BIOLOGICAL CONTROLÐPARASITOIDS AND PREDATORS Potential Interactions Between Pupal and Egg- or Larval-Pupal of Tephritid Fruit

1 XIN-GENG WANG AND RUSSELL H. MESSING

College of Tropical Agriculture and Human Resources, University of Hawaii, 7370 Kuamoo Road, Kapaa, HI 96746

Environ. Entomol. 33(5): 1313Ð1320 (2004) ABSTRACT This study investigated the interactions of the pupal fruit ßy , Dirhinus giffardii Silvestri, with each of four egg- or larval-pupal fruit ßy parasitoids: Fopius arisanus (Sonan), Diachasmimorpha longicaudata (Ashmead), Diachasmimorpha kraussii Fullaway, and Psyttalia con- color (Sze´pligeti) in Hawaii. F. arisanus attacks eggs, whereas the other three attack host larvae; all four parasitoids emerge from host puparia. D. giffardii attacked host puparia that had been previously parasitized by all of the other four parasitoids. Attacks by D. giffardii on young ßy puparia in which the secondary (parasitoid) host pupae had not fully formed resulted in high offspring mortality of D. giffardii compared with those developing on older host puparia, in which the host pupae had fully formed. Adult D. giffardii that developed on secondary host species were smaller and had higher mortality than those reared from the primary host, the Mediterranean fruit ßy, Ceratitis capitata (Wiedemann). Developmental timesof male and female D. giffardii were not affected by the host species. D. giffardii preferred to attack older rather than younger host puparia. D. giffardii also preferred to attack the primary rather than the secondary host species and invested more female offspring in primary than in secondary host species. Because of its nature of facultative hyperpara- sitism, D. giffardii may pose signiÞcant nontarget risks to other primary fruit ßy parasitoids.

KEY WORDS biological control, ectoparasitoids, fruit ßy parasitoids, hyperparasitism, nontarget impact

CLASSICAL BIOLOGICAL CONTROL OF tephritid fruit ßy caudata and D. tryoni were found to attack a nontarget pests using parasitoids has been successful in a few gall-forming tephritid, Eutreta xanthochaeta (Ald- subtropical and tropical regions (Wharton 1989, Pur- rich), that wasdeliberately introduced for the control cell 1998, Ovruski et al. 2000). In Hawaii, successful of the weed, Lantana camara L. (Duan et al.1998). At establishment of several hymenopteran parasitoids present, there is a lack of information on the impor- such as the egg-pupal parasitoid Fopius arisanus tance of pupal fruit ßy parasitoids and their potential (Sonan) and larval-pupal parasitoids Fopius vanden- interactionswith other egg- and larval-pupal fruit ßy boschi (Fullaway), Diachasmimorpha longicaudata parasitoids, although several pupal parasitoids were (Ashmead), Diachasmimorpha tryoni (Cameron), and among the earliest introductions from West Africa to Psyttalia incisi (Silvestri) has resulted in signiÞcant Hawaii for fruit ßy biocontrol, including Dirhinus suppression of two major tephritid pests: the Medi- giffardii Silvestri, Coptera spp., and Pachycrepoideus terranean fruit ßy, Ceratitis capitata (Wiedemann), vindemmiae Rondani (Silvestri 1914, Clausen et al. and the oriental fruit ßy, Bactrocera dorsalis (Hendel) 1965, Wharton 1989, Purcell 1998). (see Purcell 1998 for a review). However, the use of Most egg- or larvae-attacking fruit ßy parasitoids are classical biological control in agricultural ecosystems endoparasitic koinobionts (Wharton et al. 2000, Wang has become subject to increasing scrutiny with regard et al. 2003); they complete development in host pupae to nontarget impactsof introduced parasitoidsagainst within puparia and thusare vulnerable to attack by both endemic and exotic beneÞcial species (Howarth pupal parasitoids (Sivinski et al. 1998, Wang and Mess- 1991, Follett and Duan 1999, Henneman and Mem- ing 2004b). Some pupal fruit ßy parasitoids are facul- mott 2001, Louda et al. 2002). tative hyperparasitoids. For example, the chalcid, Several studies have raised concerns about the po- Spalangia gemina Boucek, can oviposit in puparia of tential nontarget impact of introduced larval-pupal the Mexican fruit ßy, Anastrepha ludens (Loew), that fruit ßy parasitoids in Hawaii. For example, D. longi- have been previously parasitized by D. longicaudata (Sivinski et al. 1998). Furthermore, S. gemina doesnot 1 Corresponding author: College of Tropical Agriculture and Hu- discriminate between parasitized and unparasitized man Resources, University of Hawaii, 7370 Kuamoo Rd., Kapaa, HI pupae and developsin both (Sivinskiet al. 1998). P. 96746 (e-mail: [email protected]). vindemmiae isable to attack two parasitoidsof Dro-

