Demographic Statistics for the Pea Aphid (Homoptera: Aphididae) on Resistant and Susceptible Red Clovers

Abstract

Life tables were constructed for pea aphid, Acyrthosiphon pisum (Harris), developing on red clover, Trifolium pretense L., in growth chambers. Demographic statistics for pea aphids on three red clovers-N-2 germplasm (pea aphid resistant), ‘Redland’ (susceptibility level unknown), and ‘Tensas’ (pea aphid susceptible)-were computed to study the influence of resistance in red clover on aphid population dynamics. Resistance in N-2 red clover causes a significantly lower instantaneous rate of increase ( r ) for the pea aphid compared with ‘Tensas’ and ‘Redland’. Net reproductive rate per generation ( R o) was significantly higher on ‘Tensas’ than on N-2. Age-specific survivorship ( l x) was significantly higher on ‘Tensas’ and ‘Redland’ than on N-2 with 16-d-old adults. Development time for the first instar was significantly longer on N-2 than on ‘Redland’ and ‘Tensas’. However, mean generation time ( T ) of the pea aphid did not differ among the three red clovers. N-2 exhibited resistance to pea aphid, which reduced aphid population growth potential. Demographic statistics are useful tools to explore the effects or influences of host plant resistance on present and future populations of a pest.