PHYSIOLOGICAL ECOLOGY Survival and Predation of Delphastus catalinae (Coleoptera: Coccinellidae), a Predator of Whiteflies (Homoptera: Aleyrodidae), After Exposure to a Range of Constant Temperatures

1 2 ALVIN M. SIMMONS AND JESUSA C. LEGASPI

U.S. Vegetable Laboratory, USDAÐARS, 2700 Savannah Highway, Charleston, SC 29414

Environ. Entomol. 33(4): 839Ð843 (2004) ABSTRACT Delphastus catalinae (Horn) is a predator of whiteßies that has shown promise as a tool in pest management strategies. Exposure to short-term temperature extremes can affect the survival of predators in a greenhouse or Þeld environment. The B-biotype sweetpotato whiteßy, Bemisia tabaci (Gennadius), survives the winters of mild climates (where temperatures are commonly above 0ЊC), but it is not known if D. catalinae can survive such winters. The inßuence of constant temperature on the survival of D. catalinae was determined in the laboratory using eggs and nymphs of the B-biotype B. tabaci. Over 90% of the adult beetles exposed to temperature regimens of 5, 10, 15, 20, 25, 30, and 35ЊC for 24 h survived when conÞned with hosts. The lower and upper thresholds for survival over that duration were around 0 and 40ЊC, respectively; ϳ1% of the insects survived temperatures beyond these extremes. Survival of D. catalinae pupae was similar to that of adults. Adult D. catalinae survived up to 5.8 mo when conÞned on a plant infested with whiteßy eggs and nymphs and held at 25ЊC; 50% of the cohort survived for 3.4 mo. Those held ina similar test at 35 ЊC lived up to 0.6 mo. The number of immature whiteßies consumed during 24 h by adult D. catalinae generally increased with tem- peratures of 14Ð30ЊC. This study provides informationontemperaturesthat may affect the survival of D. catalinae during commercial shipment and after release for biological control in the Þeld or greenhouse, and it may help in the understanding of their ability to survive mild winters.

KEY WORDS Bemisia tabaci, Delphastus catalinae, biological control, vegetable, whiteßy

THE SWEETPOTATO WHITEFLY B-BIOTYPE, Bemisia tabaci ever, intentional releases were made in the desert (Gennadius) (also reported as Bemisia argentifolii southwest of the United States and in Hawaii (Pickett Bellows and Perring), attacks a wide range of plant et al. 1997). Additional dissemination of this species to species and is a serious pest worldwide. It attacks crops many international locations has occurred over the intemperate andtropical climates as well as crops in past several years for research and biological control Þelds and greenhouses. Although application of in- purposes (Hoelmer and Pickett 2003). D. catalinae secticides is currently the main method of control, [previously reported as Delphastus pusillus (Le- there is a pronounced interest within the agricultural Conte)] has not been vigorously investigated, and community for alternative approaches in whiteßy research conducted on this insect has primarily been management, such as the use of beneÞcial organisms. inrelationto other whiteßy species. However, several Delphastus catalinae (Horn) (Coleoptera: Coc- studies have shown its potential for the control of B. cinellidae) is a member of the coccinellid tribe Seran- tabaci (Hoelmer et al. 1993a, b, Heinz and Parrella giini, members of which are obligate whiteßy preda- 1994, Liu and Stansly 1999). D. pusillus is a species that tors (Gordon1994). This tropical beetle is nativeto lives onlyinthe easternUnitedStates, but its similar Colombia, South America, and is now found in Central appearance had previously led researchers to report it America, South America, Trinidad, Canary Islands, as D. catalinae (Gordon1994). Although D. catalinae Hawaii, Southern California, and Southern Florida is now marketed for whiteßy control, there is confu- (Gordon1994, Pickett et al. 1997). Its distributionto