PDF《Drone exposure to the systemic》

1 Drone exposure to the systemic insecticide Fipronil indirectly impairs queen reproductive potential Guillaume?Kairo1 , Bertille?Provost2 , Sylvie?Tchamitchian1 , Faten?BenAbdelkader1,3 , Marc?Bonnet1 , Marianne?Cousin1 , Jacques?Sénéchal1 , Pauline?Benet2 ,André?Kretzschmar4 , Luc?P.

?Belzunces1 & Jean-Luc?Brunet1 A species that requires sexual reproduction but cannot reproduce is doomed to extinction.The important increasing loss of species emphasizes the ecological significance of elucidating the effects of environmental stressors, such as pesticides, on reproduction. Despite its special reproductive behavior, the honey bee was selected as a relevant and integrative environmental model because of its constant and diverse exposure to many stressors due to foraging activity.The widely used insecticide Fipronil, the use of which is controversial because of its adverse effects on honey bees, was chosen to expose captive drones in hives via syrup contaminated at 0.1?μg/L and gathered by foragers. Such environmental exposure led to decreased spermatozoa concentration and sperm viability coupled with an increased sperm metabolic rate, resulting in drone fertility impairment. Subsequently, unexposed queens inseminated with such sperm exhibited fewer spermatozoa with lower viability in their spermatheca, leaving no doubt about the detrimental consequences for the reproductive potential of queens, which are key for colony sustainability.These findings suggest that pesticides could contribute to declining honey bee populations through fertility impairment, as exemplified by Fipronil. More broadly, reproductive disorders should be taken into consideration when investigating the decline of other species. Over recent decades, Earth has been experiencing a major crisis due to an alarming rate of species loss, suggest- ing a sixth mass extinction1 . In this context, more than 25% of studied plant and animal species are threatened2 . Among pollinating insect species, data available from several studied bee species, such as bumble bees and honey bees, have shown the existence of some cases not only of population decline but also of general or relatively localized extinction3 . The anthropogenic loss of species is the result of major threats, such as the exploitation of resources, the destruction and fragmentation of habitats, the introduction of invasive species, and the spread of diseases and industrial or agrochemical pollutants1,4 . Two stressors in particular, pesticides and diseases, are known to disrupt reproductive function, which is essential for species survival. Some of these environmental stressors can directly disrupt fertility in humans, as observed during the last century5 , either directly or through the endocrine system, which plays a central role in reproductive functions6 . Such reproductive disorders have been reported in many species other than humans7 , and especially in some insects, manifested by mating behav- ior and fertility impairments8C12 , suggesting the potential for similar fertility effects in the honey bee (Apis mel- lifera L.). Honey bees are social insects of great economic and ecological interest, and declining populations have been reported over the last three decades13,14 . Among the suspected causes of this decline14 , queen failure appears to be particularly significant15C17 . The symptoms of this phenomenon include the following: decreases in or an absence of egg laying;

the appearance of a lacunar brood, i.e., an abnormal brood surface exhibiting scattered empty cells;

the excessive laying of unfertilized eggs, resulting in drone births;