and assist in landing decision. Blowflies' ovipositions are usually aggregated. Chrysomya megacephala (Fabricius) females, for example, prefer to lay eggs on substrates containing fresh eggs of the same species. However, it is possible that females would be capable of evaluating the substrate, reducing the size of egg cluster in sites with a high amount of eggs or larvae, or finding another site for laying their eggs, preventing the progeny from facing high competition for space and food. The present study aimed to investigate whether females of C. megacephala could distinguish and preferentially select previously infested substrates and whether females would lay their eggs attached or separate from eggs previously laid on the substrate. Behavioral measures were conducted inside cages under laboratory conditions in free-choice tests. Data analysis confirmed that C. megacephala females are able to distinguish the presence of cospecific eggs in the substrate and preferentially select previously infested substrates for egg laying, depositing their eggs separate from pre-existing large egg masses.
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