0046-225X/04/1313Ð1320$04.00/0 ᭧ 2004 Entomological Society of America 1314 ENVIRONMENTAL ENTOMOLOGY Vol. 33, no. 5 sophila larvae, Asobara tabida Neesand Leptopilina We Þrst determined if D. giffardii can attack four heterotoma (Thomson) (van Alphen and Thunnissen other fruit ßy parasitoidsinHawaii and the effectsof 1983), aswell asa number of tephritid fruit ßy para- these secondary host species and host puparia age on sitoids (Wang and Messing 2004b). Dresner (1954) the offspring Þtness of D. giffardii compared with reported that D. giffardii could attack B. dorsalis pu- those developing in the primary host C. capitata. We paria previously parasitized by F. vandenboschi in Ha- then determined if the parasitoid prefers to attack the waii and has only a slight preference for unparasitized primary rather than the secondary host species to over parasitized puparia. However, detailed informa- understand potential nontarget risk by this generalist tion islacking on potential interactionsbetween D. parasitoid. giffardii and other principal fruit ßy parasitoids in Hawaii. Materials and Methods Some aspects of the biology of D. giffardii have been documented (Dresner 1954, Podoler and Mazor Hosts and Parasitoids. Ceratitis capitata, Bactrocera 1981a, b). The parasitoid is native to West Africa, latifrons (Hendel), F. arisanus, and D. longicaudata where itsoriginal hostis C. capitata (Silvestri 1914, were provided by the mass-rearing facility of USDA- Dresner 1954). It has been introduced into Ͼ20 coun- ARS PaciÞc Basin Agricultural Research Center, Ho- tries, mainly in the PaciÞc and Central American re- nolulu, HI. eggs of both species, incubated on a gions(Noyes2002). It wasintroduced into Hawaii and wheat-based artiÞcial diet (Tanaka et al. 1969) in plas- Italy during 1912Ð1913 for the control of C. capitata tic containers(20 by 12 by 4 cm), and hostpuparia and the olive fruit ßy, Bactrocera oleae (Gmelin), re- parasitized by the two parasitoids were shipped spectively (Silvestri 1914, Clausen et al. 1965, Wharton weekly from the rearing laboratory to the Kauai Ag- 1989), and later was trans-shipped from Hawaii to ricultural Research Center (KARC), where all rearing Israel for control of C. capitata (Rivnay 1968). The and experimentswere performed under laboratory parasitoid was also introduced for control of other conditions(23 Ϯ 1ЊC, 65 Ϯ 10% RH, LD 12:12 h, 3500 fruit ßy pests in the genera Anastrepha, Bactrocera, lux). When ßy eggsdeveloped into third-instarlarvae Ceratitis, and Dacus in Australia, Central America, in the rearing container, some larvae were used for Pakistan, and Samoa, respectively (Noyes 2002). Be- parasitization by larval-pupal parasitoids to obtain pre- sides those tephritid fruit ßy species, the parasitoid can viously parasitized host puparia for later tests, while also successfully parasitize other dipterous hosts such the remainder were reared to obtain puparia or adult ashouseßies(Noyes2002).In Hawaii, D. giffardii has ßiesby placing the rearing container into a Fiberglass become widely established, although its importance box (45 by 30 by 15 cm) containing 1.5 cm of sand (ßy hasnever been documented (Purcell 1998). larvae pupate in the