287 JUNE 1990 Nsw ZnnLeNoMosQUITo SunvnY

NEW ZEALAND'S NORTHERN SURVEY, 1988-891

MARSHALL LAIRD,

"Awawhare," Pahi Road,RD #1, Paparoa,New Zealan'd

ABSTRACT. The latest mosquito survey of the warmer regions of Nerp Zealand (NZ) sampled 2'304 Iarval mosquito habitats of all major categ"ories.While revealing_noevidence of new establishmentsof produced revealing the underu,ilization of types of habitats that "l"ti. -".i"iioes, ii important"data ''greenhouse "o"iJU" i""ua"d now or in the future (especiallyifthe effect" eventually causeseven quite small rises in averagetemperatures and sealevels). Although Iong feared additions of malaria vectors to u fur.ru still lacking"anyspecies ofAn opheles,or of essentiallytropical arbovirusvectors from neighboring ;;;;i". a" the n6rth and northeasti may not materialize failing climatic amelioration, a new danger upp""t"d at the beginning of the 1988-89Northern Mosquito Surviy whel A ed'esalbopictus was. reported for the nrst time fiom Fijii. This vector of denguehemorihagic fever and Ross River virus has since been .pi""Ji.g *iaay on the Lrchipelago's main iJland, Viti Levu, whence much air and sea traffic reaches iiZ. i"foi-ution presentedani diicussed herein strongly supports the continuance and improvement of international aircraft disinsection and other quarantine measures.

INTRODUCTION in colonizing NZ, where there are North Island east coast and northern South Island port foci On the basisof his 1918-19North Auckland (Belkin a dispersalpattern fullv 1968)-exhibits "It mosquito survey, Miller (1920) reported 2 of supportingthe statement (Lee et al. 1982): New Zealand's(NZ's) 3 exotic speciesbelieved s"u*s .eu.ottable to assumethat Ae. notoscrip- to have been established since the European tus has been introduced to New Zealand." rediscovery.These were Culex quinquefoscintus New Zealand'sthird and latest presumed ex- Say [isted as Taeniorhynchusacer (Walker) see otic is Ae. australis(Erichson). Its synonomyis Lee et al. (1989)1, and Aedes notosviptus fully discussedby Lee et al. (1984),who accept (Skuse)[reported as a memberof subgenusOch- its (Belkin 1962)subgeneric designation as one lerotatus-see Lee et al. (1982)1.The latter, of 2 otherwise uniquely Australian members of actually a Finlnya, is otherwise found from In- the subgenusHalaedes. Only known from south- donesiathrough Papua New Guinea to Australia ernmostprovinces of the SouthIsland and Stew- and the New Caledonian area. A Category 8 art Island (Nye 1962,Nye and McGregor 1964, Iarval habitat3 utilizer in nature, it readily dis- Belkin 1968),this brackish water, rock pool- perses to Category 9 sites, as do many other utilizer may well be a Tasmanian strain im- members of its subgenus(Horsfall 1955, Laird ported by timber vesselsto southern NZ ports 1988).This behavioraltrait renderedAe. noto- by the 1960s (Pillai and Ramalingam 1984)' scriptus as transportable aboard sailing vessels These authors disagreedwith Belkin's (1968) (and as the now virtually pantropical to a large soeculationabout a natural (windborne caniage extent pansubtropical, bearing in mind their oleggs) arrival from Australia, and I agreewith American dispersal) Cx. quinquefasciatus and them. In southern parts of the South Island, Ae. (Linn.). Aedesaegypti Despitethe view of Chris- australisoccupies Category 6 and 8 larval habi- tophers (1960) that the Iatter could establish tats of brackish splashpooland seepagetypes, just northward from south of Auckland City "similar to those occupiedby O. fusctts" (Belkin where the 10"C winter isotherm line coincides 1968).As yet, the former is unrecordedfrom the with the Bombay Hills, northern NZ may still North Island, and need not concern us further be a shadetoo cool for the latter species.Not- here. withstanding,Ae. notoscnptus-having proved Miller (1920)and Graham (1929,1939) rec- rather more successfulthan Cx. quinquefasciatus ognized the danger posed to NZ by possible introductions of Anophelesspp. to a temperate lacking malaria and its vectors. The country "Anophe- 1 This researchwas conductedfor the New Zealand latter author (1939) actually reported Department of Health, which has approvedand partly les maculipennisMeigen" from vesselsreaching supportedpublication. Auckland from Indonesia in May and Septem- 2 Honorary ResearchFellow, Department of Zool- ber 1929.As shownby Belkin (1962)and Lee et ogy, University of Auckland, Private Bag, Auckland, al. (1987b),this identification of a continental New Zealand. European/SW Asian/northern Siberian mos- 3 habitat classification herein fol- Larval mosquito wrong. Perhaps Graham Iows the rational l1-category system (Table 3) pro- quito must have been posed as an international standard by Laird (1988). was misled by one of the few sourcebooks that Some New Zealand.examples of these categoriesare would then have been available to him, i.e', illustratedin Figs.1-12. Tidswell (1910),which refersto An. maculipen-

