Toxicity of sediment-bound lufenuron to benthic arthropods in laboratory bioassays

Abstract

This paper deals with species sensitivity distributions (SSDs) for the lipophilic insecticide lufenuron and benthic arthropods based on sediment-spiked laboratory toxicity tests. This compound that inhibits chitin synthesis and moulting of arthropods persists in sediment. Using field-collected sediment, toxicity tests were conducted with three macro-crustaceans and six insects. The Hazardous Concentration to 5% of the tested species, the HC5 (and 95% confidence limit), derived from an SSD constructed with 10d-LC50's was 2.2 (1.2-5.7) μg/g organic carbon (OC) in dry sediment. In addition, HC5 values derived from SSDs constructed with 28d-LC10 and 28-d LC50 values were 0.13 (0.02-1.50) μg/g OC and 2.0 (1.3-5.5) μg/g OC, respectively. In 28d toxicity tests with Chironomus riparius and Hyalella azteca, a higher sensitivity was observed when using lufenuron-spiked field-collected sediment than in lufenuron-spiked artificial sediment. Overall, the non-biting midge C. riparius appeared to be a representative and sensitive standard test species to assess effects of lufenuron exposure in sediment. The Tier-1 (based on standard test species), Tier-2 (based on standard and additional test species) and Tier-3 (model ecosystem approach) regulatory acceptable concentrations (RACs) for sediment-spiked lufenuron did not differ substantially. The Tier-2 RAC was the lowest. Since to our knowledge this study is the first in the open literature that evaluates the tiered approach in the sediment effect assessment procedure for pesticides, we advocate that similar evaluations should be conducted for pesticides that differ in toxic mode-of-action.

Nanodelivery System Alters an Insect Growth Regulator’s Action Mode: From Oral Feeding to Topical Application

“…IGRs have been widely used to disturb the growth, development, and reproduction of various insect pests . Among them, lufenuron is an unsystematic insecticide belonging to the benzoyl urea class targeting the digestive system of insect pests, and it can disrupt the synthesis, polymerization, and deposition of chitin, which leads to the failure of molting and development of larvae belonging to Lepidoptera, Coleoptera, Hemiptera, Diptera, and Thysanoptera. , Chitin is not only the component of arthropods’ exoskeleton but also the cell wall of fungi, thus making lufenuron an excellent IGR toward plant pests and pathogens …”

Comparison of Species Sensitivity Distributions for Sediment‐Associated Nonionic Organic Chemicals Through Equilibrium Partitioning Theory and Spiked‐Sediment Toxicity Tests with Invertebrates

“…Therefore, if SSDs are derived based only on spiked‐sediment tests, nonstandard species must be tested. This has been exemplified by previous studies (Brock et al, 2018, 2020) and recommended by the EFSA Panel on Plant Protection Products and Their Residues (2015). In addition, standard test species in sediment tests (i.e., Hyalella azteca , Chironomus dilutus , and Chironomus riparius ) were not always the most sensitive in each SSD (Figure 1), indicating that sediment risk assessments based only on such standard species can be underprotective for other sensitive species (e.g., a mayfly, Hexagenia sp., to bifenthrin [Harwood et al, 2014] and a clam, Mercenaria mercenaria , to fluoranthene [Chung et al, 2007]; Supporting Information, Table S1).…”

“…To address this, several methods have been proposed to estimate hazardous concentrations, such as using only the data from the most sensitive taxonomic groups (e.g., insects) or using a multimodal model (Del Signore et al, 2016; Fox et al, 2021; Nagai, 2016). Although the present study and others on spiked‐sediment tests (Brock et al, 2018, 2020) have used a single log‐normal distribution SSD largely because of the limited availability of toxicity data, the proposed methods may be more beneficial in analyzing and comparing SSDs based on EqP theory and spiked‐sediment toxicity tests.…”

“…In contrast, crustaceans, in particular cladocerans, are generally less sensitive than insects to neonicotinoid insecticides (Raby et al, 2018), which were not analyzed in the present study. These sensitivity differences among taxonomic groups indicate the need to include test species belonging to various taxonomic groups in SSD estimation (e.g., Brock et al, 2018).…”

Agrotóxicos: críticas à regulação que permite o envenenamento do país

“…Efeitos tóxicos sobre organismos aquáticos (Brock et al, 2018); efeitos tóxicos severos, agudos e crônicos, sobre peixe (tambaqui) (Soares et al, 2016); aumenta a suscetibilidade de minhocas a infecções .…”