Spittlebug and buffelgrass responses to summer fires in Mexico

Abstract

Summer burning was used to reduce spittlebug (Aeneolamia albofasciata Lall.) populations in buffelgrass [Cenchrus ciliaris (L.) Link] on the Carbo Livestock Research Station in Sonora, Mexico. Five treatments included (1) an untreated control; (2) burning 7-14 days before the summer rains when the insect and the plant were inactive; (3) burning after the accumulation of 50 mm of summer precipitation during insect egg hatch or the second leaf stage; (4) burning between the second and third instars or early culm elongation; (5) and burning between the fifth instar and adult stages or active plant growth during the summer growing season. Summer burning after the accumulation of 50 mm of precipitation and between the egg hatch and the third instars or between the second leaf stage and early culm elongation reduced spittlebug nymph and adult populations by 100% and appeared to stimulate buffelgrass growth for 3 and 4 years post treatment. Burning at the peak of buffelgrass live biomass production effectively controlled spittlebug populations but reduced plant production by almost 50% for 4 years post-treatment. Equally detrimental was the untreated control where nymph and adult spittlebug populations killed more than 50% of the buffelgrass population. Summer fires conducted after 50 mm of precipitation were easier to control than fires conducted before the growing season when plant material was dry.