The larva of Epinotia nisella is best known as a feeder in female catkins of Populus, primarily P. tremuloides Michx. in North America. In Minnesota, adults were reared from larvae boring in current-growth branchlets of P. balsamifera L., with no sign of like infestation in neighboring P. tremuloides, which has thinner branchlets. The behavioral variance is explained as plasticity in feeding biology, a characteristic of insects utilizing host reproductive structures whose abundance is periodic

Miller, William E

English

Valparaiso University

The Great Lakes Entomologist Volume 19 Number 4 - Winter 1986 Number 4 - Winter 1986 Article 3 December 1986 Epinotia Nisella: an Unrecorded Host and Mode of Feeding (Lepidoptera: Tortricidae) William E. Miller University of Minnesota Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Miller, William E. 1986. "Epinotia Nisella: an Unrecorded Host and Mode of Feeding (Lepidoptera: Tortricidae)," The Great Lakes Entomologist, vol 19 (4) Available at: https://scholar.valpo.edu/tgle/vol19/iss4/3 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1986 THE GREAT LAKES ENTOMOLOGIST 205 EPISOTIA lV/SElJA: AN UNRECORDED HOST AND MODE OF FEEDING (I~EPIDOPTERA: TORTRICIDAE) William E. Millerl ABSTRACT The larya of Epinotia nisella is best known as a feeder in female catkins of Populus, primarily P. tremuloides Michx. in North America. In Minnesota, adults were reared from lar.-ae boring in current-growth branchlets of P. balsamifera L., with no sign of like infe~tation in neighboring P. tremuloides, which has thinner branchlets. The behavioral \'ariance is explained as plasticity in feeding biology, a characteristic of insects utilizing host reproductive structures whose abundance is periodic. Epinotia nisella (Clerck), a Holarctic species, is often mentioned in forest insect survey reports. and adults are common in insect collections. The wing pattern s variable (Bradley et al. 1979). Before 1959, E. criddleal1a (Kearfott) was erroneously considered a form of E. nisella in North America (MacKay 1959). The primary larval host is Populus, and the primary larval feeding site is catkins. Only occasionally are Salix. Betula, Alnus, and Acer recorded as hosts. and buds and leaves as feeding ~ites. The currently known Populus h sts in North America are P. fremuloides :\fic~...: .. and P. tricocarpa Torr. & Gray (R. L. Brown. pers. comm.: Forbes 1923; Prentice 1966: Wong and Melvin 1974). The Populus host in Europe is P. tremula L. (Bradle\ et al. 1979. Schefer-Immel 1958, Swatchek 1958). I rearro Epinotia nisella adults in Minnesota from larvae boring in branchlets of Populus balsamifera L. Prior literature on the insect does not mention this host or mode of feeding. Rearing details follow, as well as a suggested explanation for variability in the insect's feeding biology. The reared adults are diagnostically illustrated (Figs. 1-3), and YOueller specimens. including pupal exuviae, are in the insect collection of the University of ~~. St. Paul. During se\'era! growth seasons. mature and near mature P. tremuloides, P. grandi­demGra ~ficlL>;. .. and P. balsamifera growing in mixed stands in Koochiching County, ~~1ota.....ere fdled. and their foliage minutely examined for insects. By 10 June, gall-like ' .... ellings .... ere noticeable on current-growth branchlets of P. balsamifera (Fig.-+1. Cnife,,-red, bost brnnchlets were 2-+ cm Ion!! at this time, as were infested ones. Theswellings smn."IUl1ded mnnels in which solita£)· larvae were feeding. Tunnels did not extend imo the previous y ar's growth. ~ear the mnnel apex was an opening to the outside thn.")UgiJ ....1licb l.a!:oae eje.."ted ITasS. The opening was shrouded by a silken sleeve 1-2 mm long ;:ootaining IDcorpt..T.lled pellets of Crass (Fig. 4b). Before pupation. larvae lined tunnels and openings with silk. In the laboratory. and presumably also in the field, pupati0\1 toof;: pla.."e inside branchlet..,. Before adults ecIosed. pupae pierced these openings and prouu.:Ia:! from them. Tbe length of the longest of 10 tunnels in which larvae rna.ru.red was 1.2 em. Wing panem and color variation in five reared adults matched ~~.:: ,;0{ EIrIOClX'I~•. Cni\cI'5ir~ of \iinnesota. 51. PauL \L'I 55108. 