Biotypes of insect pests of agricultural crops

Biotypes refer to the infraspecific category of insect populations with similar genotypes for biological attributes. They have been encountered mostly in association with cultivation of resistant crop cultivars and in well-studied cases a gene-for-gene relationship between pest virulence and host plant resistance has been documented. To date, biotypes have been reported to occur in 36 crop pest species belonging to 17 arthropod families in six Orders. Almost 50% of these pest species with known biotypes are aphids. Knowledge of occurrence of insect biotypes is crucial to the success of crop improvement programmes aiming to incorporate pest resistance. Biotypes represent evolutionary transients in the process of speciation and develop through natural selection acting upon genetic variations within the pest populations. To slow down the process of biotype selection, crop cultivars with broad genetic bases are needed.