Spittle Maggots: Studies on Cladochaeta Fly Larvae Living in Association with Clastoptera Spittlebug Nymphs

Abstract

-Cladochaeta (Diptera: Drosophilidae) larvae live in nymphal spittle masses of New World spittlebugs (Homoptera: Cercopoidea). Cladochaeta inversa (Walker) is widely distributed on Clastoptera obtusa (Say) nymphs in eastern North America, with a mean infestation rate of 0.21 ? 0.04 (mean + SE, n = 11 surveys) immature flies per spittlebug nymph. In the Chicago area it also occurs on Clastoptera proteus Fitch nymphs with a mean infestation rate of 0.04 ? 0.01 (mean ? SE, n = 24 surveys) immature flies per nymph. Fly larvae do not appear to damage spitlebug nymphs and nymphs do not appear to resist association with larvae. Clastoptera obtusa field-reared with Cladochaeta inversa larvae were not significantly smaller or more susceptible to mortality than maggot-free controls. There were no significant size correlations between fly puparia and Clastoptera obtusa adults reared from the same spittle mass. Enzyme electrophoresis gave no evidence for incipient speciation based on host specificity, but revealed a single case (among 32 tests on 19 specimens) in which a fly larva appeared to have ingested Clasoptera proteus tissue. Cladochaeta inversa may be intermittently parasitic, with nymphal hemolymph occasionally supplementing direct ingestion of spittle-borne nutrients in a predominantly commensal relationship.