Effects of Mesocyclops Longisetus (Copepoda: Cyclopidae)

Home , Cyclops (copepod), Mesocyclops, Mesocyclops longisetus

Journal of the American Mosquito Control Association, 12(4):688-694,1996 Copyright O 1996 by the American Mosquito Control Association,Inc'

EFFECTS OF MESOCYCLOPSLONGISETUS (COPEPODA: CYCLOPIDAE) ON MOSQUITOES THAT INHABIT TIRES: INFLUENCE OF LITTER TYPE, QUALITY, AND QUANTITY

E. T SCHREIBER.' C. E HALLMON,I K. M. ESKRIDGE, ANO G. G. MARTEN]

ABSTRACT. A 59-week study was conducted to evaluate the impact of adult Mesocyclops longisetus populations on larval mosquito species inhabiting tires. Greater than 9OVoreduction of number of lst and 2nd instars was recorded by 4 wk w\th gOEo reduction of number of 3rd and 4th instars after 7 wk. Reduced control was noted with the onset of cooler winter water temperature. Overall, a 52Va reduction in the number of lst and 2nd instars was achieved, and,a 57Vo reduction was noted in number of 3rd- and 4th-instar mosquito larvae. Cooler temperatures resulted in a decline of adult Mesocyclops, which resulted in reduced larval control. Significantly greater numbers of Mesocyclops adults were collected in tires with either new litter or heavy amounts of litter regardless of litter type. Lastly, litter type, either oak leaves or pine needles, did not influence mosquito reduction or abundance of Mesocyclops populations.

INTRODUCTION FL (Airport Authority land), primarily vegetated (Quercus pine Cyclopoids of the genus Mesocyclops are pred- with live oak virginiana Mill.), slash (Pinus with some sand pine (Pl- ators of mosquito larvae (Bonnet and Mukaida elliottil Englem.) 1957, Riviere and Thirel 1981, Marten 1984) and nus clausa Chapm. er Englem.), and magnolia (Magnolia some have been studied as potential biocontrol grandiflora Linn.). The understory was agents for mosquitoes in container habitats (Marten generally devoid of vegetation due to heavy 1990a, 1990b; Schreiber et al. 1993; T\etze et al. amounts of pine straw. The vegetation present in 1994). ln particular, Mesocyclops spp. have been this site consists of the dominant tree species in evaluated especially in Aedes aegypti (Linn.) hab- habitats throughout the Gulf of Northern Florida itats (Riviere and Thirel 1981) in Tahiti, and against (Myers and Ewel 1990). This site was chosen be- Aedes albopicras (Skuse) in the United States (Mar- cause mosquito populations were limited to a few ten 1990a, 1990b). Integrated control with biora- species, with Ae. albopictus making up the vast ma- tional larvicides appears to be the modus operandi jority (Schreiber et al. 1993, Tietze et al. 1994). for cyclopoid usage and control of pestiferous mos- Each tire pile contained 32 used automobile tires quito species inhabiting containers (Riviere et al. naturally infested with mosquitoes. The 32 tires 1987, Marten 1990b, Tietze et al. 1994). This ap- were stacked against the base of a tree and not proach has been based on reports of delayed larval against each other; they were all touching the control due to a variety of operational and environ- ground and arranged so that water inside could be mental variables including low copepod inoculation removed via a flap for examination. The flap con- rates (Marten 1990b, Schreiber et al. 1993), water sisted of 2 7.6-cm parallel cuts into one sidewall of chemistry, food value of the organic matter within a tire. The only source of water entering the tires the container (Jennings et al. 1994), as well as during the study was rainwater. Thus, some tires (n amount and type of organic matter (Schreiber et al. = 9) dried out sporadically during the study. 1993). The tire piles were placed 300 m from each other In this study, we compared the effectiveness of and were more than 100 m from other potential Ae. Mesocyclops longisetus (Thiebaud) in used auto- albopictus developmental sites, namely discarded mobile tires to control resident mosquito species for tires from the airport maintenance department. a 59-week period with 2 different litter types (oak Adult Ae. albopictus has a limited dispersal range and pine) 2 different litter amounts and age of the of no more than a few hundred meters (Hawley litter. 1988). Experimental design: Each pile averaged 111 MATERIALS AND METHODS immature Ae. albopict J per tire on August 16, 1994, when treatments were applied. There were 4 piles Study site: In late September 1993, 4 tire treatment factors: Mesocyclops (yes or no) type of were established in a wooded area of Panama City, litter (oak leaves or pine needles), amount of litter (light or heavy), and age of litter (new or old), giv- 'John A. Mulrennan, Sr., Research Laboratory, Florida ing a total of 16 treatment combinations. Treatment A&M University, 400O Frankford Avenue, Panama City, combinations were randomly assigned to 2 tires FL 32405. within each tire pile and the tire placement was 2 Department of Biometry, 103 Miller Hall, University of Nebraska-Lincoln, Lincoln, NE 68583-0712. randomized. Oak leaves were obtained from live 3 New Orleans Mosquito Control Board, 66Ol South oak ffees. Pine needle bundles were from slash pine Shore Drive. New Orleans. LA 70126. trees. Both leaf types were collected from the im-