Jounuu oF THEAuenrcnN Moseurro CoNrRor,Assocrlrrou Vor,.6, No. 2

Auckland,in the first weekof April, 1989.There Interestingly, all 3 of the aboveepibionts were and elsewhereunder similarly heavily polluted present on the cuticle ofthe largest-stageIarvae "Culicidae," circumstances,the sheathedbacterium, Sphaer- of one of Belkin's NZ Paradixa otilus natans Kutzing (see Laird 1959, 1988) neozelandica(Tonnoir), collectedfrom a highly added to the larval vestiture together with uni- polluted stream (Category1) in South Auckland dentified Cyanobacteriaand Fungi. (late November). The site was not far from the Mangere SewageTreatment Plant, from which Belkin (1968)reported both larvae and adults Table 1. Regional coverage of survey. in early March 1965.Almost 2 decadesearlier, immediate aftermath of World War II Region Samples in the and in my then capacity of Royal New Zealand Northland Area Health Board 853 Air Force Entomologist, I made an urgent flight South Auckland HDU 599 Wellington to Auckland to investigate a Hamilton HDU from 513 an who had served in the AucklandCentral HDU 183 report from airman TakapunaHDU 156 South Pacific forward zone. Having learnt to recognizeanopheline larvae on Guadalcanal, Total 2,304 Solomon Islands, and in Papua New Guinea, he had noticed what he took to be these in the surroundingsof NZ's then only international Table 2. Mosquito species identified. airport. Upon arrival, they turned out to be the surface-hauntingIarvae of P. neozelandica.The Species Coliections incident servesas a fine example of what would "community * Culexperuigilzns Bergroth 931 nowadaysbe termed participation" ** Aedesnotoscriptus (Skuse) 426 and good public relations in vector awareness ** Culex quinquefasciatusSay 156 * and control. Opifexfuscus Hutton 32 In view of the frequencyof associationofAe. * Culer asteliaeBelkin 2 notoscriptus with Cr. peruigilans and/ot Cx. * MaorigoeLdiaargyropus (Walker) 2 quinquefasciatus(Table 4), it is of interest that Total 1,549*** larvae of the first-mentioned speciesnever bore * Vorticella nor Epistylis.This might be supposed Indigenous. due to the fact that such associations were ** Exotic. *** mostly in the relatively clean water of Category This total exceeds the number of mosquito- although V. micros- positive larval habitats reported (1,333, Table 3) be- 9 Iarval habitats. However, cause many of the latter exhibited mixed-species in- toma and E. lacustris populations peak under festations (Table 4). polysaprobic and mesosaprobicconditions re-

Table 3. The 11 major categories of larval mosquito habitats, showing their utilization by Culicidae in the 1988-89 Northern Mosouito Survev. Number Number Total no. - Percentage larva- Percentage Categories samples positive positive negative negative Aboue-groundwaters 1. (Flowingstreams-Fig. 1) 85 32 38 53 62 2. (Pondedstreams-Fig. 2) r72 97 56 44 3. (Lake edges-Fig. 3) ri) 646 7 54 4. (Marshes-Fig. 4; and oa 47 48 50 52 swamps-Fig.5) 5. (Shallowpermanent ponds) 89 38 43 DI 6. (Shallowtemporary pools) lt4 75 66 39 34 7. (Intermittent ephemeralpud- 84 zl Dz 68 dles) 8. (Natural containers-Figs.6, 155 46 30 109 70 7) 9. (Artificial containers-Figs.8- r,493 963 65 530 35 10) Subterraneanwaters 10. (Natural) I I 100 0 11. (Artificial-Figs. 11, 12) 1 I 100 0

Totals 2,304 1,333 58 971 42 JUNE1990 Npw Zpnlnrp MosQutro SuRvnv 293

Table 4. Mixed species infestations of individual larval habitats (species listed in decreasing order of associations, read irom left to right; figures below each taxon show the number of sites involved in each association).

