ESA Annual Meetings Online Program
Flight response of the walnut twig beetle, Pityophthorus juglandis, to aggregation pheromones produced by low densities of males
Walnut twig beetles (WTB), Pityophthorus juglandis, are native to New Mexico, Arizona, California, and Mexico. Recent surveys have documented that WTB populations have spread to Tennessee (2010), Virginia (2011), and Pennsylvania (2011), states where eastern black walnut, Juglans nigra, is a major timber species. The impact of WTB on walnut has recently become accentuated by its association with a potent fungal pathogen, Geosmithia morbida. Eastern black walnut is particularly susceptible to G. morbida. WTB carry G. morbida spores and, during gallery construction, they deposit them in the phloem of branches and stems of walnut trees. These conidia germinate and the fungus colonizes the phloem. This weakens and can ultimately kill the tree. The disease condition (thousand cankers disease) has been known to kill a healthy tree in 1-3 years. Previous research has shown that male WTB colonize branches first, produce an aggregation pheromone, and the flight response of both sexes increases as the number of males in the branch is increased from 20 to 200. Using this framework, an experiment was designed to determine the minimum number of males necessary in an infested black walnut branch to attract conspecifics in a native stand of northern California black walnut, Juglans hindsii. This experiment ran from the end of April to mid-June of 2012. It appears that a threshold of 1 to 5 males is necessary to elicit a flight response of females and a threshold of 0 to 1 males is necessary to elicit a flight response of males. This response was measured relative to uninfested control branches or no-branch controls. There was a negligible flight response to the uninfested branches.
See more of: Student Poster Competition
