260 JouRul oF THEArrlpnrclN Mosquno CoNrRor,AssocrarroN Vor..7, No.2 PERSPECTIVESON MANAGEMENT OF PESTIFEROUS CHIRONOMIDAE (DIPTERA), AN EMERGING GLOBAL PROBLEM ARSHADALI Uniuersity of Florida, IFAS, Central Florida Researchand Education Center,2700 East CeleryAuenue. Sanford,FL 32771-9608 ABSTRACT. In recent years, adult Chironomidae emerging from some urban natural or man-made habllats have increasingly posed a variety of nuisance and economic problems, and in some situations medical problems to humans in different parts of the world. Although there are an estimated 4,000 or more speciesof chironomid midgesworldwide, lessthan 100species have been reported to be pesti'ferous. Among midge control methods, numerous laboratory and field studies have been conducted on the use of o^rqanochlorines,organophosphates (OPs), pyrethroids and insect growth regulators (IGRs). Field use of OP insecticides such as chlorpyrifos, temephos and others in the USA ind Japan hai generally resulted in larval control for 2-5 wk or longeiwith application rates below 0.56 kg AI/ha (U=S.q)ani 51-5 ppln (Japan).Frequent use of some OP insecticidesin the USA and Japan has caused.their increasedtolerance in severalmidge species.The IGRs, diflubenzuron and methoprene,provide alternate means for midge control. These IGRs in some situations suppressedadult midge eme.ge.tceby >g\Vo at rates (0.3 t<gll/_hqr A number ofparasites and pathogenshave been reported from mldgesin different parts of the woid'. Bacillus thuringiensis serovar. israelensisis effective igainst some mid-gespecies, but at rates at least 10x or higher established for mosquito larvicidal aciiuity. The flatriorm, Dugesia doro.tocephala,and some fish speciesoffer a goodpotential for midge control in somesituations. In l"arge habitatscovering hundreds or thousands of ha, information on t[e basic ecology of larval midges arid adult behavior is essential for formulating midge control criteria. More reseirch is neededln the biological and physical and cultural control of these pestiferousinsects. INTRODUCTION 1978), in the lagoon surrounding the city of Venice, Italy (AIi et al. 1985b),in man-made Nonbiting midge flies of the dipteran family urban and suburban aquatic environments, such Chironomidae commonly occur in most inland as shallow and open wastewater channels (Ali natural or man-made aquatic ecosystemsof di- and Mulla 1976a),water spreadingbasins (Ali verse natures. They inhabit shallow and fast and Mulla 1978a),sewage oxidation and settling flowing headwaters of streamsand rivers as well ponds and overflow gutters (Edwardset al. 1964, as deep and slow moving waters in lagoons. Spiller 1965,Tabaru1985b), and residential-rec- Midges occur in stagnant waters in small and reational lakes (Ali and Mulla 1977b,Ali et al. shallow temporary or permanent ditches and 1978). ponds and in large shallow or deep lakes. Chi- Generally, water bodies in urban and subur- ronomid larvae exhibit a very wide range of ban areasexposed to intensivehuman use (res- toleranceto environmentalconditions as indi- "clean" idential,recreational, agricultural, etc.) and also cated by their presencein waters satu- "pol- receiving discharges from point and nonpoint rated with dissolved oxygen, as well as in sourcesare becomingincreasingly eutrophic. As luted" waters very low in oxygen. The occur- a consequence,macrofaunal speciesdiversity in rence of certain speciesof midges in polluted these habitats is gradually decreasing and re- waters is indicative of the type of pollution in sults in the survival and profuse breeding of their habitat. Due to their adaptive nature, some morepollution-tolerant organisms, such as some midgespecies survive evenin brackish, estuarine speciesof Chironomidae that constitute a major or marine environments. Although most chiron- component of the macroinvertebrates.It should omids are aquatic, a few speciesoccur in decay- be understood that generally chironomid larvae ing organic matter, under bark, or in moist soil. play a beneficial role as an important source of In recent years, large populations of midge food for the predatory fish and some other in- larvae have been reported in different countries vertebrates in the food web of aquatic ecosys- (e.g., USA, Japan, Italy, Sudan and others). tems. The larvae also keep the aquatic environ- Somecentral Florida lakes support midge larval ment clean by consuming and recycling organic densities of 10,000-40,000/m'or higher, result- debris; hence, they are consideredhighly desir- ing in heavy emergenceof adult midges from able organisms in the ecosystem.However, the these lakes (AIi and Baggs 1982, Callahan and adult midges from some denselypopulated hab- Morris 1987, Patterson 1964). Similar larval itats frequently emergein large