Development ofErynia conica(Zygomycetes: Entomophthorales) on the Cuticle of the Adult Black FliesSimulium rostratumandSimulium decorum(Diptera: Simuliidae)

Abstract

Aerial conidia ofErynia conicawere showered onto the wings of susceptible and nonsusceptible black fly,Simulium rostratumandSimulium decorum,respectively. Secondary type 2 conidia as opposed to type 1 conidia and primary conidia invaded the wings ofS. rostratum.The invasion process on both sexes of the host species was rapid, with 40% of the conidia germinating during the 2 hr that the wings were showered with conidia. Approximately 24% of total spores developed appressoria close to the parental spore and 79% of the appressoria developed penetration pegs in the cuticle by 9 hr postinoculation. These conidia also germinated (71%) on the abdominal cuticle ofS. rostratumby 6 hr, but no appressoria or penetration tubes were noted throughout the duration of the study. OnS. decorum,the invasive conidia exhibited delayed germination and neither formed appressoria nor did they invade the wings, but rather produced high levels of tertiary type 1 spores (26%). Cuticular lipids played a role in the infection process by triggering appressorium formation on the host, but did not seem to act as an inhibitory factor(s) on the nonhost.