Beardsley, John W.

Fluker, Sam

Proceedings of the Hawaiian Entomological Society

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Vol. XIX, No. 3, June, 1967 367Coptosoma xanthogramma (White), (Hemiptera:Plataspidae) a New Pest of Legumes in Hawaii1John W. Beardsley, Jr.2 and Sam FlukerUNIVERSITY OF HAWAII, HONOLULUINTRODUCTION jCoptosoma xanthogramma (White), now commonly called the blackstink bug, is the first known representative of the family Plataspidae tobecome established in the Hawaiian Islands. Since the initial discovery ofthis bug in Honolulu during September, 1965, very heavy populationshave been observed on several legume hosts on Oahu, and it is considereda potentially serious pest of cultivated beans and certain ornamental vinesand trees. Nothing on the biology of C. xanthogramma was found in published literature, and relatively little information is available on othermembers of the family Plataspidae.The biological observations reported here were made principally onthe campus of the University of Hawaii, with bugs infesting a maunaloavine, Canavalia cathardica, growing on a fence near our laboratory. Lifehistory data were obtained from bugs caged on the living vine and, in thelaboratory, from confined bugs fed on fresh Canavalia shoots. Some detailsof the life history have not yet been worked out.Coptosoma xanthogramma was described from specimens collected in thePhilippine Islands (White, 1842), where it apparently occurs at least on theisland of Luzon. In addition to Oahu in the Hawaiian Islands, it alsohas been found, apparently recently established, on Iwo Jima in the Volcano Islands, by C.F. Clagg (see February Notes and Exhibitions p.7). The first Hawaiian specimen was taken by the senior author onSeptember 30, 1965, in an ultra-violet light trap on the campus of theUniversity of Hawaii (Beardsley, 1966). This insect apparently is notnormally attracted to light, and it is believed that the original specimenmay have accidentally flown into the light trap from an adjacent maunaloavine which was subsequently found to be infested with these bugs. C.xanthogramma did not come to our attention again until January, 1966,when a resident brought in specimens from an infested jade vine, Strongylodonlucidus, growing at his home near Aiea, Oahu, about 15 jmiles from theUniversity. Through subsequent surveys, scattered infestations werefound throughout the Honolulu area, and in the Kaneohe to Waimanalosection on the windward side of Oahu. These findings indicate thatC. xanthogramma probably became established on Oahu six months to a yearor more before the initial discovery in September, 1965. T0 date (Decem-^ublished with the approval of the Director of the Hawaii Agricultural Experiment Station as Technical Paper No. 857.2Present address: Department of Genetics, University of California, Berkeley.368 Proceedings, Hawaiian Entomological Societyber, 1966) this insect has not been collected on any of the other islands ofHawaii.HOSTS AND DAMAGEIn addition to jade vine and maunaloa vine, C. xanthogramma has beencollected or reported from the following hosts: pigeon pea (Cajanusflavus),lima bean (Phaseolus limensis), several varieties of string beans (P. vulgaris),coral tree (Erythrina sp), shower trees (Cassia spp.) and African tulip-tree(Spathodea campanulata). Except for the African tulip-tree these hostsare all legumes. The insects prefer to feed on the succulent young growthof host plants. The tips of actively growing shoots, young leaves, andflower buds are favored feeding sites. On preferred hosts such as jade andmaunaloa vines very heavy infestations containing up to several hundredindividuals may be found concentrated on the terminal 6 to 10 inches or soof young shoots. Gregarious feeding of this type appears to be a commonoccurrence with both nymphs and adults of C. xanthogramma.On maunaloa vine, heavy infestations of this insect were observed toproduce a general loss of vigor in the host, coupled with some loss of leaves,a marked blossom-drop and reduction in pod-set, and deformation andoccasionally die-back of young shoots. On jade vine, infestations apparently were responsible for considerable blossom-drop in infested flowerpanicles, and for die-back of young vegetative shoots. The type andextent of damage to other hosts has not been reported.LIFE HISTORYThe eggs of C. xanthogramma (Fig. 1) are small, light-red colored, elon-Fig. 1. Egg cluster of C. xanthogramma on Canavalia leaf Photo by P.D. Ashlock.Vol. XIX, No. 3, June, 1967 369gate structures somewhat upturned at the opercular end. The upper surfaces of the chorion are densely and finely pitted. The lower surfaces aresmoother, with relatively weakly developed pitting. The eggs normallyappear partially collapsed rather than fully cylindrical as the sides are concave between a framework formed of four longitudinal ridgelike thickenings of the chorion; a pair of narrow, sharply-defined lateral ridges andmore rounded, broader dorsal and ventral ridges. Eggs average about0.85 mm in length. The conspicuous circular operculum has a peripheralcircle of 22 short, whitish micropylar processes. These are Relieved to servethe dual function of allowing entrance of the sperm at fertilization, andas respiratory organs through which gaseous exchange takes place betweenthe developing embryo and the external environment (Southwood, 1956).The eggs, which are cemented to the surface of the substrate, arealmost always deposited in groups of 3; 2 parallel and the 3rd at right anglesacross