Final Comprehensive Conservation Plan - U.S. Fish and Wildlife ...

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
wasps are widely established throughout the unit, except between 3,500-5,453 ft. The relative
abundances of western yellowjacket wasps varied over time, with peaks during autumn (September-
December) at the lower elevations and peaks during winter (August- February) at the upper reaches.
These seasonal fluctuations are typical of western yellowjacket wasp populations observed in other
mesic forests (Haines and Foote 2005).
Western yellowjacket wasp populations can be reduced by directly applying a pesticide to an active
nest or by using a combination of bait (e.g., canned tuna cat food) and chemical toxicant (0.5 percent
microencapsulated diazinon). This was found to be particularly effective in controlling populations
(Nishida and Evenhuis 2000).
Two-spotted Leafhoppers (Sophonia rufofascia)
The two-spotted leafhopper has been implicated in the dieback of uluhe and „ōhi„a (Haines and Foote
2005). The leafhopper is present on the KFU, especially between elevations of 1,900-4,500 ft. Within
the lower reaches, additional concentrations occur specifically at about 2,297-3,117 ft.
Rainfall, temperature, and vegetation differences may play a role in these distributional trends
(Haines and Foote 2005). Currently, a management strategy has not been developed to control the
two-spotted leafhopper.
Ants
More than 40 nonnative ant species have colonized Hawai„i (Hawaii Ant Group 2007). Ants have
been labeled as the “the greatest arthropod threat to conservation in the Pacific” (Nishida and
Evenhuis 2000) due to their impact to native flora and fauna. Ants are plant predators that harvest
seeds, prune foliage, and directly compete with native invertebrates and vertebrate species, creating
favorable conditions for other invasive biota (Nishida and Evenhuis 2000).
Four ant species were collected from the KFU: Cardiocondyla wroughtoni, Paratrechina
bourbonica, Solenopsis papuana, and Tetramorium bicarinatum. Ant abundances were measured at
the KFU using protein bait (canned cat food) and carbohydrate bait (guava jam). Two of these
species (P. bourbonica and S. papuana) were found in high numbers at KFU (Haines and Foote
2005). Occurring between 1,900-3,050 ft, these species were observed only in the lower reaches of
KFU. Only a few specimens of the two additional ant species (C. wroughtoni and T. bicarinatum)
were noted (Haines and Foote 2005).
Ant control is difficult in dense forests, and current control methods have proved ineffective. The use
of baits with pesticides helps to control population, but entail aerial application of a bait product.
This technique is not permitted in Hawai„i (Haines and Foote 2005).
4.12.6 Introduced Plants
Invasive species are recognized as a major threat to native ecosystems and to the survival of
threatened and endangered species (Pimental 2005). At the ecosystem level, invasive plants have
been shown to be capable of changing fire regimes (D‟Antonio and Vitosek 1992), altering nutrient
cycling patterns (Vitousek 1990), and modifying the surface runoff of water (Vitousek 1992).
4-96 Chapter 4. Refuge Biology and Habitats