Life history information on Allokermes rattani, the kermes scale associated with drippy blight disease of red oaks
Wednesday, November 18, 2015
Exhibit Hall BC (Convention Center)
Drippy blight is a recently recognized condition that seriously affects several kinds of red oak (e.g., Quercus rubra, Q. palustris
). This condition appears to be caused by the combined activity of two organisms, a kermes scale insect (Allokermes rattani
) and the bacterium Lonsdalea quercina
(Snelling et al 2011; Ibarra Caballero et al 2014). Symptoms on Northern red oak and pin oak include stunted growth, witches’ brooms, and branch dieback; in severe cases it contributes to entire tree decline, perhaps accelerated by effects of secondary organisms such as the flatheaded appletree borer (Chrysobothris femorata
). Furthermore, the massive oozing of bacteria from infected branches creates sticky film on leaves and surfaces on which it drops.
Kermes scales are an understudied yet economically important group of insects. Of the resources on the insect family Kermesidae, only a few sources mention Allokermes rattani. The life history information available on A. rattani is limited to a description of post-reproductive females. Our initial life history study has documented when nymphs are mobile, the immature overwintering locations, and the placement of settled adult females on the oak branches. We are working toward a complete study to describe this insect’s life history and substantially increase our knowledge of this disease complex.