Aedes Culex Culex CuLex Maorigoeldia Total notoscriptus peruigilans quinquefasciatus asteliae fuscus drgyroptls assocratrons t42 t42 t42 a9 32 5 5 5 5 1 1 1 I 1 JO ; JO 1 1 I

Overall 181 183 I 277 totals

in an atypical Category- 2- slte spectively (Laird 1988), both can lgtgttF l?f peruigilans enrichment; and as Bick (1972) iponded stream) which was spring-fedin the less organic "Small states with respect to the former, "- io- immediate vicinity of severalnormal Opifexlar nies may occui under mesosaprobicconditions, val habitats at Mangonui, Northland. pathogens,with just solitary specimenseven being found in the oli- Turning to parasitesand conspicuousby their sosaprobiczone"'While as already mentioned 2 exceptions these were field experience i-.trt ou.. half of the double infestations encoun- absence.In the light of wide particularly sur- iered occuned in tires, most of which were so elsewherein the world, it was positioned as to be charged with rainwater ini- prising to find no trace of mermithid nematodes, of ii"Uy, .o-. other Category 9 larval habitats in micro-poridian Protista or Blastocladiidea large a sampleof which ae. notoscriptuswas associatedwith one the genusCoelomomyces, in so S' Pillai and his or both of the 2 species of Culex held foul material-the more so, as J. from water-for example, meat cans that still bore colleagueshave describedmicrosporidians in- traces of their original contents when thrown Maorigoeldia argyropus and the apparently in into open garbagedumps. One such can exhib- troduced Ae. australis,besides Coelomomyces Island. ited Cx. peruigilans larvae, all with a heavy ves- the latter and Op. fuscus,in the South the hem- titure of V. microstorno, together with many Ovoidal bodies plentiful throughout perfectly clean larval Ae. notoscriptus-.The latter ocoelof all Op. fuscuslate-instarlarvae collected Bay, east- specieswas similarly free from epibionts in a from a brackish rockpool in Te Karo 7, 1989, horse trough organically rich enough to have ern Coromandel Peninsula, on April of attracted Cx. quinquefasciatussimilarly heavily appearedat first sight to be resting sporangia ex- infested with V. mi.crostoma-Again, in a plastic a- ipecies of Coelomomyces.More detailed Pillai sug- bucket containing quite clean water, there was amination in collaboration with J. S' a scattering of Epistytis over the cuticle of Cr. gests that the organism is really a eugregarine protozoan. 'Ae.pe ruigilanslarvae in associationwith uninfested iotoscripifus, while a similar situation in- Finally, fungal hyphae and conidiophores-as and volving either E. lacustrisor V. mi'crostonlawas yet unidentified-were noted on the thorax habi- noted for a numberoftires. anal segmentof larvae from 2 Category t wereAe. notoscrip- Perhaps,just as most cladoceranssuffer far tats. The speciesconcerned November 21, lessfrom epibionts than do (due to the tus (Orua Bay, South Auckland, pervigilans,in former's hydrofuge qualities as opposedto the 1988-in water tank), and Cr. notoscripttts latter's hydrophilic ones?-Hutchinson, 1975), association with uninfected Ae. 5, 1988- similar physical phenomena may apply within (Point Chevalier,Auckland, December the Culicidae. Although the matter merits ex- in tire). perimental study, the environmental prefer- ences of Op. fuscttssuffice to account for the DISCUSSION general freedom of larvae of this speciesfrom Culicidae in ciliate epibionts. For while it proved free from Occurrence and preualcnce of 2 (long since) such infestation in 31 ofthe 32 sites from which northern NZ: The 4 native and tallied it was identified, these were as usual decidedly accidentally imported species recorded minor details brackish, a circumstance inimical to V. micros- with earlier findings, apart from latter could torna andE.lacustris, both of which were equally of distribution and incidence. The (e.g., rainfall scatteredover larvae of Opifex and those of Cr. reflect seasonalvariables summer JouRNer,oF THE AuenrclN Mosqurro CoNrnor, Assocra,rroN VoL.6,No.2