sand). Emerged adult of This study addresses the potential impact of D. each species were held in screen cages (25 by 25 by 25 giffardii asa hyperparasitoidof the egg-pupal fruit ßy cm) with water and honey provided in the laboratory. parasitoid F. arisanus and three larval-pupal fruit ßy Laboratory populationsof D. kraussii, P. concolor, parasitoids D. longicaudata, Diachasmimorpha kraussii and D. giffardii were established at KARC. D. kraussii Fullaway, and Psyttalia concolor (Sze´pligeti). F. arisa- wasreared on B. latifrons, the most suitable host nus iscurrently the dominant fruit ßy parasitoidin (Messing and Ramadan 2000), whereas P. concolor was Hawaii (Bess et al. 1961, Haramoto and Bess 1970, reared on C. capitata using a similar method. Approx- Wong et al. 1984, Purcell et al. 1998), partly because imately 300 third-instar larvae were placed in an ovi- of its competitive superiority against larval-pupal fruit position unit (modiÞed petri dish, 9 cm diameter and ßy parasitoids (van den Bosch and Haramoto 1953, 0.8 cm deep) with diet, and the petri dish was exposed Wang and Messing 2002, 2003, Wang et al. 2003). It is to 100Ð150 pairsof 1- to 2-wk-old adult parasitoidsin currently the only egg-attacking fruit ßy parasitoid a cage for 24 h. The exposed host larvae together with extant in the Western Hemisphere (Wharton 1989, diet were transferred to a plastic container (5.5 by 9.5 Purcell 1998, Ovruski et al. 2000), although two addi- by 10.5 cm) and placed into a holding box containing tional egg-attacking parasitoids, Fopius caudatus sand (for detailed procedures see Wang and Messing (Sze´pligeti) and Fopius ceratitivorus Wharton, are in 2002). quarantine in Guatemala (Lopez et al. 2003) and Ha- Dirhinus giffardii were initially established in the waii awaiting release permits (R.H.M., unpublished laboratory of M. W. Johnson in the University of Ha- data). D. longicaudata is one of the most widely es- waii at Manoa, Honolulu, HI, from Þeld collectionsof tablished fruit ßy parasitoids in the world (Purcell parasitized fruit ßy puparia from the Island of Hawaii, 1998, Ovruski et al. 2000). With recent developments and were later trans-shipped to KARC. Pilot experi- in mass-rearing technology, both F. arisanus and D. ments were Þrst conducted to determine the suitable longicaudata have potential for augmentative release host stages for rearing and experiments with D. giffar- for the control of tephritid pests (Purcell 1998, dii. Preliminary dissections showed that D. giffardii Ovruski et al. 2000). D. kraussii and P. concolor were reach an egg maturation peak 6Ð10 d after emergence recently reintroduced into Hawaii from Australia and with four to six mature eggs and that it can attack all West Africa, respectively, as part of a renewed effort stages of host puparia, including the late larval or to import additional parasitoids for the control of te- prepupal stage in young puparia (Table 1). It took 1Ð2, phritid pests (Messing and Ramadan 2000, Wang and 2Ð3, and 4Ð5 d for the tephritids, F. arisanus, and the Messing 2002). three larval-pupal parasitoids to develop into a fully October 2004 WANG AND MESSING:POTENTIAL INTERACTIONS IN FRUIT FLY PARASITOIDS 1315

