THE BIOLOGY AND IMMATURE STAGES OF (FABRICIUS) (COLEOPTERA: CHRYSOMELIDAE)1- 2

GARY L. PIPER3 Department of Biological Sciences, Kent State University, Kent, Ohio 44^40

PIPER, GARY L. The Biology and Imma- of phytophagous . Between 196S ture Stages of Zygogramma suturalis (Fabri- cius) (Coleoptera: Chrysomelidae). Ohio and 1970, the biology of several coleop- J. Sci. 75(1): 19, 1975. terous associates were thoroughly inves- The life history of Zygogramma suturalis tigated both in the field and laboratory, (Fabricius), a bivoltine species associated and the results of a study on a foliage with the ragweeds, Ambrosia spp., was studied in Northeastern Ohio during 1969 feeding member of this complex and 1970. Overwintered adults became Zygogramma suturalis is reported. active and began feeding in early May. The genus Zygogramma Chevrolat Eggs were laid in clusters of two or three on the undersides of young leaves. Re- (Chrysomelidae: ) is rep- cently hatched larvae fed gregariously on resented by 99 species in the Nearctic and the same leaf on which the eggs had been Neotropical regions (Bechyne, 1952). laid. However, second, third, and fourth In the United States, there are 14 widely instars were less gregarious and dispersed randomly to new leaves when the initial distributed species (Arnett, 1968). Aside food supply was exhausted. Pupation oc- from adult taxonomic descriptions and curred in the soil beneath the host plant. local-faunistic studies, literature on the The mean duration of the developmental genus is sparse, probably because of the stages (in days) was: egg 5, larval 15-18, prepupal 7-8, pupal 6-9. Descriptions of lack of knowledge on larval feeding the egg, four larval instars, and pupa are habits of most of the essentially non- presented for the first time. economic species. Brisley (1925) re- ported on the larval feeding behavior of Z. exclamationis (Fabricius) on sun- Each species of weed has its own flower, Helianthus petiolaris Nuttall. population, just as each economic plant Douglass (1929) collected the beetle from has an associated complex of insects, in- H. lenticularis Rydberg as well as H. cluding pest species, which may reduce petiolaris. Walker (1936) presented de- the yield or commercial value of the plant. tailed life history information on Z. Unlike the economically beneficial plants, exclamationis and noted its occurrence on many important weeds have been studied H. annus L. in Kansas. According to poorly regarding the insects utilizing them Blatchley (1910), adults of Z. suturalis as hosts. A plant pest in this category is (Fabricius) were found on ragweed in common ragweed, Ambrosia artemisii- low, moist places during the spring and folia L. (Compositae). In addition to on goldenrod flowers, Solidago spp., in being a serious agricultural weed, it is the fall. Douglass (1929) collected Z. well-known as an aeroallergenic pollen- suturalis from weeds in July and August producer responsible for summer and fall and provided distributional and seasonal hayfever throughout much of the United information for five additional Zygo- States. gramma species. Hughes (1939, 1944) In Northeastern Ohio, the common found Z. suturalis larvae feeding on the ragweed supports a diverse assemblage leaves of Ambrosia spp. and recorded the beetle from 27 Ohio counties. 1Manuscript received February 15, 1974 (74-3). 2A portion of a thesis submitted to the Kent MATERIALS AND METHODS State University Graduate School in partial Observations on the biology of Zygogramma fulfillment of the requirements for the degree suturalis were made in 1969 and 1970 in North- of Master of Arts. eastern Ohio, primarily in Portage County 3Present address: Department of Entomol- within a three-mile radius of Kent. Adults ogy, Texas A&M University, College Station, either were swept from the host plants with a Texas 77843. standard aerial insect net or were collected in- 20 GARY L. PIPER Vol. 75 dividually in small vials. Eggs were found by There were two generations per year examining the lower surfaces of young rag- weed leaves. Entire leaves infested with Z. in Northeastern Ohio. Larvae of the suturalis larvae were clipped from plants, first or spring generation began feeding placed in large plastic petri dishes, and trans- in mid-May or early June and most ported to the laboratory for further study. reached maturity by early July. Larvae Prepupae and pupae were obtained by searching the soil beneath the host plants. of