vs. drought) and survey coverage;the project farming districts. It has been aided in its disper- took place in rather a wet period offering opti- sal by the practice of piling many discardedtires mum larval habitat availability, but had it been (sometimesup to 100 or more) to weigh down conducted a year later a sustained summer the plasticcovers of rural ensilagepiles, to men- drought would have resulted in a substantiallv tion only one exampleof the diversity of Cate- reducedtotal of collections.And until recentlv. gory 9 larval habitats characteristic of today's I would have acceptedthe opinions of Belkin throwaway society. Via artificial containers Ae. (1968) and Pillai (1979a)on the comparative notoscriptus had already radiated into other rarity and low frequencyof Cx. quinquefasciatus, types of NZ larval habitats characteristic "largely of which accordingto the former author is those of its countriesof origin [i.e., such Cate- confined to coastal areas in the vicinity of the gory 8 sitesas tree holesand rock potholes(Lee largerports on North Island."This is indeedso. et al. 1982)1,long ago. Thus Graham (1929) but it was not until early April that attention to "especially "gully reported it from rock hollows, those the traps" of the stormwater drainage occurringin caves"(i.e., Category 10) as well as system of Parnell, Auckland City, revealed a from rot-holes in various speciesof native trees, great abundance of this speciesthere. As the the leaf axils of nikau palms and Astelia spp., barredcovers of thesesumps were raised one bv and exceptionallyeven from "drains, swamps one from the gutters, huge assemblagesof aduli and water-holes."In the present survey it was and larval Cx. quinquefasciatus,often in associ- commonlycollected from the leaf-basetanks of ation with Cx.peruigilans and occasionallywith neotropical Bromeliaceae (Fig. 7) grown as Ae. notoscriptuswere revealed beneath, amply greenhouseornamentals. An interesting North- accounting for many complaints of a serious land finding concernedWaipoua Forest, where biting problem from local residents.In the final a marginal zone investigatedin late March 1989 days of the survey, a similar situation was re- yielded several Category 9 sites ranging from a ,,gully "gully vealedin parts of South Auckland,where trap" at a camp mess hall, through steel traps" nearthe airport'sInternational Terminal drums, tires, bucketsand ubiquitousbeer cans at Mangere were sustaining large populations of and bottles, to many Category8 (natural con- both Cr. quinquefasciartusand Cx. peruigilans tainers) ones. The former group had opened and thereby furnishing sourcesof both to air- entry to the latter, in which Ae. notoscriptnswas craft departing for foreign destinations, and at identified from slits in prostrate logs and stand- the sametime serving as potential oviposition ing trees, as well as from Bush FIax. Astelia sites for pollution-tolerant foreign mosquitoes neruosa,leaf axils. In this center of concentra- shouldthese evade on-arrival disinsection. tion of an exotic peridomesticmosquito revert- Still on the matter of international arrival/ ing to its original natural larval sites,Ae. notos- departureplaces, other Cx.quinquefascialus col- criptus larvae were not only also found in a lections were made from a variety of Category9 Category 2 habitat (ponded stream), but in a sites on Auckland's container wharf and the streambackwater (Category 1), too. Devonport Naval Base. Positive sampleswere No intensive samplingof leaf axil, tree hole also taken on the nearby Hauraki Gulf islands and other Category 8 habitats was undertaken of Waihekeand Rakino.Further afield,Belkin's in denseforest. Had this beendone, there would (1968)first record of this speciesfrom the old certainly have been many more recordsof the port of Coromandelwas confirmed.New Coro- indigenous Cx. asteliae and Mg. argyropus;but mandel Peninsula locality recordswere obtained it was felt more important for the purposes of a little further north, at Koputauaki Bay, and the survey to concentrate on the surroundings from the old port city of Thames (in the latter of airports and seaportsand the rural hinterland casefrom a Category t habitat, backwaters of a that further mosquito arrivals would have to foul streamlet). Perhaps the most interesting traversebefore reachingmajor forests.Coastal new finding of Cx. quinquefasciatuswas the first areaswere searchedwherever feasible, though, inland one,from a schoolswimming pool in the and this resulted in findings of Op.ftncus whet- city of Hamilton, Waikato. The specieswas not ever suitable Iarval habitats existed. collected elsewherethere, and the finding could The only other mosquitoesknown to occur in easily have been due to road, rail or air trans- the northern parts ofAuckland Province but not portation from Auckland; in which connection, reported in the 1988-89 larval survey are: Ae. it is pertinent that an unusual Category9 larval antipodeus(Edwards), Coquillettidia tenuipalpis habitat, a pool on the metal floor of a railway (Edwards) and Cq. iracunda (Walker). Like wagonon an Auckland siding,yielded Cx. per- other membersof the tribe Mansoniini, Coquil- "rely uigilansand Ae. notoscriptus. Lettidiaspp. have larvaewhich on air within The last-mentioned exotic, now North Auck- the underwater roots of emergentplants and all land's second most plentiful and widespread have the siphon highly modified for piercing mosquito, has spread inland throughout the plant tissue" (Wood et al. 1979).Larvae of nei- 295 I JUNE 1990 Nrw Zser,eNoMosqurro SuRvev ther of the NZ speciesare known from the field, 20% and 427a, rcspectively.As 46% of aIl Cx. althoughaccording to Belkin (1968)1st instars quinquefasciatfussamples were mixed ones, too, were obtained from eggrafts by L' J. Dumbleton [h... figut.t are evidenceof the successof both (unpublished).Adults have been obtained from exoticsin competingfor availablelarval habitats Northland since the pioneer survey of Miller in the NZ environment' (1920:and seeBelkin 1968),there being a strong A generalunderutilization of potential larval association with marshlands rich in sedges, -o.quito sites in northern NZ has thus been reeds and other aquatic vegetation. Typical NZ turned to account by both exotic immigrants, Raupo (a bullrush, Typha orientalis) and Carex although distinctly more so by Ae. notoscriptus spp. are central to the aquatic complex within than 6y Cx. peruigilaias. The former, having *tiictr UottrNZ speciesof Coquillettidiomight be adaptedbettei to local conditions' has radiated expected to be found. So far, the manual up- into varied and widely dispersed larval niches rooting of much such vegetation, with care to (both near the likely ports of entry and deep region's most plentiful divertlhe underwater parts into a submerged inland) to become the "Ihis drum without breaking the water-film and so culicid after the indigenousCx. perui.gilans. largely dislodging larvae, has proved fruitless. highly adaptable specieswas obviously prior Aedbs antipodeusis a winter floodwater uti- frJe irom mosquito competition to the lizer, larvae of which were collected in 6 of arrival ofthe 2 foreignspecies. It has a remark- site Pillai's (19?94)July-September 1978 samples ably wide range of tolerancesin oviposition all 11 lar- from the vicinity of Whangarei. Although the selection,having been collected from of 6 of femalesare activeyear-round (Belkin 1968),the val habitat categories(positive examples 8-12), and timing of the present survey would have made which are illusfrated in Figs. 1-5, (Category8) it rather unlikely to come across immature dominatingin all but one of them stages,the more so as populationsof this,mem- in Table 5. only larval beiof the subgenusOchlerotatus seem charac- While natural containers were the subordinate teristicallysmall. habitats where Cr. peruigilans was C*. asteliae,a Factors releuant to possiblefuture establish- to other species,one ofthese was (1968) ments of mosquitoesin NZ: Offering a derivativJofthe former.Belkin suggested foreign "that popu- temperate climate and an adequate range of asteliaewas formed from a founder an isolated environments for Culicidae, NZ nevertheless lation of the peruigilans stock on still has an unusually limited mosquito fauna volcanic island where the only available fresh (14 species,only 11 of them indige-nous)for a water was in astelia axils" (probably those of the counfty of 269,063km' (103,886mi.'). It is thus Perching Lily, Collospermumhastatu,rL a con- pertinent to consider how this may affect the spicuousepiphyte on forest trees which is also a question of vulnerability to new introductions piott"er on bare volcanic rock). Such axils and of pestsand vectorsparalleling those of arthro- lorest tree holes are commonly negative for na- pods of agricultural and forestry importance tive mosquitoes,and although Ae. notoscriptus that continue to take place despite quarantine was quick to take advantageofthe circumstance measuresas expandingtrade and tourism break and was the speciesmost often collected from (397o) down former isolation. Category8 habitats-being present in 18 The proportion of 1988-89 collecting sites of the 46 found positive-the proportion of such actually positive for larval mosquitoes (58%; habitats that proved negative (70%; Table 3) Table 3) was appreciably Iess than has been was the highest for all categories. Originally found characteristicof NZ's nearerand warmer clearly a utilizer of surface and cave waters neighbors. Thus widespread surveys in many (percenlages tropical South Pacific island groupsand Queens- Table 5. Culex peruigilans occurrences in land, Australia (Laird 1956a), revealed that derived from overalllarva-positive habitat figures 3). overall, 372 (817o)of 457 actual and potential Table larval mosquito habitats sampled exhibited lar- Category Collection(s) % of occurrence L3l (3\Vo)-by comparisonwith vae.Moreover, 130 94 217 (16%) in the present project-harbored o09 95 (25%) more than one culicid species.Thus 85 3583 held2 species,33 (9%)3,9 (2%\4, 3 ([Vo\5 and 444 94 | (

