title: Different acute toxicity of fipronil baits on invasive Linepithema humile supercolonies and some non-target ground arthropods.
abstract: Fipronil is one of the most effective insecticides to control the invasive ant Linepithema humile, but its effectiveness has been assessed without considering the genetic differences among L. humile supercolonies. We hypothesized that the susceptibility of the ant to fipronil might differ among supercolonies. If so, dosage and concentration of fipronil may need to be adjusted for effective eradication of each supercolony. The relative sensitivities of four L. humile supercolonies established in Hyogo (Japan) to fipronil baits were examined based on their acute toxicity (48-h LC(50)). Toxicities of fipronil to seven ground arthropods, including four native ant species, one native isopoda, and two cockroaches were also determined and compared to that of L. humile supercolonies using species sensitivity distributions. Marked differences in susceptibility of fipronil were apparent among the supercolonies (P < 0.008), with the 'Japanese main supercolony' (271 μg L(-1)) being five to ten times more sensitive to fipronil than other colonies (1183-2782 μg L(-1)). Toxicities to non-target species (330-2327 μg L(-1)) were in the same range as that of L. humile, and SSDs between the two species groups were not significantly different (t = -1.389, P = 0.180), suggesting that fipronil's insecticidal activity is practically the same for L. humile as for non-target arthropods. Therefore, if the invasive ant is to be controlled using fipronil, this would also affect the local arthropod biodiversity. Only the 'Japanese main supercolony' can be controlled with appropriate bait dosages of fipronil that would have little impact on the other species.
authors.affiliation: Faculty of Agriculture, KINDAI University, 3327-204 Nakamachi, Nara, 631-8505, Japan, awayotou@hotmail.com.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hayasaka
authors.forename: Naoki
authors.initials: N
authors.lastname: Kuwayama
authors.forename: Azuma
authors.initials: A
authors.lastname: Takeo
authors.forename: Takanobu
authors.initials: T
authors.lastname: Ishida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mano
authors.forename: Maki N
authors.initials: MN
authors.lastname: Inoue
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
authors.forename: Francisco
authors.initials: F
authors.lastname: Sánchez-Bayo
authors.forename: Koichi
authors.initials: K
authors.lastname: Goka
authors.forename: Takuo
authors.initials: T
authors.lastname: Sawahata
mesh_terms: D000818:Animals; D001000:Ants / Q000187:drug effects* / Q000235:genetics; D003058:Cockroaches / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology* / Q000633:toxicity; D058865:Introduced Species; D033321:Isopoda / Q000187:drug effects*; D007564:Japan; D011720:Pyrazoles / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D007306:Insecticides; D011720:Pyrazoles; C082360:fipronil