Diet analysis of small mammal pests: A comparison of molecular and microhistological methods

Knowledge of what pest species are eating is important to determine their impact on stored food products and to plan management strategies accordingly. In this study, we investigated the food habits of 2 rodents, Rattus rattus (ship rat) and Mus musculus castaneus (house mouse) as well as an insectivore, Suncus murinus (shrew), present in human dwellings. Both a microhistological approach and a DNA barcoding approach were used in the present study. Following DNA extraction, amplification was performed using group-specific primers targeting birds, plants and invertebrates. Resulting polymerase chain reaction products were sequenced and analyzed to identify the different prey species present in the gut contents. The findings from the application of both techniques were in agreement, but the detection of prey type with each technique was different. The DNA barcoding approach gave greater species-level identification when compared to the microhistological method, especially for the invertebrate and avian prey. Overall, with both techniques, 23 prey taxa were identified in the gut contents of the 3 species, including 15 plants, 7 insects and a single bird species. We conclude that with a selection of suitable "barcode genes" and optimization of polymerase chain reaction protocols, DNA barcoding can provide more accurate and faster results. Prey detection from either technique alone can bias the dietary information. Hence, combining prey information of both microhistological analysis and DNA barcoding is recommended to study pest diet, especially if the pest is an omnivore or insectivore species.