Mortality of Metopolophium dirhodum (Homoptera: Aphididae) caused by strains of Erynia neoaphidis (Entomophthorales: Entomophthoraceae) from Slovakia and Greece

Abstract

The aim of the study was to test isolates of <I>Erynia neoaphidis</I> originating from Slovakia and Greece for infectivity to <I>Metopolophium dirhodum</I>, and evaluate selected strains for their infectivity at different temperatures. For alatae, an LC<SUB>50</SUB> (number of spores/mm<SUP>2</SUP>) from 109.97 to 230.90 was calculated for the Slovakian strain and of 218.9 for the Greek strain. For apterae, the LC<SUB>50</SUB> was 82.2–194.5 for the Slovakian strain and 367.2 for the Greek strain. The temperature during the incubation period influenced mortality and length of life cycle of the fungus. Lower temperature decreased the mortality and extended the incubation time. With the Slovakian strain and at 22°C, the highest proportion of individuals killed by the fungus was recorded on the third day of incubation (47.8% of the alatae and 49.9% of the apterae), while at 11°C most individuals died on the seventh day (55% and 37.5% of alatae or apterae, respectively). With the Greek strain and at 22°C, the highest proportion of individuals killed was recorded on the fourth day of incubation (40.6% of alatae and 57.9% of apterae). A lower incubation temperature (11°C) prolonged the life cycle and most apterae killed by this strain were recorded on the ninth day (35%), while the highest proportion of killed alatae was recorded on the tenth day (42.8%).