Table 1. Life history of C. capitata and its associated parasitoids

Developmental time and stage (in days at 23 Ϯ 1 ЊC) Host species 1Ð2 3Ð9 10Ð11 12Ð13 13Ð14 14Ð15 20Ð22 22Ð24 30Ð32 Primary host Egg Larva • Puparium – C. capitata EL PPP P P A – Secondary hosts F. arisanus EL L PPP P P A – D. longicaudata ELLPPPPPA D. kraussii ELLPPPPPA P. concolor ELLPPPPPA –

Arrow indicatesthe attackable stagesoftephritid puparia by the pupal parasitoid, D. giffardii. Note within a younger puparium the host pupa hasnot yet formed. E, egg; L, larva; PP, prepupa; P, pupa; A, adult. formed pupa within a puparium, respectively, at 23 Ϯ puparium and the pupal body, and the pupa was 1ЊC (Table 1). We used 2- to 3-d-old C. capitata pu- clearly visible under a microscope. Thus, all host pu- paria in all rearing of D. giffardii by placing Ϸ100Ð200 paria were examined and chosen under a microscope. puparia in a petri dish and exposing the petri dish to However, it was difÞcult to distinguish puparia para- Ϸ100 pairsof 6- to 10-d-old D. giffardii adultsin a cage sitized by F. arisanus from unparasitized young pu- for 1Ð2 d. Appropriately equal numbersof emerged paria because there was no oviposition scar on the adult male and female D. giffardii were held in cages puparium surface. Only older puparia were used for (25 by 25 by 25 cm), with water and honey provided. the tests with F. arisanus. We used 6- to 10-d-old naõ¨ve female wasps (i.e., with- For each test, 50Ð100 puparia were placed in a petri out oviposition experience) in all experiments. dish and were exposed to Ϸ50 female D. giffardii for To obtain host puparia previously parasitized by F. 24 h in a cage. After thisexposure,one-half the puparia arisanus, C. capitata eggswere collected by exposing were dissected within 2Ð3 d to determine by a papaya fruit (8Ð10 cm diameter) in a cage (25 by 25 D. giffardii. Healthy D. giffardii eggshatched within by 25 cm) holding 150 pairsof 1- to 2-wk-old adult ßies. 2 d under these laboratory conditions. During the The infested fruit was exposed to Ϸ150 pairsof 1- to dissection, dead D. giffardii eggs(i.e., that failed to 2-wk-old F. arisanus in a cage for 24 h. The exposed hatch after 2 d) were also counted. The other half of fruit wasplaced over ßy diet in a container (9.5 by 10.5 the exposed puparia were transferred into a small by 13 cm). When the larvae started to pupate, the container (3 by 5 by 4 cm) and reared until ßiesor rearing container wasplaced into a holding box con- parasitoidadultsemerged. Asa control, we reared taining sand (for detailed procedures see Wang and 25Ð50 previously parasitized or unparasitized puparia Messing 2003). C. capitata puparia parasitized by D. for each of the tests. The body size (length), devel- longicaudata were obtained using similar procedures opmental time, and sex of each emerged parasitoid asdescribedabove for P. concolor. were recorded. On emergence, all adult wasps were All rearing and experimentswere conducted under chilled in a refrigerator (6Ð7ЊC) for 12 h and individ- the same laboratory conditions described above; the ually measured for maximum body length (from an- following three experimentswere conducted. terior edge of head to the abdominal terminus) under Facultative Hyperparasitism. In no-choice experi- a microscope. Because body length is strongly corre- ments, we exposed the following to D. giffardii: (1) lated with dry body weight in D. giffardii (Wang and unparasitized C. capitata puparia; (2) C. capitata pu- Messing 2004a), we used length as an index of body paria that were parasitized previously by F. arisanus, size. All dead puparia from each test were dissected, D. longicaudata, or P. concolor; and (3) B. latifrons and the number of unemerged adultswasrecorded. puparia that were parasitized previously by D. kraussii. Here, adult emergence rate referred to the percentage For each host species, we tested both 0- to 1-d-old of adult wasps that successfully emerged to the total puparia in which the host pupae had not yet formed number of waspsthatdeveloped to adults(i.e., and older puparia (for the actual age, see Table 3), in emerged plusunemerged adults).Premature mortal- which the host pupae had fully formed. ity was estimated based on the following formula: For each host species, newly formed puparia were ϭ ͑ ϫ Ϫ ͒ ͑ ϫ ͒ collected daily, and the two groupsof different age M N P W / N M0 puparia were prepared. Host puparia previously par- asitized by larval parasitoids were distinguished from where M isthe estimatedimmature mortality of D. unparasitized puparia by oviposition scars on the cu- giffardii; N isthe number of puparia reared for each ticle of the puparium or by observing the adult ap- test; P is the percentage parasitism by D. giffardii pendages of unparasitized 2- to 3-d-old ßy pupae vis- based on dissections (N ϫ P isthusthe expected ible through the cuticle. Inside a parasitized older number of D. giffardii adultsfrom the rearing); W is puparium, there wasa relatively large gap between the the actual number of D. giffardii that developed into 1316 ENVIRONMENTAL ENTOMOLOGY Vol. 33, no. 5

(Table 2. Effect of host species on the size and developmental time of D. giffardii (23 ؎ 1 °C

