Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.15

MOLECULAR CHARACTERIZATION OF TWO cDNAs CODING FOR ACETYLCHOLINESTARESE FROM THE PEACH POTATO APHID MYZUS PERSICAE

S. CASSANELLI*, B. CERCHIARI*, S. GIANNIN*, D. BIZZARO**, G.C. MANICARDI*

*) Dipartimento Interdisciplinare di Scienze Agrarie, Università di Modena e Reggio Emilia, Reggio Emilia

**) Istituto di Biologia e Genetica, Università Politecnica delle Marche, Ancona

acetylcholinesterase genes, aphid, Myzus persicae, pesticide resistance

Insecticide resistance is the major obstacle to control of agriculturally important pests. This worldwide problem has been documented for over 500 arthropod species, particularly among insects and mites. Resistance results in increased pesticide application frequencies, increased dosages, decreased yields and environmental damage. Given the tremendous difficulty and investment associated with development of new, safe and cost-effective insecticides, there is a grave need to preserve the efficacy of current and future insecticides. For these reasons, it is essentially to understand the mechanisms by which insects and mites acquire resistance so that we can intelligently design strategies to delay its onset.

Among pest crop insects, the peach potato aphid Myzus persicae is without any doubts one of the more representative species and one of the more serious pest on a wide range of agricultural and horticultural crops, in which it can cause substantial direct feeding and cosmetic damage as well as transmitting more than 100 virus diseases (Cravedi and Cervato 1991; Barbagallo et al., 1996; Bianco and De Luca, 1997).

Acetylcholinesterase (AChE) is the target site for two important classes of insecticides, organophosphates (OPs) and carbamates. Widespread use of these compounds has led to the development of resistance in many insect species, often due to an insensitive form of the enzyme. A modified acetylcholinesterase (MACE) that confers specific insensitivity to pirimicarb and triazamate has been previously reported in Myzus persicae (Moores et al., 1994; Foster and Devonshire, 1999). In order to determine the genetic basis of this insensitivity, we have amplified the AChE gene from both sensitive and insensitive italian populations of M. persicae using RT-PCR. However, no mutations were identified which could account for this insensitivity. The identification of a second AChE gene in the aphid species Schizaphis graminum (Gao et al., 2002) has led us to design a second couple of primers which led to the amplification of a sequence that differed from M. persicae AChE1 gene. However, no mutational changes were identified between sensitive and insensitive M. persicae populations also regarding this second AChE gene. Southern blotting and multiplex-PCR experiments demonstrate that both genes are present in a single copy and they are not differentially expressed between sensitive and insensitive populations.

The above mentioned data clearly demonstrate that the molecular basis of AChE resistance in italian population of M. persicae remain largely unknown.

References:

Barbagallo S, Cravedi P, Pasqualini E, Patti I, 1996 . Bayer S.p.A. Milano Divisione Agraria. 123 pp.

Bianco M, De Luca M, 1997 . Terra e vita, supplemento al n° 12: 4-6.

Cravedi P, Cervato P, 1991 . Informatore fitopatologico, 64:32-34.

Foster SP, Devonshire AL, 1999 - Pestic. Sci., 55: 810-814.

Gao JR, Kambhampati S, Zhu Y, 2002. Insect Biochem Mol Biol 32: 765-775.

Moores GD, Devine GJ, Devonshire AL, 1994 - Pesticide Biochem. Physiol., 49: 114-120.