Effects of insecticides on mortality, growth and bioaccumulation in black soldier fly (Hermetia illucens) larvae

PLoS One. 2021 Apr 21;16(4):e0249362. doi: 10.1371/journal.pone.0249362. eCollection 2021.

Abstract

Residues of persistent insecticides may be present in the substrates on which insects are reared for food and feed, which may affect insect growth or survival. In addition, insecticidal substances may bio-accumulate in reared insects. The objective of this study was to assess potential effects of selected insecticides on the growth and survival of black soldier fly larvae (BSFL, Hermetia illucens) and on their safety when used as animal feed. Six insecticides (chlorpyrifos, propoxur, cypermethrin, imidacloprid, spinosad, tebufenozide) with different modes of action were tested in two sequential experiments. Cypermethrin was also tested with the synergist piperonyl butoxide (PBO). Standard BSFL substrate was spiked to the respective maximum residue level (MRL) of each insecticide allowed by the European Union to occur in feed; and BSFL were reared on these substrates. Depending on the observed effects in the first experiment, spiked concentrations tested in the second experiment were increased or reduced. At the concentrations applied (1 and 10 times MRL), three of the six tested substances (chlorpyrifos, propoxur, tebufenozide) did not affect the survival or biomass growth of BSFL, compared to the control (non-spiked) treatments. At MRL, imidacloprid stimulated the growth of BSFL compared to the controls. Spinosad and cypermethrin at the MRL level negatively affected growth and survival. The effects of cypermethrin appeared to be augmented by addition of PBO. A mean bio-accumulation factor of ≤0.01 was found in both experiments for all substances-except for cypermethrin, which was comparatively high, but still below 1 (0.79 at 0.1 mg/kg). The lack of accumulation of insecticides in the larvae suggests that there is no risk of larval products being uncompliant with feed MRLs. However, we conclude that insecticides present in substrates may affect growth and survival of BSFL. More research on a larger variety of substances and insect species is recommended.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Feed / analysis
  • Animals
  • Bioaccumulation / drug effects*
  • Diptera / growth & development*
  • Diptera / metabolism*
  • Insecticides*
  • Larva / growth & development*
  • Larva / metabolism*

Substances

  • Insecticides

Grants and funding

This project was funded by the Netherlands Ministry of Economic Affairs (further: The Ministry) through a Public-Private Partnership project (“Controlling the safety of insects for food and feed”) of the Topsector AgriFood (TKI-AF-15220). The Ministry had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The commercial entities within the project consortium were: Proti-Farm R&D, BV; Protix Biosystems; Bestico B.V., and; ForFarmers. With the exception of Bestico B.V., the commercial entities in the consortium had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Bestico B.V. uses black soldier fly larvae to convert biomass into protein and oil for feeding purposes, and fertilizers. Bestico B.V. provided in-kind contribution to the project primarily in the form of labour costs for author L.Z., who assisted in the execution of experiments, which were performed at the premises of that company under supervision of the corresponding author. The specific roles of this author are articulated in the ‘author contributions’ section. Bestico B.V. otherwise had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.