Table 1.

Potential routes of pesticide exposure and the expected probability of exposure via those routes (0 = no probability, 1 = low probability, 2 = moderate probability, 3 = high probability, 4 = very high probability) for different life stages and castes of bumble bees (Bombus spp.) and honey bees (Apis mellifera L.).

			Probability of Pesticide Exposure*
Exposure Route	Substrate	Life Stage/Caste	Bumble Bees	Honey Bees
Bodily Contact	air particles (dust or spray)	foraging worker	4	4
		non-foraging worker	0	0
		queen	4	1
		larva	0	0
	plant surface residues	foraging worker	4	4
		non-foraging worker	0	0
		queen	4	0
		larva	0	0
	wax residues	foraging worker	1	1
		non-foraging worker	1	3
		queen	1	3
		larva	3	4
	soil residues	foraging worker	1	0
		non-foraging worker	1	0
		queen	2	0
		larva	1	0
Oral	nectar	foraging worker	4	4
		non-foraging worker	3	3
		queen	4	1
		larva	4	4
	pollen	foraging worker	4	1
		non-foraging worker	3	3
		queen	4	1
		larva	4	4
	water	foraging worker	2	4
		non-foraging worker	0	1
		queen	1	1
		larva	0	0
	guttation fluid	foraging worker	0	1
		non-foraging worker	0	1
		queen	0	1
		larva	0	0
	honey dew	forager	1	4
		non-forager adult	0	2
		queen	1	2
		larva	0	0

^*Rankings were assigned by bee experts based on the developmental, reproductive, and behavioral traits of each taxon.