siononthe taxonomyof the species of Delphastus in these locations may have occurred primarily through commercial colonies. Hoelmer and Pickett (2003) re- the spread of plant materials (Gordon 1994). How- cently concluded that the species held in commercial insectary cultures is probably D. catalinae rather than This article reports the results of research only. Mention of a D. pusillus. Little is known about the overwintering proprietary product does not constitute an endorsement or recom- range and the impact of climate on the population mendation for its use by USDA. 1 E-mail: [email protected]. dynamics of D. catalinae inthe UnitedStates. Climate 2 USDAÐARS, CMAVE, Center for Biological Control, Florida is a factor that candramatically affect its Bemisia host A&M University, Tallahassee, FL 32307. (Gerling 1984, Simmons and Elsey 1995, Simmons 840 ENVIRONMENTAL ENTOMOLOGY Vol. 33, no. 4

1998). In Þeld and greenhouse environments, insects less, to minimize leaf moisture as a potential factor on are subjected to extreme temperatures. Coastal South survival, a fresh leaf was provided for all tests. For tests Carolina is the northernmost area of eastern North at temperatures above 25ЊC, anintactcollard leaf was America where the B-biotype of B. tabaci survives the used. A collard seedling, grown to the three to Þve leaf winter (Simmons and Elsey 1995). However, it is not stage ina Jiffy starter pellet (Jiffy Products of America, known if D. catalinae cansurvive evenmild winters Batavia, IL) and infested with B. tabaci eggs and (where temperatures are commonly above 0ЊC). nymphs, was set in a 5-cm-diameter plastic dish placed Elucidationof the factors that affect the efÞcacy of ontop of the cage. All leaves were detached from the predators facilitates their use as a potential manage- plant except one of a size similar to that used in tests ment component for whiteßies. To our knowledge, the for the other temperature treatments. The stem of the effect of short-term temperature extremes onthe sur- plant with the remaining leaf was turned downward vival of this insect has not been reported. Such infor- into the cage through a slit cut along one side of the mation would be useful not only for commercial rear- screening. The cut screen was overlapped and cotton ing and shipping of this insect but also for determining Þber surrounded the stem at the entrance to prevent climatic conditions affecting its efÞcacy as a biological insect escape. control tool against whiteßies. The primary objective Twenty insects were tested per cage. There were of this study was to determine the inßuence of short- one to three cages tested per trial. A total of 40 rep- term temperatures onthe survival of adult andpupal licates (cages) were tested for 25ЊC, and 5 replicates D. catalinae. The secondary objective was to deter- were tested for 50ЊC. The number of replicates for the mine survival time of adult D. catalinae onimmature other temperature treatments was a minimum of 14 B. tabaci under a moderate and a warm temperature. and a maximum of 27. Hence, a minimum of 100 and Inaddition,the predationrate of D. catalinae on B. a maximum of 800 insects were tested per treatment. tabaci immatures was evaluated under several con- The beetles were exposed to a giventest temperature stant temperature regimens. for 24 h, and the percentage of beetle survival was determined. Including 25ЊC, the insects were tested at temperatures in5 ЊC increments above and below 25ЊC Materials and Methods until no insect survived the tested temperature. After Survival of Beetles After Short-Term Exposure to exposure at each temperature, the insects were held at Different Temperatures. Insects used in this experi- room temperature (ϳ24ЊC) for ϳ1 h, and the number ment were from a greenhouse colony maintained at of live and dead beetles was recorded. Insects were not