Clancy, D.W.

Marucci, P.E.

Van Den Bosch, R.

Proceedings of the Hawaiian Entomological Society

ScholarSpace at University of Hawai'i at Manoa

Vol. XIV, No. 2, March, 1951 229NOTES ON NATURAL ENEMIES OF TEPHRITID FLIESDuring November, 1949, five shipments were received from Messrs.Bianchi and Waters, in Bareilly, India, containing 21,883 fruit fly pupariareared from a cucurbit, Luffa sp. In the material bred from these shipments were 67 adults (25 females) of a large Opius indistinguishablefrom Opius longicaudatus (Ashmead) except by its generally paler coloration. The flies from these shipments were identified by Dr. Hardy asDacus curcurbitae Coquillett and D. caudatus F., the majority being theformer. Placed with cucumbers containing melon fly larvae in all instars,these opiines promptly attacked the larvae. Mating and oviposition occurred readily, and numerous progeny were obtained. In a recent test13 mated female Opius produced 389 progeny, of which 213 (55 per cent)were females. The best results in the laboratory were obtained with infested cucumbers. This new Indian Opius (designated temporarily asuOpius No. 5") is therefore a most promising new parasite of the melonfly. Colonies have been turned over to the Board of Agriculture & Forestryfor rearing and liberation.D. W. CLANCY, January 9, 1950.A note presented last October ("Proceedings," 14: 27) called attentionto the sudden increase of Opius persulcatus (Silvestri)1 on Oahu as aparasite of the oriental fruit fly. The data on which that note was basedhave now been analyzed with interesting results.The relative abundance of O. persulcatus and longicaudatus (Ashmead) from various field-collected fruits used in parasite breeding testsduring the five-month period from July to November, 1949, is shown inthe accompanying table. O. persulcatus was first recovered from mountain apple and mixed fruits from Manoa Valley and the University ofHawaii campus, although in numbers far below those of longicaudatus.However, the total percentage of persulcatus steadily increased, from 8.8per cent in July to 91.8 per cent in November. These fruits were collectedmainly in the Manoa, Nuuanu to Kaneohe, and Kalihi areas.The figures in the table also indicate a rather wide variation in thepersulcatus ratio according to the species of host fruit sampled. Infestedguavas are particularly favored, although the ratio shown may be somewhat higher than the actual one because many of these fruits were pickedat an early stage of maturity, before longicaudatus attains its maximumparasitization. The apparent preference of persulcatus for small hostlarvae would therefore favor this species in immature fruits. It is quiteevident, however, that persulcatus is becoming the dominant parasiteof Dacus dorsalis in guavas, which are the most important fruit fly reser-xIt is suspected that the insect which has locally been called O. persulcatus (Silv.), is actually notthat species. These notes may include data on two distinct species under the name persulcatus. Thespecies described on p. 248 as Opius oophilus Fullaway, seems first to have begun to appear in fieldcollections as early as December, 1949, although definite recognition of it by Dr. van den Bosch, asa species distinct from so-called persulcatus, was first announced in May, 1950.—Ed.230 Proceedings, Hawaiian Entomological Societyvoir. O. longicaudatus was still dominant in mature fruits of false kamani(Terminalia catappa) and Surinam cherry during September and October, and also from mock orange (Murraya) and Chrysophyllum mono-pyrenum at Foster Garden in December.Table 1.—Relative abundance of Opins persulcatus and O. longicaudatus in field-collected fruit on Oahu, 1949Month Host FruitJuly GuavaMountain appleSurinam cherryMixed fruitsTotalAugust GuavaRose appleTotalSeptem- Guavaher Surinam cherryFalse kamaniMixed fruitsTotalOctober GuavaSurinam cherryFalse kamaniMixed fruitsTotalNovem- Guavaber Mixed fruitsTotalNo. oftests182152653832551355503256010111No. of O.longicaudatus271,31118362,1752378161,0537611565531,2362,7063531783726997219423Opius persulcatusNumberreared0204072111431803231,08370203491,5223,13454271173,3322590259Percentage013.501.08.837.618.124.258.731.03.522.036.089.823.36.862.977.493.2091.8[Dr. van den Bosch commented that O. persulcatus is bred most commonly from fruits taken from the trees, while longicaudatus is primarilya parasite of maggots in fallen fruits.]D. W. CLANCY, February 13, 1950.During November and December, 1949, numerous female Opius longicaudatus were observed inserting their ovipositors into melon-fly-infestedfruits of Momordica