1Miller: <i>Epinotia Nisella</i>: an Unrecorded Host and Mode of Feeding (Published by ValpoScholar, 1986206 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.4 Figs. 1-4. Epinotia nisella reared from Populus balsamifera in Koochiching Co., Minn .. and its larval hahitation. (1) Wings of adult; (2) Male genitalia; (3) Female genitalia; (4 a-c) Infested branchlet; (al swollen area; (b) silken shroud over tunnel opening; (el node separating current and previous year's growth. Figures 20 and 29 of Bradley et al. (1979). No branchlet. infestation was found in neighboring Populus tremuloides or P. grandidentata. Branchlets on these species were smaller in diameter than those of P. balsamifera. Isolated saplings of P. balsamifera as small as 4 m tall were also found infested. The most detailed previous description of Epinotia nisella biology in North America is that of Wong and Melvin (1974). They reported that eggs were laid singly on host buds from mid-June to early July. Larvae hatched in the spring, fed first in buds, then on 2The Great Lakes Entomologist, Vol. 19, No. 4 [1986], Art. 3https://scholar.valpo.edu/tgle/vol19/iss4/31986 THE GREAT LAKES ENTOMOLOGIST 207 female catkin capsules. and finally on leaves. Pupation took place on the ground where larvae dropped or fell along with their habitations. Similar biological observations were reponed for the species in Europe (Bradley et al. 1979. Schefer-Immel 1958). That the E. nisella reared from Populus balsamifera branchlets in Minnesota fed first on catkins seems unlikely because juvenile saplings isolated from older trees were equally infested. The disparate feeding habit and host might be explained in at least three different ways: II) Epinotia nisella is a behaviorally plastic species; (2) different biotypes of E. nisella are involved: or (3) different species of Epinotia are involved. The first possibility seems most likely at present. The main resource utilized by E. nisella larvae, host reproductive structures, is notoriously periodic in forest trees (Matthews 1963). Insects that utilize reproductive structures usually have adaptations for surviving primary resource scarcity. Such adaptations include extended diapause, alternative feeding modes, and alternative host species (Hedlin et al. 1980), any of which may be manifested at any time. The observations reponed here are consistent with the last two adaptations. ACKNOWLEDGMENT I thank R. L Brown. who is currently revising Epinotia, for confinning the identity of the reared E. nisella adults. LITERATURE CITED Bradley. J. D .. W. G. Tremewan, and A. Smith. 1979. British tonrieoid moths. Tonricidae: Olethreutinae. Ray Society, London. 336 pp. F0rbeS. \\'. T. ~f. 1923. The Lepidoptera of New York and neighboring states. Cornell Cni\'. Agric. ExpL Sta. Mem. 68. 729 pp. Hedlin. A. F .. H. O. Yates. D. Cibrhin Tovar, B. H. Ebel, T. W. Koerber, and E. P. ~lerkeL 1980. Cone and seed insects of Nonh American conifers. Canadian Forestry Service. LS. Forest Service, Secretaria de Agricultura Mexico. 122 pp. ~1acKay. ~1. R. 1959. Larvae of the Nonh American Olethreutidae (Lepidoptera). Canadian Entomol. Suppl. 10  338 pp. ~1atthews. J. D. 1963. Factors affecting the production of seed by forest trees: For. Abstr. 24:1-13. Prentice. R. ~1. led.). 1966. Forest Lepidoptera of Canada recorded by the Forest Insect Survey. YoL -1 Canadian Dept. For. Pub!. 1142:543-840. Schefer-ImmeL V. 1958. Ein Massenauftreten von Katzchensch1idlingen an Aspe tPopulus tremula). Anz. Schadlingsk. 31:7-10. Swatchek. B. 1958. Die Larvalsystematik der Wickler (Tonricidae und Carposinidae) . . -\kademie-Yerlag. Berlin. 269 pp. Wong. H. R.. and J. C. E. Melvin. 1974. Insects of aspen catkins in the Canadian prairies. Canadian Forestry Service Northern For. Res. Cent.. Edmonton, Alta., ~OR-X-76. 27 pp. 3Miller: <i>Epinotia Nisella</i>: an Unrecorded Host and Mode of Feeding (Published by ValpoScholar, 1986

\u3ci\u3eEpinotia Nisella\u3c/i\u3e: an Unrecorded Host and Mode of Feeding (Lepidoptera: Tortricidae)

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\u3ci\u3eEpinotia Nisella\u3c/i\u3e: an Unrecorded Host and Mode of Feeding (Lepidoptera: Tortricidae)

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