688 Decerrasnn1996 YEAR-LoNG SruDy oF MEsocycLops LoNcTsETUS 689

mediate area of the study site with new leaves and treatment by single litter-variable interactions, the needles taken from pruned or fallen trees. Prelimi- 2-way litter-variable interactions, and the 3-way nary investigations on litter fall helped to determine treatment by litter-variable interactions. Split-plot "light" "heavy" the and amounts experimentally effects were the above effects with the additional placed into the tires. Light amounts of oak leaves effects of week (time) and pile by week interaction. were designated as 15 leaves, and light amounts of Effects of high and low temperature on M. longi- pine needles were determined to be 15 needle bun- seras populations and effects of M. longisetus ol dles (3 needles per bundle). Heavy amounts for oak individual mosquito stages were modeled utilizing leaves were l0O leaves, and 200 needle bundles curve fit option regression techniques (CA-Cricket were considered representative for slash pine. Old Graph III, Computer Associates International leaves and needles were from last year's leaf fall, 1992). The dependent variable was the mean num- taken primarily from mulch piles. Periodic removal, ber of M. longisetus adults, and the high and low by hand, from tires of naturally occurring oak leaf water temperatures obtained from maximum,/mini- and pine needle litter was conducted to maintain mum therometers placed in one tire within each tire integrity of initial litter treatments. pile were used as independent variables. The M. longisetus used in this study originated from John A. Mulrennan, Sr., Research Laboratory colonies initially received from the New Orleans RESULTS Mosquito Control Board. Mesocyclops longisetus A adults were inoculated into tires utilizing a hand total of 2,157 mosquito larvae was sampled from tires. The pump sprayer that delivered an average of ll9 -F dominant species was Ae. albopic- (88Vo). 2.4 individuals/tire (Hallmon et al. 1993). tus Culex quinquefasciatus Say, Culex sal- Immature mosquitoes and M. longisetus ad:ults inarius Coq., and Anopheles crucians Wied. com- were monitored from September 4, 1993, through prised 4.6, 3.0, and 3.lvo of the larvae collected in September 27, 1994. All tires from each tire pile our samples, respectively. Three other species were were sampled 15 times. Tires were sampled every found during the study and comprised <2Vo of the 2-6 wk with the longer duration occurring during total. They were Aedes triseriatus (Say), Culex res- the winter months. All water and litter were re- tuans Theobald, and Orthopodomyia signiftra moved from each tire and placed into a l9-liter (coq.). plastic bucket and concentrated via a 1,00o-ml plas- The impact of M. longiset r.r adults and leaf litter tic beaker with a screen mesh (24 per cm) located variables on developing lst- and 2nd-instar mos- on 2 sides of the beaker 3 cm from the bottom. quitoes varied in significance in the overall split- Individual beakers for treatment and controls were plot analyses (Table l). The effect of pile (block) = utilized. Following concentration, each tire sample was statistically significant (P 0.02). Tires con- -r -r was put into an individually marked plastic containing Mesocyclops (i SE) had 9.45 0.70 lst tainer and brought back to the laboratory for iden- and 2nd instars, whereas the control tireshad24.43 + tification. Treatment combination, number of lst l.0l lst and 2nd instars (P : 0.0001). Litter type and 2nd instars, and number of 3rd and 4th instars (T) was statistically significant (P = 0.001), with mosquito larvae were recorded. Lastly, the number tires containing pine needles having 17.46'r l.O2 of adult M. longisetus (adults based on size and lst and 2nd instars and tires with oak litter having -r presence of caudal filaments) was recorded. Ali- 16.47 0.88 lst and 2nd instars regardless of cy- quots of mosquito larvae from each tire were clops treatment. placed either in vials containing TOVo ethanol for The split-plot effects: week (W), week by treat- later species identification or examined directly un- ment (W X Trt), and week by litter type (W x T) der a stereomicroscope at the time of data record- were highly significant statistically (P : 0.0001, P ing. Following counting and identification, remain- = 0.0001, and P : 0.0007, respectively, in the ing mosquito larvae, pupae, and copepods were re- number of lst and 2nd instars collected). Addition- turned with water and litter to the respective tire. ally, the 3-way interactions: week by treatment by High and low temperatures were recorded by a litter type (W X Th x T), week by litter age by maximum/minimum thermometer placed in one tire litter type (W X Age x T), and week by litter at each tire pile location. amount by litter type (W X Amt X T) influenced Statistical analysis: Efflcacy of different treat- the number of lst and 2nd instars collected from ment combinations upon immafure mosquito stages tires. Lastly, the 4-way interaction: week by treat- (i.e., lst and 2nd instars and 3rd and 4th instars) ment by litter age by litter type (W X Trt X Age were assessed by a split-plot-in-time analysis of X T) was also significant (P : 0.04). variance, following square root transformation of The effect of litter type is illustrated in Fig. 1A. the data to stabilize error variances and Student- Through the 59-wk study, tires that had pine nee- Newman-Keuls mean separation test due to un- dles as their litter component had a greater number equal sample sizes (SAS Institute 1990). In this of lst and 2nd instars (17.46 '+ 1.02), than did tires -f study, whole-plot effects were: pile (or block) Me- with oak litter (16.47 0.88). Despite these overall socyclops treatment, individual litter variables, the mean differences large and readily observable dif- I L JouRNALon rsE At"rentcANMosQurro Coxrnor- AssoclaloN VoL. 12, No. 4

