The green peach aphid, Myzus persicae, is a major insect pest worldwide. The parasitoid Aphidius colemani and more recently, the entomopathogenic fungus Lecanicillium muscarium strain KV01 (Mycotal ® ), have been considered as potential biological control against M. persicae.However, no studies have been carried out on the interaction between L. muscarium and A. colemani against M. persicae. This study, therefore, was conducted to determine the most effective timing of application of this fungal strain in combination with either naturally occurring or introduced parasitoids to control Myzus persicae in the laboratory and controlled field environments. In the laboratory, mummification, emergence of parasitoid adults from mummified aphids and female sex ratio of the emerging adults, were not affected when the fungus was applied 6 or 7 days after the parasitoids were added, compared with treatment with A. colemani only. Although a 40 % reduction in the female sex ratio of emerging parasitoid adults was recorded when fungi applied 3 days after the parasitoids were added, fungal application had no significant effect on longevity and fecundity of the female A. colemani F1 generation that emerged from fungus-treated aphids. In the semi-field experiment, the mean number of aphids per leaf was significantly lower in the treatment involving A. colemani in combination with L.

The green peach aphid, Myzus persicae, is a major pest worldwide. An examination of the impact of temperature, relative humidity and developmental stages of M. persicae on the efficacy of the whitefly mycoinsecticide Mycotal®, based on Lecanicillium muscarium and the effects of infection on aphid fecundity was evaluated under controlled conditions. Although this fungus can be grown at a broad range of temperatures (15-30 o C), the optimum temperature for control of M. persicae ranged between 20 and 30 o C. L. muscarium had high efficacy as a microbial control against M. persicae between 55 and 90% relative humidity. Total mortality of aphids treated with different spore dosages of L. muscarium varied according to the developmental stage: adults, fourth and third instar nymphs of proved more susceptible than first instar nymphs. Although the fungus did not affect the rate of nymph production, the reproductive period of aphids significantly decreased with increasing the spore dosage. Thus, total fecundity of treated aphids was 22.6 ± 1.1 and 31.6 ± 2.4 offspring per adult at the medium (644 ± viable spore/mm 2) and low (330 ± 40 viable spore/mm 2) dosages, compared with 45.7 ± 4.3 offspring per untreated aphid. The results suggest that L. muscarium has the potential as a biological control agent of M. persicae. However, fungal infection appears to have no sub-lethal effects on the fitness of the host's progeny.

No abstract