Sampling bias in sex ratio and ovarian maturation of Calliphoridae and Mesembrinellidae (Diptera): influence of trap height and bait type in the Brazilian Amazon.

Calliphoridae and Mesembrinellidae flies play a key role in nutrient cycling and environmental sanitation. Their distribution is shaped by vertical resource availability and species-specific biological traits. Understanding the efficiency and selectivity of sampling methods is essential to reveal distribution patterns and corrected sampling biases, enabling more accurate estimates of population density and resource use. We assessed the abundance of calliphorids and mesembrinelids females and males in traps with two types of baits (bovine lung and fermented banana) exposed at two heights (0.6 m and 10 m) above the ground, as well as the ovarian development of females in each treatment. Statistically significant differences were observed in sex ratios and ovarian development. Females of Calliphoridae and Mesembrinellidae in vitellogenic stages were more abundant in the protein baits at 0.6m above the ground, while male calliphorids predominated in banana baits irrespective of height. Additionally, male mesembrinelids were more abundant in banana baits placed at 10m above the ground. The results of this study provide important insights into the biological patterns of the two families of sarcosaprophagous flies, revealing potential reproductive substrates, the efficiency of different sampling methods, and the importance of considering the interaction between sexual behavior, physiological state, and resource availability.