the USDA–ARS, U.S. Vegetable Laboratory, in tested at all temperatures simultaneously. Trials for a Charleston, SC. The whiteßies (B-biotype B. tabaci) giventemperature were randomizedacross time. As a have beenreared (Simmons1994) onassorted vege- control, one to three cages of beetles were tested at table crops since 1992, but feral adults from sweet- 25ЊC along with each test at the other temperatures. potato, Ipomea batatas L., were added to the colony Surviving beetles were not used in subsequent tests. annually to maintain genetic diversity. The beetles (D. An experiment was conducted using the pupal stage catalinae) were purchased commercially in1999 and similar to that for adult D. catalinae survivorship. Col- released for greenhouse pest control, and they have lard leaf disks with D. catalinae pupae were cut from persisted since the original release. The greenhouse greenhouse plants and placed on the bottom of cages colony of D. catalinae was held under temperatures with the pupae turned upward. Each leaf disk was that ranged from ϳ18 to 36ЊC. Voucher specimens of slightly greater thanthe area of the leaf occupied by the beetles were deposited at the Divisionof Plant the pupa. Pupae that appeared to be near emergence Institute, Gainesville, FL. Adult D. catalinae of un- of the adult, based on dark color, were not included in known ages were collected and conÞned in cages at the experiment. After holding the pupae at the various constant temperature in environmental chambers test temperatures for 24 h, they were held at 25ЊCto with a 16:8 (L:D) h photoperiod. Relative humidity allow emergence over 12 d. Survival of the pupae was (RH) was maintained at 80 Ϯ 15% for the temperature based ontheir ability to successfully emerge to the treatments by providing open trays of water as adult stage and exit the pupal cuticle. A minimum of needed. The adult beetles were conÞned in a cage 5 and a maximum of 15 replicates were conducted per made from a 480-ml cylindrical paper carton (8.5 cm treatment. Surviving beetles were not used again in diameter). The top of the cartonwas removed and subsequent experiments. replaced with Þne mesh screening; it was held in place Survival of Adult Beetles at Two Constant Temper- by the ring for the original top of the carton. An atures. An experiment was designed to determine lon- excised leaf (ϳ20-cm2 area) of collard, Brassica olera- gevity of D. catalinae from adult emergence to death. cea variety acephala de Condolle, which was infested The test was conducted at two constant temperatures with B. tabaci eggs and nymphs, was placed in each in environmental chambers maintained at 25 Ϯ 1and cage for the 25 Ϯ 1ЊC and lower temperature treat- 35 Ϯ 1ЊC, 16:8 (L:D) h photoperiod, and 85 Ϯ 5% RH. ments. A preliminary test indicated that excised col- Leaf disks containing D. catalinae pupae were ob- lard leaves held at test temperatures above 25ЊC ex- tained from a colony as described above and held at hibited some wilting after 24 h, but survival of D. 25ЊC. Within24 h of emergence,30 adult beetles were catalinae was not affected; at 35ЊC, survival did not placed ina cage. The cage consistedof an18 cm deep differ onintactor detached collard leaves. Neverthe- by 20 cm diameter clear plastic crisper. Two ventila- August 2004 SIMMONS AND LEGASPI:TEMPERATURE ON SURVIVAL OF Delphastus 841 tionholes of 10 cm diameter were cut onopposite sides of the cage and covered with Þne mesh screen- ing. To further secure the beetles in the cage, the cover of the container was placed on screening laid across the top of the cage. A cowpea plant, Vigna unguiculata L. Walpers, at the cotyledonto Þrst true leaf stage was established inJiffy starter pellet and infested with B. tabaci eggs and early-instar nymphs. The base of the plant with the starter pellet was placed inaninterlocking-sealplastic bag. The