Serological identification and quantification of potato cyst nematodes from clean cysts and processed soil samples

Two monoclonal antibodies which specifically recognise each of the two spec ies of potato cyst nematodes (PCN) and do not cross react with other specie s of soil nematodes, were used successfully in an immunoassay to identify a nd quantify PCN species using clean cysts and mixed populations. These anti bodies show reactivity only towards antigens prepared from live eggs and th ey recognise antigens which are easily released from the nematodes. The res ults presented in this paper show that serological identification and quant ification of PCN, not only from clean cysts but also from processed soil sa mples is achievable. A simple procedure to recover nematodes from soil samp les and then to release nematode antigens was devised. The use of these pro cedures and the immunoassay for quantification of PCN was validated in test s with soil samples from Northern Portugal. The flotation method proved to be as efficient as the Fenwick Can for cyst recovery from soil samples. A s ignificant correlation was obtained between results from immunoassay estima tes and the traditional method of cyst picking and egg counting. The amount of organic matter (OM) present in the soil samples affected the sensitivit y of the immunoassay but quantification of nematodes extracted from soil sa mples was possible with soils containing up to 14% of OM. The challenge rem ains to optimise the extraction procedures and the immunoassay, in practica l conditions with highly organic soils containing cysts of different sizes and ages.