the second or late summer generation Rearings were maintained in the laboratory were evident during the first two weeks at room temperatures of 20°-25°C, 50%-60% of August. The adults overwintered in RH, and a 12/12 hr photoperiod. Adults were soil or under debris. confined to baby food jars (9x6 cm) which had their bottoms removed. The jars were in- Laboratory reared adults lived about verted and the top of each was pressed into the two months, with the females generally bottom of a small plastic petri dish (5.5 x 1.3 outliving the males. Adults of both gen- cm) containing moist peat moss. The open erations fed ravenously upon leaves of the bottom of the jar was covered with a layer of fine mesh nylon netting. Entire ragweed plant, but second generation adults were plants, ranging from 8-10 cm in height, were observed feeding upon the involucres of placed in the rearing jars to serve as food and the pistillate flowers. If approached or oviposition material, with new plants and water disturbed while on the plant, the added periodically. As eggs appeared, they were transferred to small petri dishes contain- fell to the ground and feigned death. ing moistened filter paper discs. Larvae were No complex courtship behavioral pat- reared individually in petri dishes and were tern was observed in Z. suturalis. The supplied with fresh leaves at 48-hour intervals. Pupae were held in petri dishes containing male mounted the female from behind by moist peat moss. moving directly forward and onto her Samples of the developmental stages were dorsum. The forelegs rested upon the preserved. Eggs were preserved in KAAD female's elytra, while the tarsal claws of and studied directly in the preservative. the middle pair of legs grasped the Larvae and pupae were killed in hot water, elytral margins (fig. 1). The hindtarsi then preserved in 70% alcohol. For study of gross morphological structures of larvae and were rubbed rapidly in a sideways fashion pupae, the specimens were removed from the across the female's last abdominal ster- alcohol and placed in water. Minute morpho- nite preparatory to copulation. After logical structures of the larvae such as head several of these sequential rubbing move- capsules, mandibles, and spiracles were dis- sected out and studied in temporary glycerine ments, the aedaegus was extruded and mounts. Measurements of the immature stages intromission occurred. The female gen- were made with an ocular micrometer. The erally remained quite passive during ocular grid method, described by Steyskal copulation. Copulation lasted from five (1950), was used in making the drawings. minutes to well over an hour, and fre- LIFE HISTORY quently copulation occurred several times Zygogramma suturalis has been re- during a two to three hour period. Mat- corded from Maine, south to Mississippi, ing was seen most commonly during the and west to Arizona. Adults are broadly late morning and early evening in nature, oval, convex, and dark brown, usually but it was initiated at various times dur- with a faint bronze or greenish luster; ing the day in the rearing jars. each elytron with base, lateral margin, The preoviposition period was not de- interval between second and third striae termined. Daily egg production ranged (sometimes also interval between fourth from 0-37 per female, with the average and fifth striae) and basal part of epi- of 13 per day. Total egg production per pleura a pale yellow. female ranged from 145-563, the average Hughes (1944) gave the earliest and being 165. The length of the oviposition latest Ohio seasonal records for this spe- period varied from 22-42 days with an cies as April 14 and September 24. In average length of 33 days. Eggs were the Kent area however, the adults were deposited in clusters of two or three on taken from May 4 to September 30. the underside of young ragweed leaves Adults began to emerge when ragweed usually near the leaf tip (fig. 2). Oc- seedlings were only 2-5 cm tall. Adult casionally, eggs were laid on the upper populations remained large throughout surface of leaves. Eggs were anchored June, July, and August, but declined firmly to the substrate by a clear mucila- steadily during September. ginous secretion and projected out from No. 1 BIOLOGY OF Z. SATURALIS 21

FIGURES 1-5. Zygogramma suturalis 1. Mating position of adults; 2. Egg arrangement on leaf underside; 6. first and second instar feeding position and damage; 4 Pupa ventral view; 5. Pupa, lateral view.