bag was sealed and cotton Þber was placed around the stem of the plant to prevent beetles from crawling into the bag and obtaining an additional source of moisture. The plant Fig. 1. Survivorship of adult D. catalinae of unknown ages was thenplaced inthe cage. To help provide a con- after exposure to different constant temperatures for 24 h. tinuous diverse immature host supply for the beetles, Percentage bars with different letters are signiÞcantly dif- a detached collard leaf infested with B. tabaci eggs and ferent (analysis of variance [ANOVA], P Ͻ 0.05) according nymphs was placed on the bottom of the cage. The to TukeyÕs test (SAS Institute 1999); SEM ranges from Ϯ1.8 whiteßy-infested cowpea plant was replaced every to Ϯ3.1 for the different bars. 3Ð4 d, and the whiteßy-infested collard leaf was re- placed every 1Ð2 d. Three cages were set up for each preyed on. The test was repeated 10 times for each of temperature. Each day, the numbers of dead and live the above-mentioned temperatures. beetles ineach cage were recorded untilall beetles Data Analysis. All data analyses were conducted died. The gender of the beetles was not determined. using SAS software (SAS Institute 1999). For both The experiment was repeated three times for a total of beetle stages tested, comparisons among temperature 270 beetles at each temperature regimen. Additional treatments were made on the proportions of survival data were collected onnewlyemerged adult beetles using TukeyÕs studentized range test after a arcsine for the 25 and 35ЊC temperature regimens to deter- square-root transformation to normalize the data. mine the effect of diet on survival. Adult D. catalinae Back-transformed means are presented. A similar were set up at both temperatures as described above comparisonwas doneacross trials of the check treat- with a cowpea plant but were not provided food. Data ment to test for any change in survival over the du- were collected as described above. Water was not rationof the experiment.A comparisonamongtem- provided inthe tests with or without food. perature treatments was made for mean rates of beetle Predation at Different Constant Temperature Reg- predation using TukeyÕs studentized range test. The imens. A test was conducted on the inßuence of sev- relationship between number of prey consumed and eral constant temperatures on the consumption of temperature was analyzed by regression. Unless stated immature B. tabaci by adult D. catalinae. Each test was otherwise, signiÞcant differences were determined at conducted over 24 h under temperature regimens of ␣ ϭ 0.05. 14, 18, 22, 26, 30, and 35ЊC using environmental cham- bers with a 14:10 (L:D) h photoperiod. Adult D. catali- Results and Discussion nae of unknown ages were starved for 24 h before each test ina 150-mm covered petri dish, but they were Survival of Beetles After Short-Term Exposure to provided a wet cottonball ina 35 by 10-mm dish as a Different Temperatures. Adult D. catalinae held for source of water. Arenas for the predation tests con- 24hatϪ10 or 50ЊC did not survive (Fig. 1). Survival sisted of covered 100 by 15-mm plastic petri dishes was very low (P Ͻ 0.05): ϳ1% for those held at Ϫ5ЊC provided with disks of “Burbank” tomato (Lycopersi- and those held at 45ЊC for 24 h (Fig. 1). At 5Ð35ЊC, over con esculentum Miller) plant leaßets that were previ- 90% of the beetles survived. For beetles held at tem- ously infested with B. tabaci nymphs. One to two leaf peratures of 10ЊC and below, the adults were not disks were included as needed to provide a total of active whenthey were Þrst removed from the cham- ϳ200 whiteßy eggs and nymphs per dish. No water was ber, but they became active within1 h at room tem- provided during the predation tests. For each test, the perature. Beetles held at 15ЊC were not in a chill stupor egg and nymphal stages of B. tabaci