balsamina. Since laboratory tests had indicated thatlongicaudatus is unable to develop in Dacus cucurbitae, these fruits weresystematically collected and placed over sand for rearing records. Although the 51 fruits thus collected produced a total of 109 adult D.cucurbitae, not one parasite issued from any of the puparia. It appears,therefore, that melon fly is immune to parasitization by O. longicaudatus,even though it may be subject to attack in nature.P. E. MARUCCI, February 13, 1950.During the past several months there has been a remarkable increasein parasitization of oriental fruit fly larvae infesting guava fruits on Oahu.This is especially true of the Waimanalo-Kailua area where gauva hasVol. XIV, No. 2, March, 1951 231been fruiting heavily for about two months. At one collecting point nearWaimanalo, parasitization jumped from 14.5 per cent on May 5, to 86.6per cent on June 13. During this same period there has been a generaldecrease in infestation of guavas. There is little doubt that increasedabundance of guava fruits would initially have some effect of reducinginfestation. However, it is quite probable that parasites, along with othermortality factors, are exerting a strong depressing influence on the fruitfly population.At most of our collecting stations Opius persulcatus2 has been the mostabundant parasite, and at several places large numbers of its males havebeen observed swarming over guava foliage and undergrowth. Similarswarming of male O. longicaudatus has been reported several times, butprior to this spring swarming of persulcatus has not been noted.O. longicaudatus continues to play an important role in the parasitization of Dacus dorsalis. It is particularly noteworthy that large numbers ofthis parasite were recovered from one of the Manoa collection stations.On our recent visit to this site we observed swarms of males hoveringover the vegetation.An increasingly important parasite is the so-called "Waikane Opius"3which until very recently had been considered a color phase of persulcatus, but is now believed to be a distinct species. This parasite has beenspreading rapidly on windward Oahu and is now generally distributedover that area. In addition, it is very abundant in the region of Poamohoin central Oahu. Specimens have been recovered from Manoa Valleyand other scattered localities, and from several places on Hawaii. It hasactually become the most abundant species at some of the windward Oahucollecting stations, notably Waikane, Makaua and Kahana.In addition to the parasites just discussed, a fourth, Opius incisi Sil-vestri, has been recovered in small numbers. This species has seldom occurred in our guava collections, but small numbers are frequently obtained from Surinam cherries, and a few from rose apples and guavascollected on Hawaii. Although other parasites have been released, nonehas been recovered in our investigations.ROBERT VAN DEN BOSCH, July 10, 1950.For some time numerous earwigs have been observed in certain areasliving beneath infested, rotting fruits on the ground, which appeared tobe subsisting, at least in part, on fruit fly larvae. To study their foodhabits, several immature earwigs were collected during May and isolatedin tin salve boxes containing larvae of Dacus dorsalis, which they readilyattacked and devoured. They also attack and devour the contents of thefly puparia. On several occasions earwigs were also seen in the field feeding on larvae of D. dorsalis in guavas, and on those of D. cucurbitae incucumbers—definite evidence of their predatory habits.Earwigs were particularly abundant last month in a gulch near Kane-ohe, Oahu, where the ground was covered with rotting guavas. Their2 See footnote 1, p. 229.3 Opius oophilus Fullaway; see pp. 248 and 251.232 Proceedings, Hawaiian Entomological Societynumbers are indicated by the finding of one or more earwigs in 53 of100 fruits examined at random. Also, fruit fly larvae were noticeably lessnumerous in the guavas containing the earwigs.Laboratory feeding tests are underway with immature earwigs of varioussizes, to determine their feeding capacities. Battery jar units were set upwith artificially infested guavas containing known numbers of D. dorsalislarvae; one series received earwigs, the other was reserved as controls.Feeding records are obtained periodically by comparing the survivingfruit fly populations in each series of jars. At the end of the first 13 daysthere was an indicated destruction of nearly 50 larvae per earwig, showing that these insects are potentially important predators of fruit flies.Two species are involved; they are tentatively