the leaf at about a 45° angle. They were ing, the larvae resembled small spheres found from the middle of May to late or pellets and concealed themselves in August. The incubation period of eggs leaf folds. When exceedingly abundant, held under laboratory conditions was the mature larvae inflicted substantial five days. Viability of laboratory-laid damage and often completely defoliated eggs exceeded 98%. portions of a plant, but such instances Within the eggs, the first instars initi- were observed infrequently in the field. ated a series of contractile movements If molested while feeding, third and which succeeded in rupturing the chorion fourth instars simultaneously regurgi- in two places. Emergence occurred tated undigested foodstuffs, which rapidly through these slits and the complete engulfed the head, and ejected from the process lasted 15-20 min. Recently anus a comparatively large quantity of hatched larvae actively fed in groups of dark brown fluid. Eisner and Meinwald from two to four on the undersides of (1966) proposed that such exudates pre- leaves, most commonly on the young, sumably produce an offensive odor or succulent, unfolding leaves below the taste, causing predators to desist from terminal bud. Second, third, and fourth further attack. Possession of such a instars tended to be less gregarious in behavioral mechanism has considerable their feeding habits, and often the larvae survival value for the leaf-feeding larvae. on any one leaf represented several dif- No parasitism of or predation on the im- ferent instars (fig. 3). Older larvae be- mature stages was recorded in the field gan to disperse randomly when the initial during the study, but this does not pre- food supply was exhausted. When feed- clude the possibility of its existence. The 22 GARY L. PIPER Vol. 75 first larval stadium was completed in four 1 or 2. Pronotum weakly sclerotized; or five days, the second in three or four not distinct; all setae confined to anterior, days, the third in three or four days, and posterior, and lateral margins. Pro- and the fourth in four or five days. Duration postdorsal folds of thoracic and abdomi- of the larval period ranged from 15-18 nal segments not distinct; sucking disc days. extremely protuberant. Spiracles uni- A fourth instar ceased feeding toward form in size, except mesothoracic which the end of its larval development. The are larger. larva became positively geotactic and Second Instar. Similar to first instar descended to the ground, whereupon it except in following characters. Length burrowed 2-8 cm into the soil. Having 2.10-2.97 mm, head width 0.66-0.76 mm. reached a suitable depth, the larva pushed Color pale yellow-orange. and compacted the surrounding soil until Third Instar. Similar to fourth instar an oval chamber was formed. The pupal except in following characters. Length cell was rough externally and smooth in- 3.30-4.62 mm, head width 0.99-1.12 mm. side. The prepupal stage began im- Fourth Instar (fig. 6). Length 4.90- mediately after the formation of the 6.27 mm, head width 1.32-1.54 mm. earthen cell. The fourth instar trans- Pale yellow, shining; integument thin; formed into a prepupa without molting. sparsely clothed with fine white setae. It became more rigid and globular in Form cyphosomatic; sides curved, nar- shape but retained all the morphological rowed anteriorly from abdominal seg- features of the larva. The prepupal ment 1 and posteriorly from segment 6. stage lasted seven to eight days, i.e. from Head exserted, hypognathous; head cap- the time of chamber formation to the sule golden yellow, rounded and some- molt into the pupa. what shining. Distinct V-shaped epi- The pupal