Digestibility of black soldier fly larvae (Hermetia illucens) fed to leopard geckos (Eublepharis macularius)

PLoS One. 2020 May 11;15(5):e0232496. doi: 10.1371/journal.pone.0232496. eCollection 2020.

Abstract

Black soldier fly (BSF) larvae have been marketed as an excellent choice for providing calcium to reptiles without the need of dusting or gut loading. However, previous studies have indicated that they have limited calcium digestibility and are deficient in fat soluble vitamins (A, D3, and E). In this feeding and digestibility trial, 24 adult male leopard geckos were fed one of three diets for 4 months: 1) whole, vitamin A gut loaded larvae; 2) needle pierced, vitamin A gut loaded larvae; or 3) whole, non-gut loaded larvae. Fecal output from the geckos was collected daily and apparent digestibility was calculated for dry matter, protein, fat, and minerals. There were no differences in digestibility coefficients among groups. Most nutrients were well digested by the leopard geckos when compared to previous studies, with the exception of calcium (digestibility co-efficient 43%), as the calcium-rich exoskeleton usually remained intact after passage through the GI tract. Biochemistry profiles revealed possible deficits occurring over time for calcium, sodium, and total protein. In regards to vitamin A digestibility, plasma and liver vitamin A concentrations were significantly higher in the supplemented groups (plasma- gut loaded groups: 33.38 ± 7.11 ng/ml, control group: 25.8 ± 6.72 ng/ml, t = 1.906, p = 0.04; liver- gut loaded groups: 28.67 ± 18.90 μg/g, control group: 14.13 ± 7.41 μg/g, t = 1.951, p = 0.03). While leopard geckos are able to digest most of the nutrients provided by BSF larvae, including those that have been gut loaded, more research needs to be performed to assess whether or not they provide adequate calcium in their non-supplemented form.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Feed / analysis*
  • Animal Nutritional Physiological Phenomena
  • Animals
  • Calcium, Dietary / administration & dosage
  • Calcium, Dietary / analysis
  • Calcium, Dietary / pharmacokinetics
  • Diet
  • Digestion
  • Larva / chemistry
  • Liver / metabolism
  • Lizards / physiology*
  • Male
  • Nutritive Value
  • Simuliidae* / chemistry
  • Vitamin A / administration & dosage
  • Vitamin A / pharmacokinetics

Substances

  • Calcium, Dietary
  • Vitamin A

Grants and funding

Primary funding for this study was provided to KB and MM by the Louisiana State University VCS Corp grant (#8262). Additional support was provided by Fluker Farms, Inc. (flukerfarms.com) and Abaxis, Inc. (abaxis.com). The funder (Abaxis, Inc.) provided support in the form of research materials and did not have any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The funder (Fluker Farms, Inc.) provided support in the form of materials, funding, and salary to author [KB], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section.