Table 1. Analysis of variance of Mesocyclops longisetus on lst and 2nd instars of mosquitoes in tires from August September1994, PanamaCitY, FL.'

df F value P>F

Pile 3.7| 0.0200 Tleatment (Tft) 239.O7 0.0001 Litter age Age) 0.86 0.3587 Litter amount (Amt) 1.09 o.3012 Litter type (T) 12.51 0.0010 Th X Age 0.04 0.8503 Trt x Amt o.oo 1.0000 TrtxT o.oo 1.0000 Age X Arnt 0.03 o.872r AgexT 0.18 o.6724 AmtxT 0.40 0.5279 TltXAgeXAmt 0.55 0.4602 TltxAgexT 2.37 0.1310 TrtXAmtXT o.25 0.6188 AgeXAmtXT o.49 0.4885 TttXAgeXAmtxT 0.65 o.4254 PilexTrtxAgeXAmtXT 45 Error a Week (W) I4 20.56 0.0001 W X Pile 42 Error b WXTrt l4 18.15 0.0001 WXAge t4 r.62 0.0700 WXAmt t4 1.50 0.1051 WXT t4 2.72 0.0007 WXTrtXAge t4 0.87 0.5926 WxTrtxAmt l4 1.54 o.o92l WXTITXT l4 3.79 0.0001 WxAgexT l4 2.69 o.0007 WXAmtXT 14 1.89 o.0246 WxAgeXAmtxT t4 o.73 o.7494 WxTttxAgexT t4 t.79 0.0364 WXTTtXAgeXAmtXT 13 0.88 0.5700 WXPileXTrtXAgeXAmtXT 618 Error c t R2 : O.77;CV : 51.69.