(Categories1-7, 10), Cx. peruigilansmust have these are well-suited to keeping stock troughs begun to have accessto artificial containers in relatively or totally free from larvae (their effr- pre-European times. For the Moriori made cacy of coursebeing subject to the frequency of water containets, hahana, of wood and perhaps emptying for cleaning). There is presumptive of pumice also (Skinner 1923),and the Maori evidencehere that the phenomenaof notonectid manufactured both types while their beached flightlessnessand environmentally determined dugoutcanoes would have affordedsimilar larval polymorphism (Young 1970) might have some habitat prospects to mosquitoes as those of practical value in limiting mosquito populations many tropical Pacific islanders still do today. in theseclearly necessarywater bodies,besides Contraryto the experienceofBelkin (1968),but diminishingthe chancesof successfulestablish- in agreementwith that of Pillai (1979'), most ment by invadingexotics. (620,67Vo)of the present survey's931 collec- The best consequencesof such predation, tions of larval Cr. peruigilans were from Cate- however, would be offset by the prevalence of gory t habitats. The comparable figure for Ae. discardedtires (from which notonectids, dytis- notoscriptuswas 95%. cids and corixidswere never collected) near air- Of 37 different types of Category t habitats port and seaport likely reception areas and dominated by these 2 species,discarded tires throughout the urban and rural north. Until (613)and stock drinking troughs (210)were by now, NZ's greatest threat from a Category 9 far the most numerousand widespread.Both utilizer has beenassumed to be the cosmotrop- abound throughout rural areas;the former were ical or tropicopolitan (seeLee et aL, lg87a\ Ae. Iarva-positive at airports and seaports, and a aegypti.This specieswas establishedin eastern number of the latter yielded Cx. peruigilnns ad.- Australia (Skuse 1889)by December1882 ac- jacentto the perimetersof both AucklandInter- cordingto Lee et al. (1987a).By the early 1900s nationalAirport, Mangere,and Royal New Zea- (and possiblylong before)it was in Fiji (Theo- land Air Force Base,Auckland, at Whenuapai. bald 1903)and Samoa(Grunberg 1913). Perhaps Both are clearly dangerousas potential ovipo- Ae. aegypti is just a Iittle too tropical for NZ? sition sites for newly imported Culicidae, and After all, Cx. quinquefasciatushas achieved a neither proved anything like fully utilized. For greater latitudinal dispersion;yet it seemsfrom 190(31%) of the tires and 119(57%) of the stock data herein to be only just sufficiently tolerant drinking troughs altogether lacked Culicidae, a of NZ's temperate conditions to have main- fact that when addedto the multiple-occupancy tained itself (with a high summer population data presented earlier points to a prevailing peak) at and around the original ports of entry availability of oviposition sites awaiting Cate- in the warmer northern districts. Yet, Ae. ae- gory 9 larval habitat utilizers that might in gypti is still on the move, having only extended future be accidentally imported into NZ. its rangeto NZ's tropical neighborsof Tokelau Whether or not suchexotics havedirect sunlight and Niue as recently as the late 1960s,appar- tolerance is a factor here, for most water held ently in consequenceof importations during by tires is shadedby the rims (Fig. 8), while hurricane-reliefoperations (Piltai and Ramal- most gravity-filledstock troughs (Fig. 10) are in ingam 1984,Dale and Maddison 1984). open fields and unshaded.Now the tire/trough Latterly, though, the prime threat has occupancy rates exhibited by Cr. peruigilans, switchedto the Asian tiger mosquito, "wide a Stego- with its exceptionally toleranceof envi- myio second only to Ae. aegypti as a dengue ronmental conditions" (Belkin 1968),were 40 hemorrhagicfever virus vector and also able to and,34%,respectively, while thoseof Ae. notos- transmit Ross River virus. For although of SE criptus,which is as intolerant of direct sunlight Asian origin and until recent years regardedas in NZ (Graham 1929)as in all possiblesource a purely tropical species,this insect, following countries (Lee et al. 1982),were 41 and 47o, its 1985appearance in the United Statesvia the respectively. usedtire trade, has dispersedto far from tropical Another factor to be considered on the regionsof that country (Hawley 1988,Anony- chancesof successof future mosquitoinvasions mous 1989).This suggeststhat Ae. albopictus of NZ is predation. In that connection,field data (Skuse)might indeedbecome established in the sheetsfor 63 (53%) of the 119troughs negative warmer sector of NZ's North Island, once intro- for Culicidae mentioned that predators were duced. Having done so, and differing from Ae. common to abundant. Relevant samolesocca- aegyptiin its well-known although not exclusive sionally contained Corixidae,but thi dysticid (Laird and Mokry 1983)predilection for peri- beetle,Rhantus puluerosus, was more common, domesticCategory 9 larval sites,it wouldbe well and the backswimmer,Anisops ossimills, most placed for following such local paths as common of all. The last-mentionedwere fre- those already blazed by Ae. notoscriptusbackto quently flightless morphs. Being unable to the diversity of Category 8 larval habitats that from the habitat as winged notonectids can, it favors in nature in SE Asia (references in JUNE 1990 Npw Zpnr-ernMoseurro Sunvpr 297