identified as Anisolabiseteronoma Borelli and Euborellia annulipes (Lucas).P. E. MARUCCI, September 11, 1950.Although many thousands of a new Opins* from northern India, aparasite of the melon fly, have been liberated during the past eightmonths, only a few adult parasites have been recovered. The apparentfailure of this species to become established is extremely puzzling sinceit breeds readily in melon fly in the insectary. On August 18, 25 femalesof this Opius, reared from puparia of D. cucurbitae originating in India,were released near a Momordica balsamina vine behind the laboratory.On September 24 several adults of this parasite were seen ovipositing inthe small Momordica fruits which were then collected and placed ina rearing jar. From 46 fruits 302 melon fly puparia were obtained, whichlater yielded 26 (9 females) "Opius No. 5/' and 12 Opius fletcheri Sil-vestri. These rearings indicate that the new melon fly Opius can reproduce in Hawaii under natural conditions, and that it should eventually become established here. Its progress is being followed by periodicfruit collections from the Momordica vine. Females of O. longicaudatus,O. persulcatus (so-called) and O. oophilus Fullaway were also seen tooviposit in Momordica fruits, but only a single adult of the last-namedspecies has been recovered to date.P. E. MARUCCI, November 13, 1950.During the past several months investigations of multiple parasitismin oriental fruit fly larvae have been made. (Multiple parasitism is thesimultaneous parasitization of a single individual host by two or morespecies of primary parasites.) So far studies have been limited to the interrelationships of Opius oophilus Fullaway5 and O. persulcatus (the tax-onomic status of the last-named insect is in doubt), and relatively few larvae have been examined. However, it is felt that the findings to date warrant mention at this time. As reported elsewhere in these "Proceedings,"O. oophilus attacks the eggs of Dacus dorsalis, and the so-called persulcatusattacks the first instar larvae. This has facilitated our studies because*This is a species similar to Opius longicaudatus, but with different host preferences. It is described as Opius watersi Fullaway, on p. 249 of this issue of the "Proceedings." It has been knownlocally as "Opius No. 5."5 For description and biological notes of this species see pp. 248 and 251.Vol. XIV, No. 2, March, 1951 233we have been able to detect easily the small parasite larvae, the eggs orthe egg shells in the first instar and small second instar host larvae. Although first instar larvae of the two parasites are, for practical purposes,indistinguishable, no difficulty has been found in determining the species,when larvae are observed, because of the distinctive egg shells associatedwith them in the host. Eggs of the two parasites differ greatly in sizeand shape, and identification of the egg shells make it possible to recognize cases of multiple parasitism. Fruit fly larvae used in these studieshave been from both naturally (field) infested fruits and artificially(laboratory) infested fruits. Similarly, parasitization has been bothnatural and artificial. Examination has been restricted to first instar andearly second instar host larvae.So far 158 fruit fly larvae have been examined. Of these, 37 were un-parasitized, 79 contained O. oophilus only, 12 contained O. persulcatusonly, and 30 were multiparasitized (contained both parasite species).Because of superparasitism (the parasitization of an individual host bymore larvae of a single parasitic species than can mature in that host)the 12 hosts with persulcatus only, actually produced 14 parasites. Forthe same reason the 30 multi-parasitized hosts contained 36 persulcatuseggs. Because the great majority of host larvae were parasitized by oophilus, many cases of superparasitism by this species resulted; but this factorhas no bearing on the findings presented here and is not covered in thisdiscussion.The most important fact resulting from the work so far is that in allcases of multiple parasitism, eggs of persulcatus have shown no development; most of these eggs appeared to be in various stages of degeneration,several being partially or completely collapsed. On the other hand, in allcases where only persulcatus was found, they were either well developed,healthy eggs or first instar larvae. These findings indicate that the presence of O. oophilus has an adverse effect on the eggs of persulcatus in thesame host, and that this effect is possibly physiological rather than mechanical. It is emphasized again that these studies are in a very