the antimicropylar end of the others. Rarely, eggs may be deposited in groups of 2 or 4, but never in 2 parallel rows as is apparently therule with other species of Plataspidae which have been studied (Kershaw,1910; Southwood, 1956). At the time of oviposition the female bugdeposits a small black mass in the center of the group of 3 eggs. This massapparently contains symbiotic microorganisms as invariably the nymphswere observed to feed for a few minutes on this "symbiont pellet" shortlyafter hatching. [For an account of the mechanism of symbiont transferin a related species, Coptosoma scutellatum Geoffrey, see Buqhne (1965) pp.217-220].Hatching is accomplished with the aid of an "egg-buster", a pointedsclerotized spine situated dorsally on the head of the mature embryo.The spine is used to help break open the operculum and is shed as thenymph leaves the egg. Duration of the egg stage from oviposition to hatching was 10 days in all eggs studied, both in the laboratory and caged on thehost vine outdoors. Eggs frequently were found on leaves and shoots ofinfested plants in the open. In the laboratory, eggs were often depositedon the sides of rearing jars, on cloth tops ofjars, or on paper toweling usedto cover the jar bottoms, as well as on host material.First-instar nymphs usually left the empty eggs within a half hour orso after hatching, and wandered about for a time before finding a suitablefeeding site. Newly hatched lst-instar nymphs are mostly orange in colorwith the dorsum of head and thorax light orange-brown. After feeding,the young nymphs take on a greenish tinge. All subsequent nymphalstages are bright green, and closely resemble the color of the young stemsand leaves of the host plant. The nymphs are roughly circular or oval inoutline with a flat venter and a smoothly convex dorsum. Feeding nymphsadhere closely to the surface of the host and those of the 2nd to 4th instars,particularly, are easily overlooked as they resemble small deformities of thehost stems and leaves. The 5th-instar nymphs (Fig. 2) have well-develop-370 Proceedings, Hawaiian Entomological Society2.0Fig. 2. Dorsal view of C. xanthogramma 5th-instar nymph. Drawn by Sybil Seto.ed wing pads which are frequently somewhat darker than the rest of theinsect. The compound eyes are bright red in all nymphal instars. Theteneral adults are pale green, but darken rapidly after a few hours. Ifyoung adults are punctured while still in a teneral condition a drop ofblack body fluid will exude from the wound.Data on nymphal stages were obtained from bugs caged outdoors onmaunaloa vine during April to June. There are 5 nymphal instars, asis the case with Brachyplatys subaeneus (Westwood) and Coptosoma cribraria(Fabricius) (Kershaw, 1910). We began with 50 newly hatched lst-instar nymphs, only 10 of which survived to maturity. The average timeof development for these bugs from hatching to adult was 64 days, witha minimum of 60 days. No data were obtained on adult longevity, thepremating or preoviposition periods, or the total egg production of adultfemales.Vol. XIX, No. 3, June, 1967 371The adult bugs (Fig. 3) are 4.5 to 5.0 mm in length, broadly oval inoutline, flattened ventrally and convex above. They are shining blackwith narrow pale stripes around the sides and posterior portion of thelarge, shield-like scutellum, across the anterior part of the pronotum andbroadly across the anterior margin of the dorsal part of the head. Thereis also a pair of pale transverse dash marks, one on each sicle of the anteriormargin of the scutellum. The venter is mostly dark except for the face andlabrum and the lateral portions of the abdominal segments. The legs andantennae are largely pale, while the compound eyes are red.The adult bugs will often drop from the host plant when disturbed butfrequently take flight before reaching the ground.2.0Fig. 3. Dorsal view of C. xanthogramma adult. Drawn by Sybil Seto.372 Proceedings, Hawaiian Entomological SocietyNATURAL ENEMIESThere appear to be no insect parasites and very few predators whichattack C. xanthogramma in Hawaii. An undetermined anthocorid bugwas once observed to attack and feed on a newly hatched C. xanthogrammanymph on maunaloa vine. However, coccinellid beetles [Coelophora inaequa-lis (Fabricius) ] refused to feed on any stage of C. xanthogramma, even whenconfined for several days without other visible food sources. Althoughno records of insect parasites were found, it is likely that one or moreegg parasites of C. xanthogramma exist in areas where this bug is indigenous,and the discovery and importation of such natural enemies into Hawaiishould be attempted.REFERENCESBeardsley, J.W. 1966. Notes and Exhibitions. Proc. Haw. Ent. Soc. 19(2): 144.Buchner, P. 1965. Endosymbiosis of animals with plant micororganisms. Inter-science Publishers, New York, London, Sydney, xvii+909 pp.Kershaw, J.C.W. 1910. Metamorphoses of two coptosomine Hemiptera fromMacao, Ann. Soc. Ent. d'Belgiqjje 54:69-73.Southwood, T.R.E. 1956. The structure of the eggs of the terrestrial Heteropteraand its relationship to the classification of the group. Trans. Royal Ent. Soc.London 108(6): 163-221.White, H. 1842. In Grays Zool. Misc. 1:80. (Original description of Plataspisxanthogramma). (Not seen)

Coptosoma xanthogramma (White), (Hemiptera: Plataspidae) a New Pest of Legumes in Hawaii

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Coptosoma xanthogramma (White), (Hemiptera: Plataspidae) a New Pest of Legumes in Hawaii

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