Hawley 1988), thus becoming so deeply en- female Cx. annulirosfris was found a year later trenched in northern rural and forest country as in the passenger compartment of an aircraft to precludeeradication and render effective con- from Fiji (Laird 1952).World War II collections trol very difficult and extremely expensive.In from Whenuapai flights subsequently worked this connection,the writing on the wall was through were found to have twice included ex- furnished when tree hole colonization by Ae. amplesof Ae. uigilax from New Caledonia(Laird albopictuswas recognizedin the United States 1956b). (Foster1989). Since those days NZ has maintained efficient The aboveis no idle speculation.As the 1988- routine disinsection aboard arriving interna- 89 Northern Mosquito Survey was beginning, tional flights, and despite the enormous growth word was receivedof this mosquito's first intro- of aviation over the intervening period, no fur- duction into Fiji in the proximity of Nadi Inter- ther foreign mosquitoeshave become introduced national Airport (Fauran and Laille 1988).By into the northern regionsof Auckland, as earlier the secondhalfof 1989,the Asian tiger mosquito comprehensivesurveys and the presentone have had becomeentrenched around the main island shown. Meanwhile this area has acquired major of Viti Levu (J. S. Pillai, personalcommunica- tourist significance, compounding the problem tion, August21, 1989),from which shippingand in terms of ever-increasingnumbers of daily aviation maintain constant links with NZ. arrivals of loadedjumbo jets, and adding a new These links are far closer than those with the dimension to the likely consequencesof estab- previousnearest vicinity of Ae. albopictusto NZ, Iishmentsof suchspecies as thosenamed in the the Solomon and Santa Cruz islands, where it previousparagraph-that of a pest problem of had first beenrecognized in 1978(Elliott 1980), hitherto unexperienced dimensions, which perhaps as a result of a seaborneintroduction might prejudicetourism. One could be the estab- from Papua New Guinea. The speciesmust Iishment of Ae. uigilax, a brackish water utilizer therefore be regarded as posing an immediate thriving at the landward margin of mangrove threat to at leastAuckland Province. This threat swamps and in pools on associatedSalicornia includes a potential pest problem as well as a flats (Lee et al. 1984).Such Iarval habitats are possiblevector-borne arbovirus component.The characteristicof much of the Auckland area, same holds good for 2 other arbovirus vectors Northland and Coromandel Peninsula coasts resident in Fiji, Ae. uigilax (Skuse) and Cx. an- (all prime recreationalareas). Of the 97 Cate- nulirostrisSkuse, these being on epidemiological gory 4 habitats (marshesand swamps)sampled grounds the chief Australian vectors of Ross there, 20 were mangrove swamps (Auicennia River virus (Miles 1984). resinifera),of which L5 (75Vo)lacked any Culi- By 1954 the former mosquito was not yet cidae. Four of the others harbored Cx. peruigi- establishedin Fiji (Laird 1956a),although there lons, incidencebeing heavy only once. In the is believed to have been an apprehendedintro- remaining site, the samplebeing taken at a point ductionin 1940(R.J.A.W. Lever, in Paine1943). on the perimeter of Auckland International Air- It had arrived,though, by late 1957,perhaps via port where a culvert dischargeddrainage water Nadi International Airport (Burnett 1960).Both into the swamp, a few Cr. quinquefasciatuslar- speciesare also present elsewherein NZ's near vae were found. That site was within convenient vicinity, in New Caledoniaand eastern Aus- flight range of both international and domestic tralia. As in the case of Ae. albopictus, both terminals for parous mosquitoeschancing to would posepest problems as well as health ones, eludedisinsection measures. and thus could con- once establishedin northern NZ, where Cx. an- ceivably serve as a bridgehead, concentration nulirostris might be expectedto invade under- point and source of internal NZ dispersal for utilized categories 1-7 and 9 larval habitats. accidentally imported Ae. uigilax. Graham (1939) reported the discovery 10 years Carrying speculationa stagefurther, at a time earlier of larvae of the last-mentioned speciesin when possibleconsequences of the "greenhouse the hold of a ship reaching Auckland from Suva, effect" are the subject of much discussion and Fiji, and his later destruction of more larvae in controversy, it is worth noting that the 10'C a barrel on the nearby waterfront, while Laird winter isotherm line lies just south of Auckland (1951)detailed the finding of adult Cx. annuli- City. Christophers (1960) held that the area rosfrls in routine disinsection collections from 5 north of