The dangers of diet and exercise: Movement and feeding interruption in the soybean aphid, Aphis glycines

Many species that feed on nutritionally poor foods must invest the vast majority of their time foraging and feeding. Such species may suffer from malnutrition if feeding is interrupted, either by predators, competitors, or abiotic conditions. Aphids are a prominent pest of many plants, damaging the plant through feeding on phloem and vectoring plant diseases. However, phloem is a poor source of amino acids, and aphids must spend large periods of time feeding to acquire sufficient nutrition for their growth and development. For this reason, interruptions of aphid feeding may have significant consequences for the aphid’s growth and reproductive success. Several recent reports and observations of the soybean aphid suggest that they are relatively mobile on their host plants. They walk to better feeding sites, avoid certain abiotic conditions, and walk away from predators and parasitoids that disturb their feeding. In this study, soybean aphid nymphs were experimentally disturbed, prevented from feeding for 30 minutes each day, and compared to control aphids that were left alone to determine the costs to fecundity, development rate, and survivorship to adulthood incurred by feeding interruptions. Preliminary data suggest that undisturbed soybean aphids mature faster than aphids that are disturbed or prevented from feeding for 30 minutes, while aphids that are prevented from feeding for 30 minutes per day produce fewer young and die sooner. This finding could suggest that disturbance by predators, migration to better feeding sites, or evading harsh environmental conditions could have significant sub-lethal effects.