Earlier this year, the Invasive Species Management Team kicked off the spring with the installation of several southern pine beetle (SPB) traps at Minnewaska State Park Preserve and a few other locations. Southern pine beetle, Dendroctonus frontalis, is a 2-4mm long bark beetle, reddish brown to black in color, that hails from the southeastern United States and attacks pine trees. The female will locate a host tree, most commonly one with a compromised defense system as noted by the presence of alpha-pinene, a chemical released by stressed trees. The females then release the pheromone frontalin to attract males for mating, as well as other males and females. Males also secrete a pheromone, endo-brevicomin, summoning more beetles to congregate. The beetles enter the trees through cracks in the bark. In an effort to eject the beetle, pine trees will produce resin to push them out. The resulting little, lumpy sap nuggets are called pitch tubes and are a good indicator of SPB infestation. Once in the tree, SPB starts constructing curved tubes, or galleries, in the cambium to lay their eggs in. It is in the cambium that we find the xylem and phloem tissue, which transports water and nutrients through the tree and therefore helping the tree growth. Larvae move to the inner bark immediately after hatching, and then to the outer bark to feed as they mature. When they become adults, they chew round exit holes in a “shotgun” pattern, large enough only to fit a pencil tip. The exit holes are another sign of infestation to be on the lookout for. The chewing of galleries disrupts the flow of water and nutrients, resulting in the needles fading and ultimately tree death in as little as 2-4 months. The Long Island Central Pine Barrens have been particularly damaged by SPB. This may be due in part to the lack of fire as a management technique to thin stands, reducing competition and therefore resulting in healthier trees. Additionally, smoke from fires overpowers the beetle’s pheromonal communication, thus impeding their spread.
Because of how widespread SPB distribution has become, eradication of the species is simply not possible. The main method employed to suppress invasions is the cutting and removal of infested trees. A more proactive method includes monitoring pines for the early infestations of SPB to enable a rapid response to the arrival of SPB; bringing us back to Minnewaska State Park Preserve. The Sam’s Point area of Minnewaska is home to the only dwarf pine ridges ecosystem in the world, making it a globally unique and rare site. Therefore, monitoring for the arrival of SPB is imperative for the preservation of this rare pitch pine barrens as well as more common pitch pine communities of Minnewaska.
Entomologist Tom Schmeelk with the Department of Environmental Conservation (DEC) came to Minnewaska to hoist the traps and explain how they work. The traps used are Lindgren funnel traps, with a chain of funnels that mimics a tree stem. Several lures, or packets of pheromoneswere placed inside the trap which is then hung in a hardwood tree several feet off the ground and from the trunk. The lures utilized are frontalin, the sex pheromone secreted by females, and endo-brevicomin, the aggregation pheromone secreted by males. In addition, alpha-pinene was attached, a host volatile produced by stressed trees. The beetles are lured to the trap and funneled into a collection cup, the contents of which are sent to DEC to be checked for the presence of SPB.
For those concerned that the traps will attract beetles into the park that otherwise would’ve remained absent, rest assured that these are short-range traps that would only lure beetles within a few mile radius- meaning they only attract beetles already in the area. Being unaware of their presence in the park would be the much bigger risk to the park’s pine dominated ecosystems and all the species that depend on these, including the rare dwarf pines. Last year all the traps remained empty, let’s hope for the same this year!
Post by Sarantia Mitsinikos, Invasive Species Project Steward with SCA/Americorps/State Parks
Featured image: southern pine beetle, Steven Valley, Oregon Department of Agriculture, Bugwood.org