onthe disks were at the immediate end of the exposure period, but counted and recorded before introduction of the bee- movement was considerably less than at warmer tem- tles. One adult D. catalinae was placed inthe predation peratures. The performance of the pupae at the dif- dish that was put inchambers at each temperature for ferent temperatures was similar to that of the adults 24 h. After the predationperiod, the beetle was re- (Fig. 2). Several physiological factors canaffect the moved from the dish, and the number of eggs and upper and lower lethal temperatures of insects (Chap- nymphs was counted and recorded. First-instar white- man1969). Survival of starved beetles was high when ßies of the “crawler” stage at the end of the predation held at 25ЊC for 48 h (Fig. 3A); therefore, any lack of period were recorded as eggs from the pretest count. feeding in a heat or cold stupor may not have been a The total number of living whiteßies after 24 h was factor inthis study. Also, factors such as genderor age subtracted from the total count recorded before pre- apparently had no effect on the results, because sur- dation to obtain the number of eggs and nymphs vival was stable over time based onthe 25 ЊC check. 842 ENVIRONMENTAL ENTOMOLOGY Vol. 33, no. 4

likely that an effect on feeding may be a confounding factor. Nevertheless, this study was focused onthe ef- fects of relatively short-term temperature exposures on survival of D. catalinae. Wheninsectsare shipped com- mercially for biological control purposes, exposure to an extreme low or high temperature may exist for only a relatively short period. The impact of the exposure on adult beetle survival would depend on both its duration and magnitude. Similarly, in a Þeld environment where moderate winters produce temperatures that are mod- erately low for a brief time, survival might be possible. Nevertheless, our experiments on the performance of D. Fig. 2. Survivorship of D. catalinae pupae after exposure catalinae suggest that temperatures at or below freezing to different constant temperatures for 24 h; survival was may have a profound impact on survival if those tem- based on successful emergence to the adult stage. Percentage peratures are sustained for several hours. Conversely, B. bars with different letters are signiÞcantly different tabaci cantolerate much lower temperatures (Simmons (ANOVA, P Ͻ 0.05) according to TukeyÕs test (SAS Institute and Elsey 1995) than this predator. Ϯ Ϯ 1999); SEM ranges from 2.9 to 5.0 for the different bars. Survival of Adult Beetles at Two Constant Temper- atures. In the absence of food and water, newly The durationof the exposure to a temperature is ap- emerged adult D. catalinae survived up to 21 d at 25ЊC parently important to beetle survival. In a preliminary and4dat35ЊC (Fig. 3A and B). Over 50% of the test (n ϭ 12; one replication), survival of adult D. catali- beetles survived for 7 d whenstarved at 25 ЊC, whereas nae after a 48-h exposure period was high (Ͼ80%) at Ͻ50% were alive 2 d after being held without food at constant temperatures of 5, 10, 15, 20, and 25ЊC, was low 35ЊC. Whenthe adult beetles were held at 35 ЊCand (17Ð50%) at 30 and 35ЊC, and none survived at 40ЊC. provided food, they lived up to 16 d, with 56% living However, for the 24-h exposure test, 60% of the adult for 7d (Fig. 3B). Conversely, when food was provided beetles survived at 40ЊC (Fig. 1). The greater the dura- to adult beetles held at 25ЊC, survival ranged from 2 to tionof exposure to extreme temperatures, the more 174 d; 50% were alive from 73 to 102 d after emergence (Fig. 3A). During the experiment, a few adult B. tabaci emerged from pupae onthe collards, but we suspect that they were, at most, only a fraction of the diet of the beetles. Hoelmer et al. (1993b) reported onthe longevity of D. catalinae (D. pusillus inreport) when fed