ferences were only noted prior to Mesocyclops in- This trend continued until the beginning of summer troduction and during the summer (weeks 40-50). (week 43). During this time tires with pine needles, Through the majority of the study's duration the regardless of age, contained the most lst and 2nd 'r control tires had greater numbers of lst and 2nd instars collected (61.88 32.22), whereas tires + instars collected than did the Mesocyclops-treated with oak leaves contained 37.53 25.09 larvae. tires. However, during the winter and beginning of As summer progressed into fall differences between spring (weeks 10-30), differences between the con- litter age and type again became difficult to distin- trols and treatment were minor or nonexistent (Fig. guish. lB). Thereafter, tires that contained Mesocyclops Seasonal differences between treatments coupled had generally less than 10 lst and 2nd instars col- with litter type were nonexistent from late fall lected/tire, whereas controls had about 25 lst and (week 12) through the winter and spring (week 35). 2nd instars/tire. Thus, the change in magnitude of Separation of individual treatment combinations differences between the 2 treatments changed on a was not evident until onset of summer (week 40) seasonal basis resulting in the week by treatment with the greatest number of larvae collected from + interaction being significant. pine needle control tires (90.28 9.94) as com- + Regardless of overall treatment, litter age by lit- pared to the pine Mesocyclops tires (31.29 3.O9). ter type interaction over the course of the study did As summer progressed to fall (week 50) and until influence the number of developing lst and 2nd in- the end of the study fewer lst and 2nd instars were stars collected from tires. Prior to inoculation with collected in tires with Mesocyclops rcgatdless of -r Mesocyclops, tires with new pine needles and old litter type (3.8S 0.05). During the same interval oak leaves contained more lst and 2nd instars than differences between control tires by litter type also did their counterparts. As the study progressed into decreased in magnitude. fall and winter, differences between litter type cou- Mesocyclops longisetus, given a choice, prefers pled with fitter age became difficult to separate. to prey upon lst and 2nd instars; however, some Dec*rssn 1996 YEAR-LoNG Sruoy or MEsocycLops L)NGISETUS

- Ch lrl -# OAKLITTER -t- PINENEEDLES u)

& - v)z

.i z z

rrl

U)F arl

? F zU)

.i z z

0102030405060 WEEK POST-MESOE]iELOPS INTRODUCTION Fall Winter Spring Summer Fall

Fig. l. Mean lst- and 2nd-instar mosquitoes from tires after introductionof Mesocyclops longisetus. A. Number of lst- and 2nd-instar mosquitoes in oak litter and pine needles. B. Number of lst and 2nd instars in tires containine Mesocyclops and controls from September 1993 to September 1994, panama City, FL.

-r predation on 3rd and 4th instars does occur. The 2 3.37 2.08 larvae. The differences most evident whole-plot effects that influenced number of 3rd were those with pine needle litter and age combi- and 4th instars in tires were treatment (with control nations, with new needleshaving fewer 3rd and -+ 4th tires having 4.4O 2.15 larvaelttre and Mesocy- instars collected (3.28 x. 2.19) than old needles 'ts clops tires 2.56 l.7l larvae/ttre, P :0.0001) and (3.68 -r 2.27). interaction between litter age by litter type (P : As with the analysesof lst and 2nd instars,many 0.O4). Differences were not readily observable with split-plot effects for the later instars were also sta- respect to larvae from tires with oak litter by age, tistically significant.The following split-plot effects with new having 3.54 + 2.O3 larvae and old having were all highly significant: week (p : O.0OOI), 692 JounNel oF THE AMERICANMosQUITo CoNrnol Assocte.noN Vol. 12,No.4