periods of 148 individuals cranical suture (fig. 7); epicranial arms lasted six to nine days, with most pupae curving ventral to lateral ocelli, ending producing adults in seven days. After just posterior to antennal sockets. Frons ecdysis, the teneral adult remained under- with 10 setae, 2 just ventral to juncture ground for two or three days. It then of frontal suture and coronal suture, 4 in escaped from the pupal cell by burrow- a semi-circular row ventral to those, and ing upward thru the soil. Upon emer- 4 widely spaced setae in a row dorsad gence, the adult was lighter in color than clypeus. Antennae prominent; 3-seg- normal and quite soft. Within six to mented; segments 1 and 2 equal in length, eight hours after emergence, the beetles 2 with a supplementary process, 3 shortest were fully pigmented and sclerotized. and tapered. Twelve lateral ocelli; a mid-lateral group of 8 (4 on each side of DESCRIPTIONS OF IMMATURE STAGES head), and a ventral pair on each gena. Egg (fig- 11). Length 1.45-1.65 mm, Lenses raised and clear with black pig- maximum width 0.56-0.66 mm. Sub- ment bodies beneath. Genae sparsely shining, yellowish-orange. Oblong-oval, setose. Distinct fronto-clypeal and cly- slightly tapered toward the ends, ends peal-labral sutures present; clypeus 5-6 bluntly rounded. Chorion asperate, times longer than wide with 6 well de- sculptured into raised reticulations form- veloped setae. Labrum 4 times longer ing numerous hexagonal cells, sculpturing than wide with a deep mid-ventral inci- uniform throughout. Micropyle located sion; 4 setae, 2 on each side of incision; terminally. anterior margin beset with 8-10 bristly First Instar. Similar to fourth instar setae. Mandibles (fig. 9) palmate with except in following characters. Length 5 distal teeth; teeth reddish-brown, 1.45-1.91 mm, head width 0.53-0.59 mm. darker than rest of mandible; ectal sur- Color pale orange. Form slightly cypho- face bearing 2 setae. Maxillary palpi somatic, somewhat fusiform. All cepha- (fig. 8) 3-segmented; segment 3 longer lic, thoracic, and abdominal setae longer than 1 or 2, 1 shortest. Ventral surface than those of third and fourth instars; all of segment 2 with 1 sensillum placodeum; setae arising from distinct tuberculate tip of segment 3 invested with 14-15 bases. Antennal segment 3 longer than sensilla basiconica. Mala well developed, 0.50 FIGURES 6-11. Zygogramma suturalis. 6. Lateral habitus of fourth instar; 7. Head capsule of fourth instar, frontal view; 8. Right maxilla of fourth instar, ventral view; 9. Right mandible of fourth instar, ental view; 10. Abdominal spiracle of fourth instar; 11. Egg. All measurements indicated by scale lines are in millimeters. An, antenna; CP, clypeus; EA, epicranical arm; ES, epicranial suture; LB, labrum; Ma, mala; Mp, micropyle; MP, maxillary palpus; SD, sucking disc; Sp, spiracle. 24 GARY L. PIPER Vol. 75 prominent. Labial palpi 2-segmented; Metanotum glabrous except for row of segment 2 longer than 1; tip of segment 2 10 setae on posterior margin. Elytra and with 6-7 sensilla basiconica. Ligula, wings hyaline, extending to anterior mar- mentum, and submentum setose; hypo- gin of abdominal segment 7. Posterior stoma glabrous. Prothorax, mesothorax, margins of lateral tubercles each bearing metathorax each with pair of legs; legs 3 setae. Abdominal terga 1-6 each with 4-segmented, terminating in sclerotized a marginal row of 16-18 setae. Tergite tarsunguli; legs setose ventrolaterally. 