Wasp length (mm) Developmental time (days) Host species Female Male Female Male C. capitata 3.47 Ϯ 0.04 (66)a 3.10 Ϯ 0.03 (71)a 35.0 Ϯ 0.27a 32.9 Ϯ 0.29a F. arisanus 2.89 Ϯ 0.06 (20)b 2.51 Ϯ 0.04 (45)b 34.8 Ϯ 0.48a 32.8 Ϯ 0.31a D. longicaudata 2.94 Ϯ 0.06 (21)b 2.56 Ϯ 0.05 (52)b 34.9 Ϯ 0.48a 32.8 Ϯ 0.40a D. kraussii 3.04 Ϯ 0.05 (31)b 2.61 Ϯ 0.04 (64)b 34.8 Ϯ 0.39a 32.8 Ϯ 0.27a P. concolor 2.90 Ϯ 0.05 (33)b 2.60 Ϯ 0.04 (49)b 34.8 Ϯ 0.38a 32.9 Ϯ 0.29a

Values(mean Ϯ SE) followed by different letters within each column were signiÞcantly different (ANOVA, Tukey HSD test, P Ͻ 0.05). Figures in brackets are the sample sizes.

adultsfrom each rearing; and M 0 isthe control mor - parasitized puparia were chosen as in the previous test tality. through external examination under a microscope. The testwasrepeated 7Ð13 timesfor each secondary The test was conducted in a small cage (9.5 by 10.5 (parasitoid) host species and 25 times for the primary by 13 cm), with Þve parasitized and Þve unparasitized (ßy) host. Mean wasp size and developmental time puparia placed together on sand in the center of the were estimated by pooling all individuals reared from petri dish. The petri dish was placed inside the cage the same host species. Because the premature host with water and a droplet of honey, and a naõ¨ve female mortality washigh, only a few adult waspswerereared D. giffardii taken directly from the holding cage was from the young puparia, and their developmental time released into the experimental cage. After the 24-h and size were not analyzed. exposure, all puparia were dissected within 1Ð2 d to Preference Between Two Different Host Stages. In determine the number of both typesof puparia par- thisexperiment, we chose C. capitata and F. arisanus asitized. The experiment was repeated 25 times. asmodel speciestofurther determine if the parasitoid To determine the effect of host species on the sex prefersto attack old versusyoungpuparia in a choice allocation strategy of D. giffardii, an additional 20 experiment. Both young and old puparia were ob- replicationswere conducted, with all the exposedpu- tained asin the above experiment. A singlefemale D. paria reared until ßiesor waspsemerged.Sex ratio was giffardii wasprovided with Þve young and Þve old estimated based on the emerged wasps. puparia for 24 h. Data Analysis. All comparisonsofmean valuesof The test was conducted in a small cage (9.5 by 10.5 parasitoid size and developmental time, mortality, by 13 cm). A wet tissue paper was spread over a petri emergence rate, sex ratio, and percentage parasitism dish (7 cm diameter) and covered with 1.5 cm of sand. among the different treatmentswere performed using The young and old puparia (10 puparia in total) were one-way ANOVA (JMP 4.1, SAS Institute, Cary, NC). placed together on the sand in the center of the petri All proportional data were transformed by arcsine dish. The wet paper was used to keep the sand moist, square root before an analysis of variance (ANOVA). preventing desiccation during the experiment. The If a signiÞcantdifference among treatmentswasde- petri dish was placed inside the cage with water and tected, the mean valueswere subjectedto multiple a droplet of honey, and a female D. giffardii (naõ¨ve, comparisons using Tukey honestly signiÞcant differ- without oviposition experience) taken directly from ence (HSD) test. the holding cage wasreleasedinto the experimental cage. After this exposure, all puparia were dissected Results within 2Ð3 d to determine the percentage parasitism of each age group. During the dissection, the number of Facultative Hyperparasitism. Dirhinus giffardii was dead D. giffardii eggs(failed to hatch within 2Ð3 d) a facultative hyperparasitoid and could develop on all wasrecorded. The testwasrepeated 15 times.Data on of the four other parasitoids: F. arisanus, D. longicau- egg mortality were pooled with data from the dissec- data, D. kraussii, and P. concolor. Adult D. giffardii tion in the previousexperiment. reared from itsprimary host( C. capitata) were sig- Preference Between Primary and Secondary Host niÞcantly larger than those reared from any of the ϭ Ͻ Species. Thisexperiment wasto further determine if four secondary host species (female: F4,166 37.9, P ϭ Ͻ D. giffardii prefersthe primary ( C. capitata)tosec- 0.001; male: F4,278 45.2, P 0.001; Table 2). There ondary (parasitoids) host, using D. longicaudata asa was no signiÞcant difference among the size of the model species in a choice test. A single female D. wasps reared from any of the four secondary host giffardii wasprovided with Þve 2- to 3-d-old unpara- species(Table2). Developmental timesof both male sitized C. capitata puparia and Þve 5- to 6-d-old C. and female D. giffardii were unaffected by their host ϭ ϭ ϭ capitata puparia parasitized previously by D. longicau- species (female: F4,166 0.09, P 0.98; male: F4,278 data for 24 h. The total number of hosts (10) provided 0.07, P ϭ 0.99; Table 2). washigh relative to the parasitoidÕsnormalmature egg Dirhinus giffardii could attack the newly formed load (four to six mature eggs) to maximize the possi- (0Ð1 d old) host puparia of both unparasitized and bility of preferred selection for the primary rather previously parasitized hosts (by all four parasitoids) in than the secondary host species. These previously no-choice tests(Table3). In thisexperiment, we did October 2004 WANG AND MESSING:POTENTIAL INTERACTIONS IN FRUIT FLY PARASITOIDS 1317