B. tabaci eggs at 28ЊC. Inthat study, ina petri dish arena, the females lived an average of 61 d and males lived anaverage of 45 d. The females were onlyal- lowed to mate for 1 d after emergence. Although we did not determine gender, the primary reason the beetles lived longerinour study at 25 thanat 28 ЊCin the Hoelmer et al. (1993b) study may be because of the different effect of the two temperatures. However, we do not know what effects a diet of both eggs and nymphs, or the availability of mating partners for a long period of time may have had in our study. Mating pairs were observed incopula inour experimentup to 150 d after emergence, and random checks of leaves from the cages indicated that eggs continued to be deposited at least up to that time. Legaspi et al. (1996) reported that temperature canaffect the survival of another coccinellid predator, Serangium parcesetosum Sicard; the adults survived longer at 20ЊC thanat higher temperatures. Inthat study, meanlongevity was 79 d for beetles maintained at 20ЊC, although the insects were not provided a constant whiteßy diet. Predation at Different Constant Temperature Reg- imens. The total number of prey consumed was en- hanced by temperature in a linear relationship (P Ͻ 0.004; r2 ϭ 0.17; y ϭ 97.5 ϩ 2.70x) whentested from Fig. 3. Percentages of survival of populations of adult D. Њ catalinae after emergence when held at 25 (A) or 35ЊC (B), 14 to 35 C, but predationwas similar at most of the with or without food (B. tabaci eggs and nymphs). Water was temperatures (Table 1). Ina study on S. parcesetosum, not provided in either test. A total of 270 beetles were used higher predationrates were reported at higher tem- per treatment per temperature. peratures (30 and 40ЊC) thanat 20 ЊC (Legaspi et al. August 2004 SIMMONS AND LEGASPI:TEMPERATURE ON SURVIVAL OF Delphastus 843

Table 1. Mean predation rates ؎SEM of a coccinellid predator, D. catalinae, under different constant temperatures for 24 h when provided immature whiteflies, B-biotype B. tabaci

Percentage Temperature Mean number of whiteßy immatures consumed (pretest number) of prey items (ЊC) Egg First to third instars Fourth instar Total consumed 14 109.3 Ϯ 16.0 (122.6)ab 16.5 Ϯ 5.2 (76.7)c 0.0 Ϯ 0.0 (0)a 125.8 Ϯ 19.7 (199.3)b 60.4 18 74.3 Ϯ 14.0 (89.8)b 70.0 Ϯ 7.0 (118.4)ab 0.1 Ϯ 0.1 (0.3)a 144.4 Ϯ 8.7 (208.5)ab 69.9 22 121.1 Ϯ 14.1 (149.6)ab 52.2 Ϯ 7.6 (85.9)ab 0.6 Ϯ 0.2 (1.1)a 173.9 Ϯ 18.8 (236.6)ab 72.5 26 91.2 Ϯ 24.7 (108.0)ab 70.0 Ϯ 10.3 (105.0)ab 0.7 Ϯ 0.3 (1.1)a 161.9 Ϯ 17.1 (214.1)ab 75.5 30 150.7 Ϯ 17.9 (165.4)a 37.6 Ϯ 11.1 (45.4)b 0.8 Ϯ 0.7 (1.1)a 189.1 Ϯ 11.9 (211.9)a 88.9 35 92.1 Ϯ 20.3 (107.3)ab 88.6 Ϯ 7.2 (139.5)a 0.0 Ϯ 0.0 (0)a 180.7 Ϯ 18.7 (246.8)ab 72.3

Means followed by different letters within a column are signiÞcantly different (P Ͻ 0.05) according to TukeyÕs studentized range test (SAS Institute 1999); n ϭ 10 observations per temperature; data in parenthesis are mean number of insects before introduction of the beetles.

1996). Inour study, the adult beetles consumed125Ð Heinz, K. M., and M. P. Parrella. 1994. Biological control of 189 prey items and an average of 60Ð89% of the avail- Bemisia argentifolii (Homoptera: Aleyrodidae) infesting able prey items at the different temperatures. Excess Euphorbia pulcherrima: evaluations of releases of Encar- prey remained at the end of each test (Table 1). sia luteola (Hymenoptera: Aphelinidae) and Delphastus Overall, ϳ50Ð80% of the prey consumed were eggs, pusillus (Coleoptera: Coccinellidae). Environ. Entomol. which constituted the majority of the available prey 23: 1346Ð1353. Hoelmer, K. A., and C. H. Pickett. 2003. Geographic origin items. Similarly, ϳ1% of the prey items consumed and taxonomic history of Delphastus spp. (Coleoptera: were fourth-instar whiteßy nymphs, and only a very Coccinellidae) in commercial culture. Biocontrol Sci. small percentage of the available prey were fourth ϳ Њ Technol. 