7 short, bluntly V-shaped with 12-14 Pronotum weakly asperate, shining; mod- setae along posterior margin. Tergite erately setose. Prosternum with pre- 8 short, concealed beneath 7; 8 marginal sternum and eusternum protuberant; setae. Tergite 9 tapered, visible from glabrous. Meso- and metanotum divided above; ending in a sclerotized spine; 10 into pro- and postdorsal folds; each fold marginal setae. Sterna glabrous, shin- bearing transverse row of setae. Meso- ing. Legs with 3 setae near apex of each and metathoracic pleura with epimeron femur; hind femora extending to abdo- and eusternum; each with 3-4 setae. minal segment 6; tarsi directed posterad. Meso- and metasternum shining; euster- Spiracles present on abdominal segments num of each sparsely setose. Abdominal 1-8; gradually decreasing in diameter segments 1-7 each with 2 dorsal folds; posteriorly; annular, peritremes raised pro- and postdorsal folds with transverse above general level of cuticle; heavily row of 12-14 minute setae; group of 3 sclerotized. setae dorsad each spiracle; subspiracular tubercles present on segments 1-8, each Acknowledgments. I wish to acknowledge the assistance of the following individuals: Dr. T. S. tubercle bearing 3-4 setae. Sterna 2-9 Cooperrider, Department of Biological Sci- with marginal transverse row of fine setae; ences, Kent State University, and Dr. R. E. each sternite with 2 "prolegs", 1 on each White, Systematic Entomology Laboratory, side of meson. Segment 9 tapered with USDA, for confirming identifications of the plant and beetle, respectively, and Dr. J. A. 12 scattered long setae. Segment 10 Wilcox, New York State Museum and Science short; 10-12 scattered setae; venter of Service, for providing distributional informa- segment with 2 fused anal prolegs which tion on the chrysomelid. form a sucking disc. Spiracles annular; LITERATURE CITED peritremes black, heavily sclerotized (fig. Arnett, R. H., Jr. 1968. The beetles of the 10). Paired spiracles on mesothorax and United States. Amer. Entomol. Inst., Ann abdominal segments 1-8; mesothoracic Arbor, Mich. spiracle largest; abdominal spiracles grad- Bechyne, J. 1952. Nachtrage zu den Kata- logen von Blackwelder und Junk-Schenkling ually decreasing in diameter posteriorly. der neotropischen echten Chrysomeliden. Pupa (figs. 4, 5). Length 4.20-5.04 Entomol. Arb. Mus. G. Frey Tutzing Muen- mm. Body closely resembling form of chen 3: 1-62. adult in size, shape, and in proportions of Blatchley, W. S. 1910. An illustrated de- scriptive catalog of the Coleoptera or beetles the cephalic and thoracic appendages; known to occur in Indiana. Nature Publ. exarate; color pale yellow. Head with Co., Indianapolis. vertex not visible from above; group of Brisley, H. R. 1925. Notes on the Chryso- 12 setae dorsad each ocellus; 2 setae near melidae (Coleoptera) of Arizona. Trans. each antennal socket. Clypeo-labrum Amer. Entomol. Soc. 51: 167-182. Douglass, J. R. 1929. Chrysomelidae of Kan- bluntly triangular; labrum with 2 setae. sas. J. Kans. Entomol. Soc. 2: 1-15. Antennae arising laterad ocelli, curved Eisner, T. and J. Meinwald. 1966. Defensive and directed posterolaterally, terminat- secretions of . Science 153: 1341- ing alongside the mid-femora. Eyes 1350. Hughes, J. H. 1939. Chrysomelidae or leaf slightly convex, glabrous. Lateral mar- beetles of southeastern Ohio. Unpub. M.A. gins of pronotum projecting forward; Thesis. Ohio Univ. posterior margin bisinuous; pronotum 1944. List of the Chrysomelidae in with a shallow, median, longitudinal Ohio. Ohio J. Sci. 44: 129-142. Steyskal, G. C. 1950. An easy way to make groove; densely setose. Mesonotum entomological drawings. Entomol. News 61: smooth, glabrous; scutellum protuberant 137-139. with 6 setae; anterior margin of meso- Walker, F. H., Jr. 1936. Observations on sun- pleuron with a large, oval spiracle. flower insects in Kansas. J. Kans. Entomol. Soc. 9:16-25.