Effects on Mesocyclops populations; The different litter variables and their subsequent interactions on the collected number of Mesocyclops adults had F fr a number of significant effects. The whole-plot ef- o fects (pile, litter age, and litter amount) were sta- ? = : o tistically significant (P = 0.0O05, P O.W2, P o 0.002, respectively). Greater numbers of Mesocy- clops adults were collected in new litter, regardless 3 -r 4 of amount or type (50.94 2.00), than in old litter (33.84 -f 2.00). Greater numbers of Mesocyclops E litter o adults were collected in heavy amounts of z -+ (35.92 z (49.21 4.90) than in light amounts of litter + 0.60) through the entire study. Additionally, split-plot effects of week (W), week by litter amount (W x Amt), and week by litter type (W x 'l) on Mesocyclops abundance were statistically significant(P = 0.0001,P: O.O2,P:0.01, respectively). Fig. 2. Mean number of 3rd- and 4th-instar mosqui- A greater mean number of adult Mesocyclops toes from tires after introduction of Mesocyclops longi- was collected from tires with heavy amounts of lit- A. Mean number of 3rd and 4th instars per tire in setus. ter (58.15 + 5.14) vs. light amounts (36.66 + 3.57) Mesocyclops-treated tires vs. controls. B. Mean number of during the initial part of the study. No differences 3rd and 4th instars per tire in different litter amounts in (weeks tires from September 1993 to September 7994, Panama were noted during late winter and spring City, FL. 23-35). Observable differences returned again by summer (week 43), between heavy amounts (43.24 + 1.25) compared to light amounts (30.96 + I .04). week by treatment (P : 0.0001), week by litter Thus, the difference between litter amounts in the amount (P = O.O2$, and week by litter age by litter latter period was less than before the winter inter- type (P : 0.008). val. The week by treatment interaction is depicted in Observable differences in mean number of adult Fig. 2. Observable differences in the number of 3rd Mesocyclops collected from tires with respect to and 4th instars in tires (less in Mesocyclopr-treated oak litter and pine needles occurred regardless of tires than controls) were evident much of the year litter age or amount. During the first lO wk of the until midwinter and most of the spring months. study, no discernible trend was apparent in the During this time period no differences between number of adults collected in the 2 litter types. At treatments were readily apparent. At the onset of the onset of winter more adults were collected in -f spring (week 30) through the end of the study, ob- tires with oak litter (48.82 l.O2) than in tires with -r servable differences occurred in the number of 3rd pine needles (46.t9 0.91). Through the spring and 4th instars collected between tires with Meso- months (weeks 20-30) no observable differences in cyclops. Lastly, the abundance of 3rd and 4th in- adtit Mesocyclops abwdance were evident (both stars collected from tires with light or heavy about 20 per tire). Once summer arrived, however, amounts of litter, regardless of litter type or treat- through the end of the study, Mesocyclops adtits ment, was significant. However, the only real dif- were collected in greater numbers from tires con- ferences were noted during the 4th week (heavy taining pine litter (about 55.O/tire) compared to tires amounts had about 45.0 3rd and 4th instars/tire containing oak litter (about 34.0/tire). compared to light amounts, which had 1.O/tire). As the previous paragraphs indicated, a decline Thereafter no differences were apparent for the rest in the number of Mesocyclops adults collected was of the study. noted with the onset of winter and subsequently All litter age by litter type combinations behaved cooler water temperatures. This relationship be- similarly with respect to the number of 3rd and 4th tween mean minimum temperature and abundance instars (oscillating up and down) collected through of adult M. longisetus in tires is expressed mathe- the study period. However, no single litter age by matically and graphically in Fig. 3. The regression type combination consistently yielded more 3rd and model illustrated that when mean minimum water 4th instars than the other combinations for any par- temperatures were between 7 and l7oC, numbers of ticular length of time of the study. However, some adult M. longisetus were relatively constant. A generalizations can be inferred: tires that had either sharp decline in abundance of M. longisetus was -r old oak litter (17.96 O.O2) or new pine needles noted once the mean minimum temperature went (22.87 t- 0.13) had the greater number of 3rd and below 5'C. Minimum temperatures that are, on av- 4th instars collected than did tires new oak litter erage, below this range resulted in a dramatic de- (17.15 1- 0.16) or old pine needle (21.97 t 0.13) crease in numbers of M. longisetur adults, whereas over the entire study. higher temperatures resulted in an increase. Dpcprusen1996 Yem-LoNc SrrDy oF Mzsocvctops toNGIsETUS

litter variables measured, although statistically significant, did not appear to have any real biological a8o tul consequence due the overriding effect of abiotic ol JI (i.e., 9l factors minimum water temperatures; con- floo trtr founded in this study with weeks) with differences q in the mean number of lst and 2nd or 3rd and 4th ! ;40 o instars between and among various treatment com- z binations. The effect of litter type associated with z abundance of lst and 2nd mosquito instars maybe a result of ovipositional preferences by gravid Ae. albopictus due to water chemistry via leached or-