13: 529Ð535. instars. Under ambient temperature ( 23 C), adult D. Hoelmer, K. A., L. S. Osborne, and R. K. Yokomi. 1993a. catalinae spend more time consuming B. tabaci as prey Interactions of the whiteßy predator Delphastus pusillus size increases from egg (0.3 min) to fourth instar (5 (Coleoptera: Coccinellidae) with parasitized sweet- min) (Liu and Stansly 1999). Within the 18Ð35ЊC potato whiteßy (Homoptera: Aleyrodidae). Environ. En- range, this predator has a high incidence of consump- tomol. 23: 136Ð139. tion in the presence of hosts, but it is not known how Hoelmer, K. A., L. S. Osborne, and R. K. Yokomi. 1993b. Re- search time may be affected across these temperatures production and feeding behavior of Delphastus pusillus (Co- whenprey is rare or absent. leoptera: Coccinellidae), a predator of Bemisia tabaci (Ho- Our experiments were designed to reßect multiple moptera: Aleyrodidae). J. Econ. Entomol. 86: 323Ð329. Legaspi, J. C., B. C. Legaspi Jr., R. L. Meagher Jr., and M. A. factors which may affect a populationof D. catalinae Ciomperlik. 1996. Evaluationof Serangium parceseto- whenit is used for biological controlina greenhouse sum (Coleoptera: Coccinellidae) as a biological control or Þeld environment. No attempt was made to deter- agent of the silverleaf whiteßy (Homoptera: Aleyrodi- mine any sublethal effects. This study demonstrates dae). Environ. Entomol. 25: 1421Ð1427. short-term lethal temperatures for adult and pupal D. Liu, T.-X., and P. A. Stansly. 1999. Searching and feeding be- catalinae and duration of survival at moderate and havior of Nephaspis oculatus and Delphastus catalinae (Co- warm temperatures. This information has implications leoptera: Coccinellidae), predators of Bemisia argentifolii for commercial rearing and shipping of these beetles (Homoptera: Aleyrodidae). Environ. Entomol. 28: 901Ð906. as well as for their performance when used for the Pickett, C. H., K. A. Hoelmer, and W. J. Roltsch. 1997. Sys- management of whiteßies. tematics of Delphastus and biological control of white- ßies, p. 165. In T. J. Henneberry, N. C. Toscano, T. M. Perring, and R. M. Faust (eds.), Silverleaf whiteßy: 1997 Acknowledgments supplement to the Þve year national research and action plan. Progress review, technology transfer, new research We thank USDA-ARS staff B. Peck and I. Baez and Florida and action plan. United States Department of Agriculture A&M University staff M. Soumare and J. Head for technical and Agricultural Research Services, Washington, D.C. assistance. We thank C. H. Pickett (California Department of SAS Institute. 1999. SAS/STAT userÕs guide, version8.2. Food and Agriculture) for Delphastus species identiÞcation SAS Institute, Cary, NC. and D. G. Riley (University of Georgia) and R. N. Ward Simmons, A. M. 1994. Ovipositiononvegetables by Bemisia (Alabama A&M University) for valuable suggestions on the tabaci (Homoptera: Aleyrodidae): temporal and leaf sur- manuscript. face factors. Environ. Entomol. 23: 382Ð389. Simmons, A. M. 1998. Survey of the parasitoids of Bemisia References Cited argentifolii (Homoptera: Aleyrodidae) incoastal South Carolina using yellow sticky traps. J. Entomol. Sci. 33: Chapman, R. F. 1969. The insects structure and function. 7Ð14. American Elsevier Publishing Company, New York. Simmons, A. M., and K. D. Elsey. 1995. Overwintering and Gerling, D. 1984. The overwintering mode of Bemisia tabaci cold tolerance of Bemisia argentifolii (Homoptera: Aley- and its parasitoids in Israel. Phytoparasitica. 12: 109Ð118. rodidae) in coastal South Carolina. J. Entomol. Sci. 30: Gordon, R. D. 1994. South AmericanCoccinellidae(Co- 497Ð506. leoptera). Part III: taxonomic revision of the western hemisphere genus Delphastus Casey. Frustula Entomol. 17: 71Ð133. Received 22 January 2004; accepted 26 April 2004.