Egyptian Journal of Biological Pest Control, 24(2), 2014, 379-386 Pathogenicity of Entomopathogenic Fungi to the Green Peach Aphid Myzus persicae Sulzer (Aphididae) and the European Tarnished Bug Lygus rugulipennis Poppius (Miridae) François Lefort * ; Dominique Fleury ** ; Isabelle Fleury * ; Cyrielle Coutant * ; Stefan Kuske *** ; Patrik Kehrli **** and Pascal Maignet ***** * Plants and Pathogens Group, Institute Earth Nature Environment, Hepia, University of Applied Sciences Western Switzerland; 1202 Geneva; Switzerland. ** School of Engineering at Changins, route de Duillier 50, 1260 Nyon; Switzerland. *** Agroscope, Institute for Plant Production Sciences IPS, Schloss 1, 8820 Wädenswil, Switzerland. **** Agroscope, Institute for Plant Production Sciences IPS, route de Duillier 50, 1260 Nyon, Switzerland. ***** InVivoAgroSolutions; 83 avenue de la Grande Armée, 75782 Paris Cedex 16, France. (Received: September 17, 2014 and Accepted: October 12, 2014) ABSTRACT To reduce economic losses, producers have no choice than controlling pests by chemical insecticides with their negative impact on the environment as well as on beneficial organisms. In this context, efficient and selective biological control agents such as entomopathogenic fungi should be integrated in pest management strategies. Screening experiments showed the pathogenicity of 16 fungal strains belong to the species Beauveria bassiana (Balsamo-Crivelli) Vuillemin, B. brongniartii (Sacc.) Petch, Metarhizium anisopliae (Metchnikoff) Sorokin, Lecanicillium lecanii (Zare and Gams) and Paecilomyces fumosoroseus Vassiljevsky against the two plant sap sucking pests, the green peach aphid, Myzus persicae Sulzerand and the European tarnished bug, Lygus rugulipennis Poppius. Bioassays established on treated Chinese cabbage leaves and bean pods for M. persicae and L. rugulipennis, respectively, allowed to evaluate the most pathogenic strains for controlling each pest. The two strains ART41 and ART2580 of B. bassiana showed highest pathogenicity on M. persicae with a mortality rate of 92 and 98%, respectively, seven days post treatment. Mortality rates of L. rugulipennis reached 92 and 98% seven days after treatment for the B. bassiana strains ART2580 and ART360BB, respectively. These results should be confirmed in open field experiments by exposing both insects to the suggested B. bassiana strains. Key words: Entomopathogenic fungi; Beauveria bassiana; Metarhizium anisopliae;; Lecanicillium lecanii; Paecilomyces farinosus; Myzus persicae; Lygus rugulipennis; Biological control. INTRODUCTION Chemical control with broad spectrum insecticides has resulted negative impacts on the environment as well as on beneficial organisms in the agroecosystem. Adverse effects of such pesticides on human health and environment are well documented (Yeo et al., 2003), leading to a reduction of registered active ingredients for pest control. Furthermore, consumers exert an increasing pressure for reaching minimum pesticide residues in food (Vu et al., 2007). The use of Biological Control Agents (BCAs) should therefore be more widely integrated in strategies to control the damage caused by pests. Entomopathogenic fungi are particularly interesting BCAs since they are usually specific and consequently rarely harmful to beneficial organisms. Fungal pathogens have considerable advantage to avoid the problem of chemical residues and could be the replacements of choice for growers in order to reduce economic losses caused by pests. Plant sap sucking insects such as aphids and true bugs are significant pests on arable and perennial crops. They are found throughout the world where they can build up high population densities. Moreover, they are frequently polyphagous and some of them are also powerful vectors of viral and bacterial plant diseases (Sylvester, 1980). Two major representatives of them are the green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae) and the European tarnished bug, Lygus rugulipennis Poppius (Hemiptera: Miridae). Myzus persicae (Down et al., 2009), feeds on a wide range of crops including peach trees as well as species of Brassicae and Solanaceae. It is generally the cause of decreased growth and necrosis of wounded tissues. It reproduces asexually in large numbers, up to 15 generations per year and may transmit at least 24 harmful plant viruses (e.g.,the potato Y virus or potato leaf roll virus and various mosaic viruses) as well as more than 100 plant diseases in more than 50 plant families including major crops such as potatoes, beans, sugar beet and brassics (Van Den Heuvel, 1991 and Yeo, 2000). Asexual reproduction in M. persicae potentially allowed it to quick develop resistances against the chemical insecticides (Bass et al., 2014). All those issues force to the development of alternative strategies against. Lygus rugulipennis, the European tarnished plant bug, is a very polyphagous insect able to feed on more than 400 plant species. It is highly mobile and usually presents at high population densities. It is an