Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Epizootiology of entomophthoralean fungi. Use of Zoophthora radicans (Brefeld) Batko (Zygomycotina: Entomophthorales) for the biocontrol of Epinotia aporema (Wals.) (Lepidoptera: Tortricidae) in Uruguay.

Abstract

Epinotia aporema [Gypsonoma aceriana] is the major pest species damaging forage legumes and soyabeans in Uruguay. The larvae feed on the flower buds and growing structures of birdsfoot trefoil (Lotus corniculatus), red clover (Trifolium pratense) and alfalfa (Medicago sativa) causing important losses in seed production. In 1989, a monitoring programme was started for adults using light traps and in 1991, a monitoring programme was conducted for larvae through weekly samples of stems. The sampled larvae were incubated individually until pupation or death. The occurrence of an insect pathogenic fungus, Zoophthora radicans [Erynia radicans] (Zygomycetes: Entomophthorales) was reported in 1992 among the incubated larvae. Since then, a research programme was developed which aims to obtain further basic information about this new fungus-host interaction, leading to an evaluation of the prospects for the use of Z. radicans for the control of E. aporema. Prevalence in the field showed high variation between years. Laboratory trials were conducted to multiply the pathogen in vitro and to evaluate the effect of climatic conditions on the growth and sporulation of the fungus. The strain n°2377 was selected causing high mortality among every larval stage in 2-7 days. The fungus showed the best radial growth at 25°C and the highest spore production at lower temperatures. Mortality attained in vitro varied between 9 and 54% depending on temperature. Natural substrates were assessed for multiplication of the pathogen. Mycelial growth was only observed on common and parboiled rice media in a period of time comparable to its growth on SDAY (around 14 days). High mortality rates were achieved from spore showers discharged by the inoculated rice.