Task 6 Extension
Principal Investigator(s): Mark Muegge
We mutually agree for Mark Muegge to deliver the following during the period of June 1, 2006 to May 31, 2007, using funds from the Rio Grande Basin Initiative:
- Establish field populations of the introduced leaf beetle, Diorhabda elongata, for biological control of saltcedar at specific locations along the Pecos River ecosystem in Texas.
- Once established, re-distribute the beetles from these sites to local landowners and land managers.
- In our efforts to accomplish goal 1, secondary objectives will be to determine the most effective and efficient procedure for establishing populations of this beetle in the field and determine their rate of movement.
- It may take two years of building the populations in the field cage and releasing in sleeve cages before a local field population is established. Once beetles successfully overwinter in the field and increase during the following summer, maintaining a field cage population should not be necessary.
- January-February. Locate cage sites, set up large (10’x10’x7’) field cages and cut back saltcedar tree to be enclosed by cage and at least 10 saltcedar trees adjacent to the cage. Place cattle guards around cages to protect from foraging cattle and wildlife.
- April-May: Field Cage. Place 50 beetles into each cage. Prior to release, search the tree and destroy all predatory arthropods that may feed on the beetles. Record the height and cross section of the trees canopy and note condition of foliage (green, yellow, dead) and presence of leafhoppers.
- May-June: Field Cage. Inspect cages once a week and record the number of adult beetles, beetle egg masses and larvae observed on the tree by visual search. Also record number of ants seen on the tree and kill all predatory arthropods in the cage. Record conditions of tree foliage and degree of defoliation by beetles. Record rainfall each week.
- June: Field Cage. If beetle populations have increased sufficiently, beetles will be collected and put into sleeve cages as described below.
- June, July and August, every two weeks: Both the Cage Site and Open Field Release Site. Once the first generation of beetles is complete in the sleeve cage study, weekly inspection is no longer necessary. The goal now is to determine if beetles are surviving outside on the GZ tree and adjacent cut back trees. Conduct a visual search of the GZ tree and adjacent cut-back trees for 5 minutes per tree, and record the number of adults and larvae present and percent tree defoliation by beetles.
- August-September: Every two weeks. Examine the tree inside the large field cage for re-growth. If sufficient re-growth has occurred release about 50 beetles into the cage to establish an overwintering population. Once beetles are released inside the cage, inspect the cage once every two weeks and record the number of adult beetles, beetle egg masses and larvae observed on the tree by visual search. Also record number of ants seen on the tree and kill all predatory arthropods in the cage. Record conditions of tree foliage and degree of defoliation by beetles. Rate number of leafhoppers as low (less than 50 per cage), moderate (50-500) or high (more than 500 per cage).
- October-March: Once a Month. Visit each cage site and maintain cattle panels, repair cage as needed and record rainfall. Record if cage area is flooded or other important factors. In January or February, cut back tree in cage and the 10 trees outside the cage at both the cage and Open Field release sites. Beetles should appear in cage once saltcedar begins to break bud in early April.