numbers, caus- densities of midges are encountered in some ing a variety of nuisance,economic and in some rivers and lakes of Japan (Moriya 1977,Ohno situations medicalproblems for humans residing and Shimizu 1982, Tabaru 1975. Tabaru et al. or working near their breeding sources.The ever JUNE1991 MeNecnupNt or PosrlrnRous CnrRoNolrroen increasing importance of chironomids as a pest (Cranston et al. 1981, Gad-El-Rab and Kay and the somewhat scattered literature on their 1980),Europe (Giacomin and Tassi 1988) and chemical, biological, physical and cultural con- Asia (Ito et al. 1986). It is believed that midges trol necessitatedcompilation of this review. are a potential cause of allergies worldwide (Cranstonet al. 1983).Adult midgesmay even cause anaphylactic shock in some individuals NUISANCE, ECONOMIC AND (M. Sasa,personal communication). MEDICAL PROBLEMS Chironomid larvae, too, can produce certain storage Dense swarms of midges often limit outdoor undesirable effects. When inhabiting potable lar- human activity since the adults can be inhaled and distribution systemsfor water, concern to or fly into the mouth, eyesand ears of an indi- vae may pass through taps causing reports of vidual. They are liable to cause asphyxia in householders. There are numerous parts cattle. During summer, midges seek cool and midges infesting water systemsin various (e.9., 1945a, shady places in the daytime leaving behind of the world Hafrz 1939, Flentje stained stucco,paint and other wall finishes on Wilhelmi 1925,Williams 1974).Larvae of sev- which they rest. They also soil automobiles,and eral midge speciesalso have been implicated as cover the headlights and windshields, causing agricultural pests.For example,there are several plants traffic accidents. At night, the adults are at- reports of damage to rice seedsand by tracted to light, swarming around indoor and chironomid larvae (Darby 1962,Ishihara 1972, outdoor fixtures. Adults of somesmall-sized spe- Risbec1951); members of the subfamilyOrtho- ciespass through standardscreens on doorsand cladiinae injure roots of Japanesehorseradish windows and thus create nuisanceand economic (Yokogi and Ueno 1971);and Stenochironomus (Nel- problems indoors, such as staining laundry, nelumbusfeeds on floating leavesof lotus walls, ceilings, draperies and other furnishings umbo wcifera) (Tokunaga and Kuroda 1936). as well as causing discomfort for the residents. Adult midgescause a considerableeconomic loss PREDOMINANT NUISANCE SPECIES to the hotel and tourism industry (Ali 1980b). Accumulations of deadmidges and the unsightly There are probably more than 2,500 species spider websin which midgesare trapped require of Chironomidae in North America (Coffman frequent washing and maintenance of proper- and Ferrington 1984).It is estimated that there ties. They clog automobile radiators and air- are 4,000 or more speciesof midges worldwide conditioning wall units and are a problem for (A. Soponis,personal communication). A sum- somepaint, pharmaceuticaland food processing mary of ecological and distributional data on industries where hordes of adults fly into the Chironomidae was given by Coffman and Fer- final products. The dead midges produce an rington (1984). Of the 7 subfamilies of Chiron- unpleasant odor similar to rotting fish. This omidae, speciesmost commonly encounteredin odor persists in damp weather for several days, heavy midge producing urban and suburban even afber the adults have been removed. At habitats are in the genera Chirornmus, Crypto- times, the dead adults accumulate on roads in chironnrnus, Goeldichironomw, Glyptotendipes, such quantities that they make the roads slip- D icrotendipe s, P aralnuterborniella, P olypedilum, pery, causingtraffrc hazards.At the Marco Polo Tanytarsus, Cla.dotanytarsus,Rheotanytarsus, Airport near Venice, Italy, there is a great con- Tokunagayusurika,Cricotopus, Proclad,ius, Coe- cern for the potential of airplanes skidding over latanypus, Tanypus and Pentaneura. SpeciesoI massive accumulations of dead midges on the a few other quantitatively less important genera runways, and also, of economic loss due to the may also occur in some locations. adults flying into delicate equipment (gauges) In general, Chironomus deconts,C. frommeri, mounted on the planes (E. Tsuroplis, personal Dicrotendipes californicus, Cricotopusbicinctus, communication).Midge swarmspose severe nui- C. syluestris,Procladius freemani and a few spe- sanceproblems to passengersand crewsofcargo cies of Tanytarsus are most widely distributed vesselsand other boats moving through the la- in California and are potentially pestiferous (Ali goon of Venice, thus adverselyaffecting human and Mulla 1979b). Specifically, in 1-2 m deep activity in that historically touristic area. man-made