Our Ijyini^ Resources — Hawaii 



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biological-conlrol introductions in the demise 

 of tiiese native bugs. Recent observations sug- 

 gest that small populations of the koa bug still 

 survive on most of the major islands, but quan- 

 titative status surveys and protection for this 

 insect may need to be initiated to ensure its con- 

 tinued existence. 



These examples suppoil the arguments of 

 Gagne and Howarth (1985) and Howarth ( 1991 ) 

 that alien parasitoids are the major factor con- 

 tributing to the decline and extinction of many 

 native insect species. Lepidopteran caterpillars 

 were an important food source for native forest 

 birds and other native organisms; thus, their 

 decline may affect other parts of the forest com- 

 munity. The ability of non-native arthropods to 

 invade intact native communities demonstrates 

 that conservation efforts aimed at habitat 

 preservation, or the selection and management 

 of nature reserves based on plant diversity or 

 endemism. may not provide sufficient protec- 

 tion for some insects and their associated biota 

 because of the continued emphasis on biologi- 

 cal control and insufficient quarantine control in 

 Hawaii. The effect of invasive alien arthropods 

 means that we could save the forest and still 

 lose the bugs, but we would eventually lose the 

 forest as well because of the loss of pollinators 

 and other functional groups of insects. 



Extinctions 



With at least 30% of Hawaii's native birds 

 (Stone 1989) and mollusks (Solem 1990) 

 extinct, it is likely that Hawaii has also lost a 

 significant proportion of its terrestrial arthropod 

 fauna. While 36 arthropod species are recog- 

 nized as extinct by the U.S. Fish and Wildlife 

 Service, populations of two species, a damseltly 

 (Megalagrion nesioles) and a sphinx moth 

 (Maudiica hiackhunil). have recently been 

 redi.scovered. The lack of intensive surveys for 

 most of Hawaii's rare arthropods makes their 

 status equivocal and weakens arguments for the 

 allocation of conservation resources for these 

 animals. 



One of the few areas in Hawaii where 

 arthropod extinctions are reasonably well docu- 

 mented is on Laysan Island in the northwestern 

 part of the chain. While only 3.8 km^ (1.5 mi-) 

 in size, it harbored at one time a native arthro- 

 pod fauna of at least 77 taxa with at least 14 

 endemic species (Conant et al. 1984). With 

 intensive surveys during the 1960's and 1980's, 

 we now know that 35% of Laysan's endemic 

 species are extinct. Other evidence of arthropod 

 extinctions comes from those species associated 

 with endangered or extinct plants. In 1917 a 

 new species of Proterhimis weevil was collect- 

 ed from the last remaining tree of 

 Hibiscadclplms giffardiamis on the island of 



Hawaii. While the tree has been given a reprieve 

 from extinction by propagation of individuals 

 from seed, the weevil, which breeds in dying 

 branches, was doomed with the death of the last 

 wild tree. Many Hawaiian insect groups are 

 similarly extremely host-specific; for example, 

 some species of long-horned beetles 

 {PUigitliniy.siis), with 139 known species, and 

 leaf bugs (Nesiomiris), with 50 species, occur 

 on rare hosts and face a similar fate. 



Survey Needs 



Waiting for confirmations of extinctions or 

 the di.scoveries of relict populations is inetfec- 

 tive. reactive conservation and will not preserve 

 Hawaii's remaining ailhropods. We need to 

 identify species early in their decline or at least 

 before they slide beyond recovery (Howarth and 

 Ramsay 1991). This report is limited to the 

 insects, but other native invertebrates deserve 

 mention, including the spiders and relatives 

 (arachnids), sandhoppers and relatives (crus- 

 taceans) (Howarth and Mull 1992; Nishida 

 1992). and mollusks (Solem 1990; Cowie et al.. 

 in press). The worms and smaller invertebrate 

 groups are even less well-known than the 

 arthropods. 



The urgency and effectiveness of status sur- 

 veys are exemplified by one being conducted 

 for Hawaii's damselflies. On the island of Oahu 

 alone, two damseltly species are believed 

 extinct, and three additional taxa are severely 

 reduced from their historical ranges and in dan- 

 ger of extinction. For example, sometime 

 between 1983 and 1985. Megalagrion nigro- 

 luunatiim mgwlineatitm disappeared from its 

 usual haunts along streams near Honolulu. 

 Surveys begun in 1990 have found it in only 

 three isolated localities near the headwaters of 

 Oahu streams. This represents a greater than 

 99% reduction in range in a decade. Most of its 

 former habitat still appears suitable and the rea- 

 sons for its decline are uncertain, but 

 researchers suspect the decline results from the 

 effects of non-native species, as well as habitat 

 destruction (Polhemus 1993). 



Status surveys of additional selected groups 

 of arthropods should be a top priority so that 

 appropriate conservation measures can be 

 planned. Studies on the systematics of 

 Hawaiian biota, including descriptions of new 

 species, are also urgently needed. Whether a 

 population represents a native or non-native 

 species or 1, 10, or 20 closely related species 

 has bearing on effective conservation strategies 

 in reserves (Howaith and Ramsay 1991). 



References 



Asquilh. A., and R.H. Messing. 1993. Contemporaiy 

 Hawaiian insect fauna of a lowland agricultural area on 



The koa bug ( Ctileotuiuis l^lack- 

 Imnnae). the largest Hawaiian true 

 bug (three-fourths inch long), was 

 common, but few have been seen 

 since 197S. 