Table 3. Effects of host species and age on the offspring survival and adult emergence of D. giffardii

Host species Percent Rearing (%) Age (days) N and age parasitism Immature mortality Adult emergence Control mortality Young puparia C. capitata 0Ð1 7 78.4 Ϯ 4.5 25.9 Ϯ 4.7a 93.4 Ϯ 3.4a 20.4 Ϯ 2.3a D. longicaudata 0Ð1 10 37.4 Ϯ 6.9 38.2 Ϯ 3.7b 96.9 Ϯ 2.7a 45.2 Ϯ 5.6b D. kraussii 0Ð1 7 42.5 Ϯ 7.5 42.6 Ϯ 5.1b 92.8 Ϯ 3.6a 42.6 Ϯ 3.2b P. concolor 0Ð1 7 60.8 Ϯ 8.1 41.1 Ϯ 4.7b 95.3 Ϯ 3.4a 42.9 Ϯ 4.6b Old puparia C. capitata 2Ð3 25 54.1 Ϯ 7.5 13.9 Ϯ 2.6A 96.8 Ϯ 2.5A 9.9 Ϯ 1.8A F. arisanus 3Ð4 12 35.4 Ϯ 5.1 29.7 Ϯ 3.8B 95.2 Ϯ 2.3A 28.5 Ϯ 4.5B D. longicaudata 4Ð5 13 33.9 Ϯ 4.7 24.9 Ϯ 3.2B 93.9 Ϯ 2.9A 35.0 Ϯ 5.4B D. kraussii 4Ð5 10 46.7 Ϯ 8.9 29.2 Ϯ 4.6B 91.4 Ϯ 2.9A 29.5 Ϯ 4.8B P. concolor 4Ð5 10 65.4 Ϯ 8.2 32.1 Ϯ 4.6B 91.1 Ϯ 2.9A 34.0 Ϯ 4.3B

Values(mean Ϯ SE) among different species were compared with the same age group; different letters within each column and age group indicate a signiÞcant difference among treatments (ANOVA, Tukey HSD test, P Ͻ 0.05).