051015202530ganics from their resident leaves (i.e., tannins, lig- nins, and terpenoids). Furthermore, the significance towtglpoc of pile effect with respect to the number of lst and Fig. 3. Regressionline (y = O.O4x31' 7.76x2+ 21.39x 2nd instars may in part be explained by some ovi- - 23.60, f = O.77) of the mean number of adult Meso- positional preference by Ae. albopictus in our tire cyclops longisetus collected from tires at different mean piles. Indeed, the pile effect was not significant minimum water temperaturesfrom September 1993 to with respect to 3rd and 4th instars. September1994, PanamaCity, FL. Water chemistry has been shown to be an important factor in oviposition and development for a number of mosquito species (Petersen and Chap- DISCUSSION man 1969, Bradshaw and Holzapfel 1986, Walker Classical biological control agents regulate pest and Merritt 1988, Bentley and Day 1989, Walker populations of interest rather than eliminating them et al. 1991). Other studies suggested that leached as do current chemical control procedures. Meso- chemicals have an indirect reducing effect by lim- cyclops longisetus introduced into tires to reduce iting the number of microorganisms available for larval mosquitoes works in this fashion during the consumption of developing mosquitoes (Walker et majority of the year. However, our results showed al. 1988, 1991; Sota 1993). Similarly, the effects of that M. longisetus populations failed to control the the biological and physiochemical attributes of con- target mosquito population during the winter tainers for copepod production have been investi- months when minimum water temperatures gated (Jennings et al. 1994). Those authors found dropped below l0t. In our study, this was from that low levels offood for the developing copepods about week 17 to week 35 (January through April). were pivotal in survivorship of Mesocyclops asper- In spring, both the mosquito and copepod popula- icornis (Daday), along with pH and salinity. Our tions increased in size and it was not until week 39 study did not examine these factors; rather, we in- (May) that Mesocyclops populations had recovered vestigated the broad categories such as litter type, enough to have an impact on developing lst- and amount, and age. 2nd-, and 3rd- and 4th-instar mosquito populations The rate of 119 M. longisetus per tire appears to (7l%o and 68.5Vo redtction as compared with the be an adequate number for field application. At this controls, respectively). Thus, low water tempera- rate, reduction in larval mosquitoes was achieved ture is an important component factor diminishing relatively quickly and was of long duration. Winter the efflcacy and survival of M. longiselas. Decline temperatures will reduce control in much of the of Mesocyclops efficacy following the winter sea- United States, so applications of M. longisetus in son needs to be factored into any integrated man- spring may be required once the low-temperature agement strategy (i.e., reapplication of Mesocyclops theoretical threshold of l0'C is exceeded, or an ap- to target containers in the spring) to reduce con- plication of Bacillus thuringiensis var. israelensis tainer-inhabiting mosquitoes in more temperate (B.t.i) to allow for copepod populations to recover regions. Conversely, regions that do not reach these may be prudent. low temperatures may achieve lasting and continual control of mosquitoes without augmentation releas- Our findings showed that litter type, amount of es. litter, and litter age were not important in the effi- The type, amount, and age of litter in tires did cacy and growth of M. longiserzs populations, as influence control efficacy of copepods on different was first hypothesized in earlier studies (Schreiber mosquito stages based on statistical significance; et al. 1993, Tietze et al. 1994). Thus, these domi- however, only litter type had a large enough effect nant litter types in northern Florida should be of no to be biologically meaningful (tires with oak litter concern to mosquito control workers when apply- had a mean of 16.5 larvae, whereas tires with pine ing M. longisetus in the field for reduction of con- needles had 17.5 larvae) for lst and 2nd instars. tainer-inhabiting mosquitoes. Rather, the abiotic The effect of litter type, however, was not evident factor, water temperature, is of pivotal importance in the later mosquito stages (P : O.72). The other in achieving season-long control with this copepod. JounNlr op rHr Avrnrcet Mosqurro CoNIrnoLAssoclerlon Vor-.12, No.4