early stageand much more work is needed to gain a better understanding of theproblem.ROBERT VAN DEN BOSCH, December 11, 1950.The progress of the introduced enemies of the oriental fruit fly hasbeen remarkable on the island of Oahu, but on the other islands of theTerritory, probably because fewer parasites were liberated, progress haslagged. However, during the past year parasitism has risen sharply on theisland of Hawaii, and percentages of parasitization there now comparefavorably with those on Oahu.The first collections this year on Hawaii were made over several daysin late February and early March. These consisted of 24 collections containing 684 guava fruits, from which 3,274 flies and parasites were obtained, with a total parasitization of 32.5 per cent. Of this total 5.2 wereOpius longicaudatus, 27.3 were the so-called O. persulcatus, and 0.03per cent were O. incisi. Opius oophilus was not recovered from this series.In June 356 guavas were collected at 13 places; 2,714 flies and parasites234 Proceedings, Hawaiian Entomological Societyemerged and the parasitization from this series was 37.8 per cent. Of thisfigure, longicaudatus parasitized 3.1 per cent, persulcatus 33.1 per cent,and incisi 0.1 per cent. O. oophilus, which was recovered for the firsttime, parasitized 1.5 per cent.The most recent collections were made in October, and show a remarkable increase in parasitization. From 460 guavas from 12 localities, 825flies and parasites were reared; the parasitization totalled 71.5 per cent.Of this total 0.8 per cent was by longicaudatus, 57.4 per cent by the so-called persulcatus, and 13.3 per cent by oophilus. No incisi were recovered.Not only is the high percentage of parasitization interesting, the sharpincrease in oophilus is also noteworthy.ROBERT VAN DEN BOSCH, December 11, 1950.The increase of the Mediterranean fruit fly in some areas where Dacusdorsalis is now at a low ebb, suggests some interesting possibilities. Shouldthe present trend continue, Ceratitis capitata might conceivably becomethe major pest of fruits, because the parasites attacking it are less effective than those which attack dorsalis. The possibility, therefore, thatthe parasites of the oriental fruit fly might attack Ceratitis becomes ofsome importance. About a year ago ("Proceedings," 14:27) we reportedthe experimental rearing of Opius longicaudatus on Ceratitis, and aninstance apparently involving these two insects in naturally infestedpeaches on Maui. Last August peaches from Kula, Maui, collected byMr. Maehler, at 3,700 ft., produced 4,897 adult Ceratitis, 18 D. dorsalis,1,091 Opius longicaudatus and 23 so-called O. persulcatus; these rearingsadded weight to the belief that longicaudatus is actually developing inCeratitis in the field in the Kula district.A series of comparative laboratory tests was then run to determine theextent to which Ceratitis may serve as host for the several recently introduced parasites of Dacus dorsalis. In these tests papayas and guavaswere separately infested with Ceratitis and D. dorsalis, and then exposedsimultaneously to O. longicaudatus, the so-called O. "persulcatus," andO. oophilus Fullaway (this species is described on page 248 of this issue ofthe "proceedings") . Fruits used with O. longicaudatus contained largerlarvae; those offered to "persulcatus" contained older eggs and newlyhatched larvae; and oophilus tests were conducted with newly-depositedeggs of both Ceratitis and D. dorsalis. There were four replicates in thelast-named series, and five with each of the other species. The results aresummarized as follows:Parasite SpeciesOpius "persulcatus"longicaudatus....oophilusFrom Dacus dorsalisNumberpupariaobtained1,0322,320851Per centparasit'd52.952.618.7Per centfemales31.125.035.6From Ceratitis capitataNumberpupariaobtained528838483Per centparasit'd44.323.49.2Per centfemales27.812.516.6Vol. XIV, No. 2, March, 1951 235It will be noted that all three parasites were successfully reared on C.capitata, though in varying degree. O. "persulcatus" appears best adaptedto this host, reproducing on it nearly as readily as on Dacus dorsalis,while both longicaudatus and oophilus were only about half as effectiveon Ceratitis as on dorsalis. Although these tests are not necessarily indicative of a similar relationship in nature where other environmentalfactors are operative, the possibilities are encouraging.D. W. CLANCY, December 11, 1950.

Notes on Natural Enemies of Tephritid Flies

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Notes on Natural Enemies of Tephritid Flies

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