ϭ Ͻ not control the ratio of hosts to wasps among the asitized by D. longicaudata (F1,48 14.8, P 0.001; Fig. different treatments; thus, percentage parasitism by D. 1A) and laid signiÞcantly more female eggs in unpara- ϭ Ͻ giffardii varied among the tests for each host species sitized than parasitized puparia (F1,38 12.8, P or age (Table 3). Mortality of D. giffardii wasalways 0.001; Fig. 1B). lower in unparasitized C. capitata puparia than in any of the puparia that were previously parasitized in both ϭ Ͻ age groups(young puparia: F3,27 4.8, P 0.05; old Discussion ϭ Ͻ puparia: F4,65 4.5, P 0.05; Table 3). In general, control mortality of unparasitized puparia was also To date, only a few pupal fruit ßy parasitoids have lower than those previously parasitized (Table 3). been evaluated for their potential interactionswith There wasno signiÞcantdifference in mortality of D. egg- or larval-pupal fruit ßy parasitoids (Sivinski et al. giffardii offspring developing on the four secondary 1998, Wang and Messing 2004b). Like the pupal para- host species in either age group (Table 3). sitoids P. vindemmiae (Wang and Messing 2004b) and The adult emergence rate of D. giffardii wasgen- S. gemina (Sivinski et al. 1998), D. giffardii isa facul- erally high, and there wasno difference among dif- tative hyperparasitoid capable of attacking other egg- ferent host species in either age group (young puparia: and larval-pupal fruit ßy parasitoids. ϭ ϭ ϭ ϭ Dresner (1954) reported that D. giffardii could de- F3,27 1.1, P 2.4; old puparia: F4,65 2.1, P 0.09; Table 3). velop equally well on both unparasitized B. dorsalis Preference Between Two Different Host Stages. puparia and puparia previously parasitized by the lar- When provided with a choice, D. giffardii preferred to val-pupal parasitoid F. vandenboschi, although detailed attack older rather than younger C. capitata puparia, information was lacking. Our study showed that D. ϭ Ͻ giffardii reared from secondary host species were both in unparasitized hosts (F1,28 11.6, P 0.001) ϭ smaller and had higher mortality than those reared and hosts parasitized previously by F. arisanus (F1,28 18.4, P Ͻ 0.001; Table 4). Attack on the young puparia from the primary host C. capitata. Because the con- resulted in Ϸ30% egg mortality in both host species. In version of host biomass into parasitoid biomass re- contrast, almost all D. giffardii eggs successfully quires energy, the secondary host should contain less hatched when laid in the older puparia of both species food resources than the primary host. It has been (Table 4). shown that parasitized C. capitata larvae were smaller Preference Between Primary and Secondary Host than unparasitized larvae (Wang and Messing 2003). Species. Dirhinus giffardii preferred to attack unpara- As a result, parasitized C. capitata puparia were smaller sitized host puparia rather than those previously par- than unparasitized puparia. For example, the volume of unparasitized C. capitata puparia (1.108 mm3) was Ϸ1.5 timesthe volume of puparia parasitizedby F. Table 4. Effect of host puparium age on the oviposition pref- arisanus (0.708 mm3) (Wang and Messing 2004b). erence and egg survival of D. giffardii Because D. giffardii was observed to consume almost Host Puparium Host No. Percent Percent all the host resource, it is not surprising that the D. N species age stage dissected eggsdied parasitism giffardii adults that emerged from secondary hosts were smaller than those reared from the primary host. C. capitata 0Ð1 d Larva 85 28.2 15 26.0 Ϯ 5.2a 2Ð3 d Pupa 209 0 15 66.3 Ϯ 4.1b Although there isa positivecorrelation between the F. arisanus 0Ð1 d Larva 41 31.7 15 22.6 Ϯ 3.8a size of hosts and emerged wasps in D. giffardii, there 3Ð4 d Pupa 121 4.1 15 57.9 Ϯ 5.0b is no signiÞcant relationship between individual de- velopmental time and body size in this parasitoid (Ta- Percentage parasitism (mean Ϯ SE) between the two different age groups was compared within the same host species; different letters ble 2). This suggests that D. giffardii growsfasteron indicate a signiÞcant difference between the two age groups (Student large and primary host species than on small and sec- t-test, P Ͻ 0.05. ondary host species, which agrees with the predictions 1318 ENVIRONMENTAL ENTOMOLOGY Vol. 33, no. 5

