Table 1. Top ten most acutely toxic insecticides to honey bees by the oral route.

Active Ingredient	Chemical Class	Environmental Half-life (days) ‡	Honey Bee Oral LD50 (μg/bee)†	Mammalian LD50* (mg/kg)
Fipronil	Pyrazole	65	0.003	92 (II)
Imidacloprid	Neonicotinoid	174	0.0037	424 (III)
Thiamethoxam	Neonicotinoid	39	0.005	1,563 (III)
Abamectin	Macrolide	1	0.0063	11 (I)
Clothianidin	Neonicotinoid	121	0.0079	>5,000 (IV)
Deltamethrin	Pyrethroid	21	0.011	>5,000 (IV)
Monocrotophos	Organophosphorous	30	0.02	23 (I)
Mevinphos	Organophosphorous	1	0.027	2.2–12 (I)
Beta-Cyfluthrin	Pyrethroid	13	0.035	11 (I)
Dinotefuran	Neonicotinoid	75	0.04	2,000 (III)

^‡ Source of half-life data provided in S1 Appendix, and is predominantly obtained from field testing and/or soil persistence.

† All oral LD50s for these active ingredients are considered “highly toxic” (<2 μg/bee) using US Environmental Protection Agency’s criteria.

* Acute mammalian toxicity category is given in parentheses: I = Highly Toxic; II = Moderately Toxic; III = Slightly Toxic; IV = Not Acutely Toxic

Sources: Half-life data S1 Appendix, Honey bee LD₅₀s S1 Appendix, and mammalian LD₅₀s US Environmental Protection Agency.