Feeding Site Specificity in Frog-biting Midges (Corethrellidae)

Abstract

Hematophagous arthropods often choose predictable feeding sites on their hosts´ body, presumably to maximize blood uptake while minimizing costs. Feeding sites can be host-specific, mediated by intrinsic host characters and/or specific preferences of the blood feeder. We investigated feeding site specificity in a community of frog-biting midges (Corethrella spp.) and frog hosts in La Gamba, Costa Rica. Midge distribution on hosts differed significantly between 12 investigated frog species, indicating that intrinsic host properties influence potential feeding sites. However, realized feeding sites were also significantly different between four investigated Corethrella morphotypes, across all hosts but also within certain shared hosts, indicating feeding site partitioning among Corethrella. We propose that the diversity of feeding sites in Corethrella-frog associations is determined by an interaction of host traits, e. g. calling site, defensive behavior or skin thickness, and midge traits, especially body size and corresponding mouthpart size/structure.

A little on the nose: A mosquito targets the nostrils of tree frogs for a blood meal

“…Feeding site specificity has also been documented in frog-biting midges (Corethrellidae), with feeding primarily occurring on the front of the face in vicinity of the nostrils for some species (e.g. Corethrella ranapungens) across multiple amphibian hosts (de Silva et al, 2014;Virgo & Eltz, 2022).…”

“…Feeding site specificity has also been documented in frog‐biting midges (Corethrellidae), with feeding primarily occurring on the front of the face in vicinity of the nostrils for some species (e.g. Corethrella ranapungens ) across multiple amphibian hosts (de Silva et al., 2014; Virgo & Eltz, 2022). However, feeding by frog‐biting midges appears to be more generalised to the entire front of the face of amphibians, with no specificity in the orientation of the midges with respect to the host, with feeding often occurring in groups whereby several midges feed on the nose of an individual simultaneously (de Silva et al., 2014; Virgo & Eltz, 2022).…”

“…Corethrella ranapungens ) across multiple amphibian hosts (de Silva et al., 2014; Virgo & Eltz, 2022). However, feeding by frog‐biting midges appears to be more generalised to the entire front of the face of amphibians, with no specificity in the orientation of the midges with respect to the host, with feeding often occurring in groups whereby several midges feed on the nose of an individual simultaneously (de Silva et al., 2014; Virgo & Eltz, 2022). In contrast, the mosquitoes we observed exhibited a stronger specificity for feeding directly at the nostril itself, while orientated in the same direction as the host, with feeding only occurring solitarily (potentially due to their large size limiting available space for aggregations to form).…”

“…Difficulty in obtaining a blood meal has been considered a reason for feeding site preferences among mosquitoes (Walker & Edman, 1985). It is possible that the nose is more advantageous for blood extraction if it is an area of thinner, softer skin tissue that allows for the easier injection of mouthparts (Virgo & Eltz, 2022). However, mosquitos are large and the length of their biting mouthparts less likely to lead to constraints in obtaining a meal from particular amphibian body regions when compared to smaller biting insects such as midges that also show site preferences (Barton et al., 2023).…”

The Mouthparts of Female Blood-Feeding Frog-Biting Midges (Corethrellidae, Diptera)

“…This is supported in Corethrella spp. by observed higher (non-acoustic) levels of host specialization, including the choice of host species and/or a specific feeding site on a host [ 19 ] ( Figure 1 ). Like many other biting Diptera, female frog-biting midges rely on vertebrate (i.e., frog) blood to produce their eggs [ 12 , 18 , 20 , 21 ].…”