Population Dynamics of Green Peach Aphid, Myzus persicae (Sulzer) on Sweetpotato Weevil, Cylas formicarius (Fabricius), Infested or Noninfested Sweetpotato Plants

Sweetpotato weevil (SPW), Cylas formicarius (Fabricius), is the most damaging root-feeding insect on sweetpotato. Larval feeding within storage roots reduces yield and induces terpene production, rendering roots inedible. In Louisiana, sweetpotato is frequently infected with potyviruses which are transmitted by green peach aphid (GPA), Myzus persicae (Sulzer). Little is known on how these phytophagous insects interact and how a colonizing plant virus vector will respond to SPW root infestation. In order to address this knowledge gap, GPA population dynamics were studied on sweetpotato plants grown from either SPW-infested or uninfested storage roots under greenhouse conditions. Single green peach aphid adult apterae were placed on individual leaf cores in growth chambers held at 25±0.2°C, 50±5% RH and a photoperiod of 14:10 (L:D). Adults were allowed to larviposit and then were removed. Life tables were constructed and intrinsic rates of increase (r_m) were calculated. SPW infested plants had lower r_m, decreased longevity, and reduced net reproductive rate compared to uninfested plants. Thus, GPA fitness was negatively influenced by SPW infestation. This study indicates that below-ground herbivory can influence above-ground insect infestations and may be influencing virus vector epidemiology.