Aphid population fluctuations and patterns of species dominance in Puerto Rico

Papaya ringspot virus (PRSV) is a non-persistently transmitted virus affecting papaya and cucurbit production worldwide. Papaya is not known to be colonized by any species of aphid, but multiple species can transmit the virus. That means that transmission depends on aphid population fluctuations and the immigration of aphid alates into papaya orchards. Identifying seasonal patterns to aphid population fluctuations and identifying the species making up these populations will allow growers to avoid planting when aphid populations are high and the risk of infection is also high, as well as identify specific behaviors that may be exploited to keep aphid vectors out of papaya orchards. Yellow sticky cards revealed regular fluctuations of alate aphid populations, with peaks in the summer months, but high numbers also in the winter. Yellow pan traps were used to trap aphids each month in subsequent years to identify the species composition of these population peaks. Ninety percent of the aphids trapped at three different sites were Aphis spiraecola. Our data indicate that there is not an ideal time for planting papaya to avoid infection by PRSV, but that the bulk of immigrating aphids are composed of one species.