Molecular approaches based on PCR to identify and quantify arthropod internal feeders in grain

Abstract: Insect occur at each step along the chain of food production, leading to serious quantitative and qualitative losses and representing a major threat to food industries. Albeit several methodologies to detect stored pests have been developed, they present several drawbacks. Along the last decades, there has been a global trend in biological studies to use molecular approaches for diagnosis analysis. Although food industries have been using Polymerase Chain Reaction (PCR) diagnostics for food control it has not been used yet to detect insect infestations. We present different molecular approaches based on PCR methodologies to detect, identify and quantify the presence of insects in raw materials and processed food. Conventional PCR has been used for the detection of all Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) developmental stages in brown rice, wheat and maize even hidden inside the grain kernels. Multiplex PCR is a variant of conventional PCR permitting simultaneous detection of different target species. We have developed this method for the detection and discrimination of the three morphologically similar species of the genus Sitophilus [S. granarius (L.), S. oryzae (L.), S. zeamais (Motschulsky)] potentially present in stored grain facilities. On the other hand, decreasing amounts of R. dominica DNA in brown rice have been analysed by real-time PCR to be used for the quantification of this insect species in food. The introduction of these molecular approaches in stored grain and food industries will be very useful for the diagnosis of insect pest species, particularly to reveal infestations of insect immature stages hidden inside the grain.