that Iine might be consideredsuitable aircrafb following arrival at RNZAF Station for Ae. aegypti. Whether or not this is so, the Whenuapai (then Auckland's only airport re- 1.5'C temperature rise over the next half cen- ceiving civilian as well as military airclaft from tury that is being forecast by advocatesof the abroad) from Fiji, Norfolk Island and Australia. above hypothesis would certainly enhance the In the last instance a female example was alive establishment opportunities for this species, when collected from a luggagebay of a plane others discussedherein and perhapssuch ma- from Sydney on April 20, 1950. Another Iive laria vectors as the Melanesian/northern Aus- 298 JouRNu oF THEArr,rpnrceN Moseurro CourRol AssoclnuoN Vor,.6, No. 2 tralian Anophelesfarauti Laveran. This might Belkin, J. N. 1962. The mosquitoesof the South occur if sea levels were raised significantly to Pacific.Univ. Calif. Press,Berkeley, 2 vols. (Diptera, influence the water table, thereby enlarging Belkin, J. N. 1968.Mosquito studies Culici- VIL The Culicidae of New Zealand. Contrib. and enhancingfloodwater availabil- dae). marshlands Am. Entomol.Inst. 3(1):1-182. ity in low-lying areas.The consequencesof the "greenhouse Bick, H. 19?2.Ciliated protozoa. An illustratedguide effect"would alsoenhance the pro- to the speciesused as biological indicators in fresh- duction of somemosquito species already pres- waterbiology. W. H. O., Geneva. ent, and the amelioratedclimate at the same Burnett, G. F. 1960.Filariasis research in Fiji 1957- time would encouragethe southward and inland 1959. A report to the Secretary of State to the spreadof Ae. notoscriptusand Cr. quinquefascia- Colonies,London. tus (Pillai and Laird 19895;Mogi 19906). Christophers,S. R. 1960.Aedes aegypti (L.), the yellow To conclude,source reduction-with particu- fevermosquito. Cambridge Univ. Press,England. P. S. and P. A. Maddison. 1984. Transport lar attention to off-rim tires-would be a wise Dale, servicesas an aid to insect dispersalin the South precaution and useful contribution to the limi- Pacific,pp. 225-256..In:M. Laird (ed.),Commerce tation ofpresentmosquito populations in north- and the spreadof pestsand diseasevectors, Praeger, ern NZ at this time. Both now and in the fore- New York. seeablefuture, though, as in the past, port in- Elliott, S. A. 1980.Aedes albopictus in the Solomon spections (above all with respect to arriving and Santa Cruz Islands,South Pacific. Trans. R. tires) and effective disinsection of aircraft Soc.Trop. Med. Hyg. 74:747-748. (Laird 1989) will comprise the essential first Fauran,P. and M. Laille. 1988.Surveillance entomo- defenseagainst economically and medically dan- logiquedes a6roportsinternationaux des Isles Fidji, pp. (1988),Inst. gerousmosquito importations into NZ. 283-286.In: Rapport Technique Pasteurde Noumea,Nouvelle-Cal6donie. Foster, B. E. 1989. Aedes albopictuslarvae collected ACKNOWLEDGMENTS from tree holesin southernIndiana. J. Am. Mosq. Control Assoc.5:95. Thanks are due to Mr. G. Martindale of the Graham, D. H. 1929. Mosquitoesof the Auckland Department of Health, Wellington, for exem- district. Trans. Proc.R. Soc.N. 2.60:205-244. plary liaison throughout my consultantship; to Graham,D. H. 1939.Mosquito life in the Auckland ProfessorE. C. Young of the Department of district. Trans. Proc.R. Soc.N. 2.69:210-244. Zoology,University of Auckland, for identifica- Grunberg,K. 1913.Zur Kenntnis der Culiciden-Fauna von Samoa.Entomol. Rundsch.30:130-131. tions of Heteroptera and advice concerning Cr. Hawley, W. A. 1988.The biology of Aedesalbopictu.s. quinquefascialiusincidence in suburban Auck- J. Am. Mosq. Control Assoc.4(Suppl. 1):1-40. land; to Messrs.D. A. Cummingand A. Parkes, Horsfall,W. R. 1955.Mosquitoes: their bionomicsand Hamilton HDU, for Figs 1, 3, 4,7,9, 10 and 2, relationto disease.Ronald Press, New York. 6 respectively;and to all other Health Protection Hutchinson,G. E. f975. A treatiseon limnology.Vol. Officers and trainees who were survey partici- III, Limnologicalbotany. John Wiley, New York. pants - not least to Mrs. D. J. Anderson of Laird, M. 1951. collected from aircraft arriving NAHB for her talentedpencil sketchesof larval in New Zealand.from abroad. Zool. Publ. Victoria habitats. I regret that it was not possibleto have Univ. Coll. Wellington 11, 1-30. 1952.Insects collected from aircraft arriving of her work included, as evidencethat Laird, M. had some in New Zealand,during 1951. J. Aviation Med. in biological illustration there's still room for 23:280-285. competitionwith the camera! Laird, M. 1956a.Studies of mosquitoesand freshwater ecologyin the SouthPacific. R. Soc.N. Z. Bull. 6:1- REFERNNCESCITED 2r3. 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