Acute toxicity of the insecticide abamectin and the fungicide difenoconazole (individually and in mixture) to the tropical stingless bee Melipona scutellaris

Abstract

Stingless bees have been recognized as essential plant pollinators and producers of various natural products in neotropical areas. Research into the potential risks of pesticides they may be exposed to in agricultural fields, however, remains meagre. Especially the toxicity of pesticide mixtures likely to occur under real-world conditions and that are likely to exert synergetic effects has been poorly studied. The aim of the present study was therefore to evaluate the single and mixture acute contact and oral toxicity of commercial products containing the insecticide abamectin and the fungicide difenoconazole in laboratory bioassays with the Brazilian native stingless bee Melipona scutellaris. In addition, a comparison of the insecticide sensitivity of stingless bees relative to the honeybee Apis mellifera was made based on previously published toxicity data. Except for oral exposure to abamectin, M. scutellaris appeared to be more sensitive that A. mellifera in the single compound toxicity tests. A difenoconazole concentration at the NOEC (no observed effect concentration) level indicated a synergetic toxic interaction with abamectin. A sensitivity comparison based on published toxicity data for A. mellifera and stingless bees indicated several insecticidal modes of action having a high relative sensitivity to stingless bees that need especial consideration in future studies. The research findings highlight the need for testing native bee species and environmentally relevant pesticide mixtures in risk assessments to avoid underestimation of potential risks to bee populations and the subsequent loss of pollination ecosystem services.

Amazonian stingless bees: lethal concentration and mortality after exposure to insecticide in Melipona interrupta Latreire, 1811 (Hymenoptera: Apidae)

“…The data from this study were validated by the results of tests with the positive control Dimethoate AS, which is a reference for toxicity standards and indicated the sensitivity of M. interrupta bees to its active ingredient. The CL50 for Dimethoate recorded here was the lowest among Melipona bees compared to available data in the literature for Melipona quadrifasciata Lepeletier, 1836 (Hymenoptera: Apidae) (Piovesan et al 2020) and Melipona scutellaris Latreille, 1811 (Hymenoptera: Apidae) (Brigante et al 2021) (Table 1). It was also lower than for non-Melipona bees, such as Scaptotrigona postica (Latreille, 1807) (Hymenoptera: Apidae) (Jacob et al 2019b).…”

“…Data related to toxicity tests using Thiamethoxam on stingless bees are still scarce. The information available for this group of bees is restricted to a few species such as M. scutellaris (Miotelo et al 2021;Brigante et al 2021), S. bipunctata (Moreira et al 2018), T. angustula (Jacob et al 2019a), M. quadrifasciata and Trigona fiebrigi (Schwarz, 1938) (Piovesan et al 2020. When it comes to Amazonian stingless bee species, the data from this study are unprecedented as there are no bibliographic records of research on the toxicity of chemical agents related to effects of insecticides with Amazonian meliponinios, most likely due to these species occurring in regions that are not extensively agricultural in tropical climate countries, and it is known that the main toxicity studies have been conducted in temperate climate countries (Moraes et al 2000).…”

Identification of antiparasitic drug targets using a multi-omics workflow in the acanthocephalan model

“…Thus, application of Startect against fish-parasitizing acanthocephalans seems feasible. On the other hand, the second active ingredient of Startect, abamectin, has insecticide and acaricide activity [83,84]. Thus, dissipation of Startect into the environment might be problematic and the mere administration of derquantel might be the better choice in fish.…”

Ultrastructural Changes in the Midgut of Brazilian Native Stingless Bee Melipona scutellaris Exposed to Fungicide Pyraclostrobin

“…Due to the inhibition of mitochondrial respiration [ 33 ], the fungicide pyraclostrobin can affect essential functions of bee physiology. A few studies have shown the side effects of fungicides on non-target stingless bees [ 34 , 35 , 36 , 37 , 38 ], but there is still a considerable gap between insecticide and fungicide studies [ 25 ].…”