The study was conducted during 2013–2015. It was established that the water lily aphid Rhopalosiphum nymphaeae was not commonly found on fruit trees in the country. Due to its specific bio-ecological characteristics the aphid was spread at a low density in some areas of Central and Eastern Bulgaria. The species infested mainly the tops of plum shoots and accidentally attacked shoots of peach trees. Colonies developed from April to early June, with a maximum in early May. The development was relatively fast – newborn larvae turned into adult females in 4–5 days to a week. Under lab conditions the species showed preference to temperatures between 25–300C and higher relative humidity. Under these conditions, the average fecundity of a female varied between 35 and 40 larvae. The colonies remained medium-sized, but caused significant delay in the growth of the infested shoots which makes the species a potentionally dangerous pest for young plum orchards and in nurseries.
Distribution, population dynamics and damage of water lily aphid Rhopalosiphum Nymphaeae Linnaeus (Hemiptera: Aphididae) on fruit trees in Bulgaria