Effects of insecticides used in strawberries on stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi (Hymeno

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RESEARCH ARTICLE

Effects of insecticides used in strawberries on stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi (Hymenoptera: Apidae) Bruna Piovesan 1 & Aline Costa Padilha 1 & Maíra Chagas Morais 1 & Marcos Botton 2 & Anderson Dionei Grützmacher 1 & Moisés João Zotti 1 Received: 8 May 2020 / Accepted: 20 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract The use of pesticides is considered one of the most important threats to pollinators, especially since they are widely used in agriculture for pest control. In the last years, several studies have reported severe secondary effects on various bee species, including exotic and native bees. In this study, lethal (mortality) and sublethal (locomotor activity) effects of insecticides and acaricides used in strawberries in Brazil (abamectin, novaluron, spinetoram, and thiamethoxam) were evaluated on the native stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi. The results showed that the effects varied significantly according to the pesticide, type of exposure (oral or topical), and bee species. Through oral exposure, M. quadrifasciata was more susceptible to all insecticides except for abamectin, while in topical exposure, T. fiebrigi was more sensitive. Thiamethoxam followed by spinetoram and abamectin were the most lethal, regardless of species or exposure route; novaluron was not harmful at the highest tested dose. The locomotor activity of bees was altered in the presence of sublethal doses (LC10 and LC50) of all insecticides. Spinetoram and abamectin can be as much as toxic as thiamethoxam against M. quadrifasciata and T. fiebrigi in laboratory experiments. These findings should be confirmed in field experiments to define possibilities to combine pest control and pollinator management. In crops like strawberries, the selectivity of native pollinators should be considered. Keywords Acute toxicity . Behavior effects . Native bees . Pesticides . Selectivity . Fragaria x ananassa Duch

Introduction Bees perform an important service as pollinators in a large number of agricultural interest crops as well as wild plants (Klein et al. 2007; Cresswell 2011). The honeybee Apis mellifera L., 1758, is the most widely used pollinator in commercial crops worldwide and the most often used as a model organism for nontarget toxicity studies (Minussi and Alves-dos-Santos 2007; Brittain and Potts 2011). However, in recent years, many beekeepers from Responsible Editor: Giovanni Benelli * Bruna Piovesan [email protected] 1

Department of Crop Protection, Federal University of Pelotas, 354, Capão do Leão 96010-900, Rio Grande do Sul, Brazil

2

Laboratory of Entomology, Brazilian Agricultural Research Corporation, 515, Bento Gonçalves 95701-008, Rio Grande do Sul, Brazil

different countries have been reporting unusual bee mortality resulting in high losses of honey beehives (Bortolotti et al. 2003). Therefore, the use of other bees, such as the stingless bees, has been encouraged, since these bees also contribut