REFERENCES CITED de Aedes (Stegomyia) aegypti et de Ae. (St.) polyne- sienrs (Diptera: Culicidae). Essais preliminaries d'util- Bentley, M. D. and J. E Day. 1989. Chemical ecology isation coome agent de lutte biologique. Entomophaga and behavioral aspects of mosquito oviposition. Annu. 26:427-439. Rev. Entomol. 34:4O1-421. B. Kay, M. Klein and Y. Sechan. 1987. Bonnet, D. D. and T, Mukaida. 1957. A copepod preda- Riviere, F, H. J. (Copepoda) ceous on mosquito larvae. Mosq. News 17:99-100. Mesocyclops longisetus and Bacillus thu- Bradshaw, W. E. and C. M. Holzapfel. 1986. Habitat seg- ringiensis var. israelensis for the biological control of regation among European tree-hole mosquitoes. Natl. Aedes and Culex vectors (Diptera: Culicidae) breeding Geogr. Res. 2:167-178. in crab holes, tree holes, and artificial containers. J. Computer Associates International. 1992. Cricket Graph Med. Entomol. 24:425-43O. III software package version 1.0. Computer Associates, SAS Institute. 1990. SAS procedures guide, version 6, Isandia, NY. 3rd ed. SAS Institute Inc., Cary, NC. Hallmon, C. E, A. M. Lopez, W. L. Turner and E. T, Schreiber, E. T,, W. L. Turner III, A. M. Lopez, C. F Schreiber. 1993. A modified hand-pump sprayer for the Hallmon and G. G. Marten. 1993. Evaluation of two distribution of copepods for the control of container cyclopoid copepods for Aedes albopictus control in tires breeding mosquitoes. J. Fla. Mosq. Control Assoc. 64: in the panhandle of Florida at low introduction rates. J. 82-83. Fla. Mosq. Control Assoc. 64:73-77. Hawley, W. A. 1988. The biology of Aedes albopictus. Sota, T 1993. Performance of Aedes albopiaas and A. J. Am. Mosq. Control Assoc.4(Suppl. l):l-40. riversi larvae (Diptera: Culicidae) in waters that contain Jennings, C. D., J. G. Greenwood and B. H. Kay. 1994. tannic acid and decaying leaves: is the treehole species Response of Mesocyclops (Cyclopoida: Copepoda) to better adapted to treehole water? Ann. Entomol. Soc. biological and physiological attributes of rainwater. En- Am. 86:450-457. -486. viron. Entomol. 23:'4'79 Tietze, N. S., P G. Hester, K. R. Shaffer, S. J. Prescott Marten, G. G. 1984. Impact of the copepod Mesocyclops and E. T Schreiber. 1994. lntegrated management of pilosa leuckarti and the green algae Kirchneriella ir- waste tire mosquitoes utilizing Mesocyclops longisetus regularis upon larval Aedes albopictus (Diptera: Culic- (Copepoda: Cyclopidae), Bacillus thuringiensis var. is- idae). Bull. Soc. Vector Ecol. 9:1-5. raelensis, Bacillus sphaericu.s, and methoprene. J. Am. Marten, G. G. 1990a. Evaluation of cyclopoid copepods Mosq. Control Assoc. 10:363-373. for Aedes albopictus control in tires. J. Am. Mosq. Con- Walker, E. D. and R. W Merritt. 1988. The significance trol Assoc. 6:681-688. of leaf detritus to mosquito (Diptera: Culicidae) pro- Marten, G. G. 1990b. Elimination of Aedes albopictus ductivity from tree holes. Environ. Entomol. 17:199- from tire piles by introducing Macrocyclops albidus (Copepoda: Cyclopidae). J. Am. Mosq. Control Assoc. 206. 6:689-693. Walker.E. D.. E. J. Oldsand R. W. Merritt. 1988.Gut Myers, R. L. and J. J. Ewel. 1990. Ecosystems of Florida. content analysis of mosquito larvae (Diptera: Culicidae) University of Central Florida Press, Orlando, FL. using DAPI stain and epifluorescence microscopy. J. Petersen, J. J. and H. C. Chapman. 1969. Chemical fac- Med. Entomol. 25:551-554. tors of water in tree holes and related breeding of mos- Walker, E. D., D. L. Lawson, R. W. Merritt and M. J. quitoes. Mosq. News 29:29-36. Klug. 1991. Nutrient dynamics, bacterial populations, Riviere, E and R. Thirel. 1981 La predation du copepode and mosquito productivity in tree hole ecosystems and Mesocvclops leuckarti pilosa (Crustacea) sur les larvae microcosms. Ecology 7 2:1529 -1526.

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