yet formed. Although D. giffardii could successfully attack the youngest host puparia to some extent, the selection of young hosts comes at a higher cost of juvenile mortality (Table 3). Thus, the selective ac- ceptance of old puparia by D. giffardii isadaptive. Dirhinus giffardii doesnot kill itshostat the time of oviposition, and thus a parasitized host can continue to metamorphose until the parasitoid egg hatches, at which time the ßy larva becomespermanently para- lyzed while the parasitoid larva feeds on it (Dresner 1954). In older puparia, D. giffardii normally lay eggs into the space between the wall of the puparium and the pupa body (Dresner 1954). However, in younger host puparia, if D. giffardii eggshatch before the formation of the host pupae, they are bathed in the host hemolymph, because there is no space between the host body and the puparium wall. High mortality may be caused by either the adult parasitoid feeding on the liquid that exudesfrom a young hostafter it is stung or the immune response of the immature host (dissection found that the surface of some D. giffardii eggshad obviousblack spotswhenlaid in a young host). Only a few facultative hyperparasitoids have been evaluated for biological control, and most of them were not recommended for classical biological control programs(e.g., Ehler 1979, Weselohet al. 1979, KÞr et al. 1993). Among the pupal fruit ßy parasitoids so far evaluated (Sivinski et al. 1998, Baeza-Larios et al. 2002, Fig. 1. Preference and sex allocation by naõ¨ve female Guille´n et al. 2002), most of them, like D. giffardii, P. wasps of D. giffardii between unparasitized C. capitata pu- vindemmiae (Wang and Messing 2004b), and S. gemina paria and puparia previously parasitized by D. longicaudata as larvae. (A) Number of each host species parasitized. (B) (Sivinski et al. 1998), were generalist facultative hy- Percentage of female wasps reared from each host species. perparasitoids. Only a few, such as Coptera haywardi Barsrefer to mean Ϯ SE (n ϭ 25). (Ogloblin), are host-speciÞc (Sivinski et al. 1998). D. giffardii has become well established in several re- gions, including Hawaii (Purcell 1998) and Israel of development modelsfor parasitoidsdevelopingin (Rivnay 1968), since it was released. In Israel, it was a Þxed resource system (Mackauer and Sequeira regarded asan inefÞcient natural enemy, partly be- 1993). It also reßects the plasticity of body growth in cause of its low fecundity (Podoler and Mazor 1981b). this generalist parasitoid that may be an important The actual negative impact by thisparasitoidthrough physiological characteristic that allows it to attack a hyperparasitism in the Þeld has not been documented broad host range (Harvey et al. 1994, Wang and Mess- in Hawaii or elsewhere, because traditional Þeld sur- ing 2004a). veyshave largely ignored pupal parasitoids(Ovruski When provided with a choice, D. giffardii preferred et al. 2000). When it occursin the Þeld, it would likely to attack primary rather than secondary host species reduce the efÞcacy of other fruit ßy parasitoids in and laid more female eggs in the large host species. controlling ßy pests. Although D. giffardii prefersto Attacking the primary host species gave it the advan- attack tephritid ßies rather than their associated para- tage of having large female offspring. This is consistent sitoids and may have a narrow window of potential with theoretical predictions of optimal host selection competition with other parasitoids, this study points and sex allocation, given that there is often a positive out the potential deleteriouseffect of D. giffardii on relationship between female size and reproductive other principal parasitoids and suggests that the use of potential (Charnov and Stephens1988, King and D. giffardii as a classical biological control agent Charnov 1988, Ueno 1998, Napoleon and King 1999, should be avoided, because the parasitoid may disrupt Wang and Messing 2004a). other biological control agents already established. In general, parasitoids attacking quiescent host stagessuchaseggsor pupae prefer to attack younger rather than older hosts (e.g., Wang and Liu 2002). As Acknowledgments host pupae age, internal tissues undergo histolysis, We thank T. Moats for assistance, E. Jarjees and M. W. histogenesis, and differentiation to adult internal or- Johnson for providing D. giffardii, and the USDA-ARS PaciÞc gans and sclerotized appendages, and thus, older host Basin Agricultural Research Center, Honolulu for providing pupae may contain less resources. However, within a fruit ßies and several parasitoids. We also thank two anon- young host puparium of tephritids, the ßy pupa has not ymousreviewersfor helpful comments.Thisresearchwas October 2004 WANG AND MESSING:POTENTIAL INTERACTIONS IN FRUIT FLY PARASITOIDS 1319 supported by USDA-ARS Grant 5853208147 to R.H.M. associated with biological introductions. Annu. Rev. En- Voucher specimens were placed in the Hawaiian Depart- tomol. 48: 365Ð396. ment of Agriculture. ThisisPaper 4682 of the UH College of Mackauer, M., and R. Sequeira. 1993. Patternsof develop- Tropical Agriculture and Human Resources Journal Series. ment in insect parasites, pp. 1Ð23. In N. E. Beckage, S. N. Thompson, and B. A. 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