Neonicotinoid insecticides can serve as inadvertent insect contraceptives

Abstract

There is clear evidence for sublethal effects of neonicotinoid insecticides on non-target ecosystem service-providing insects. However, their possible impact on male insect reproduction is currently unknown, despite the key role of sex. Here, we show that two neonicotinoids (4.5 ppb thiamethoxam and 1.5 ppb clothianidin) significantly reduce the reproductive capacity of male honeybees (drones), Apis mellifera. Drones were obtained from colonies exposed to the neonicotinoid insecticides or controls, and subsequently maintained in laboratory cages until they reached sexual maturity. While no significant effects were observed for male teneral (newly emerged adult) body mass and sperm quantity, the data clearly showed reduced drone lifespan, as well as reduced sperm viability (percentage living versus dead) and living sperm quantity by 39%. Our results demonstrate for the first time that neonicotinoid insecticides can negatively affect male insect reproductive capacity, and provide a possible mechanistic explanation for managed honeybee queen failure and wild insect pollinator decline. The widespread prophylactic use of neonicotinoids may have previously overlooked inadvertent contraceptive effects on non-target insects, thereby limiting conservation efforts.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

“…They found that several pesticides, among them fipronil, imidacloprid, and thiamethoxam, reduced sperm viability (in vitro sperm assay). Effects on drones were also found by Straub et al (2016), who reported reduced drone life span as well as decreased sperm quality (low quantity of spermatozoa, reduced viability by 40%). Number of newly emerged adults and drone body mass was unaffected.…”

Pollination services mapping and economic valuation from insect communities: a case study in the Azores (Terceira Island)

“…Meanwhile, at the world scale, IP are becoming increasingly more vulnerable to (i) land-use intensification (Power et al 2012); (ii) use of pesticides (Kevan 1999;Suchail et al 2001;Dos Santos et al 2016;Geslin et al 2016); (iii) use of insecticides (Sánchez-Bayo et al 2016;Straub et al 2016); (iv) use of fertilizers (McLaughlin and Mineau 1995;Andersson et al 2014); (v) cultivation of some genetically modified crops (Warwick et al 2009); (vi) occurrence of biological invasions (Campbell et al 2015); (vii) climate change (Gill et al 2016;Ferreira et al 2016); and (viii) the interactions of these ecological stressors (Potts et al 2010;Vanbergen 2013). Nevertheless, it seems that intensive pastures aside, IP populations in Terceira Island are abundant and diverse in several agro-ecosystems (Fig.…”

Assessment of the toxic effect of pesticides on honey bee drone fertility using laboratory and semifield approaches: A case study of fipronil

“…Because reproductive functions are highly important for colony growth and sustainability, scientists advise that they should be taken into consideration [19,20]. However, no standardized methods are available to assess the effects of plant protection products on reproduction, whereas an increasing amount of evidence indicates that fertility has been impaired in reproducers and that this has impacted honey bee decline [20][21][22][23][24][25][26].…”