Oenothera pilosella, RAF.

Eiseman, Charles S., 2015, Oenothera pilosellaRaf. (Onagraceae): First Larval Host Record ForDietzella zimmermanni (Gyllenhal) (Coleoptera: Curculionidae: Ceutorhynchinae) andAltica pedipallidaLesage (Coleoptera: Chrysomelidae: Galerucinae: Alticini), The Coleopterists Bulletin 69 (2), pp. 202-204 : 202-204

OENOTHERA PILOSELLA RAF. ( ONAGRACEAE ): FIRST LARVAL HOST RECORD FOR DIETZELLA ZIMMERMANNI (GYLLENHAL) ( COLEOPTERA : CURCULIONIDAE : CEUTORHYNCHINAE ) AND ALTICA PEDIPALLIDA LESAGE ( COLEOPTERA : CHRYSOMELIDAE : GALERUCINAE: ALTICINI)

CHARLES S. EISEMAN Northfield, MA 01360, U.S.A. [e-mail]

On 25 June 2014, I collected several leaves of meadow evening primrose, Oenothera pilosella Raf. (Onagraceae) from a garden in Pelham, Massachusetts, in order to rear larvae of the leafminer Mompha argentimaculella (Murtfeldt) ( Lepidoptera : Momphidae ). I placed them in a sealed plastic vial, and on 6 July, when the first adult moth emerged, I discovered three beetle larvae feeding externally on the leaves. I succeeded in rearing all three, and they proved to belong to two species whose immature stages were previously unknown.

One larva was yellow with many brown tubercles and a dark brown head ( Fig. 1 ). It was approximately 4.5 mm long. It had fed in patches on the lower leaf surface, leaving the upper epidermis intact. Frass was strewn across these patches in elongate, somewhat zigzagging deposits ( Fig. 2 ). As the larva appeared to have finished feeding, I transferred it to a small jar containing a moistened 1:1 mixture of sand and peat, into which it burrowed. On 20 July, an adult Altica pedipallida LeSage ( Chrysomelidae : Alticini) emerged from the soil ( Fig. 3 ).

When LeSage (2008) described Altica pedipallida, nothing was known of its host plants. He noted that specimens near Ottawa, Ontario, Canada were swept from a sphagnum bog and trapped in an old beaver meadow. It would seem that Epilobium L. ( Onagraceae ) is another likely host of this beetle, being a common plant in these habitats. The closely related beetle Altica knabii Blatchley has been collected exclusively from Oenothera L., apart from two other records that are considered incidental. Altica knabii is bivoltine (LeSage 2008).

The other two larvae observed on 6 July were stocky, legless, slug-like, and 3–4 mm long. They were whitish with a pale brown head that was directed downward and not visible when viewed from above. Each larva was largely covered with elongate fecal pellets in a colorless liquid matrix ( Fig. 4 ), similar to the covering worn by larvae of the cereal leaf beetle, Oulema melanopus (L.) ( Chrysomelidae ). They fed by eating ragged holes through the leaf ( Fig. 5 ). On 12 July, one of the larvae had attained a length of 5.5 mm ( Fig. 6 ), and the other was in the process of constructing a thin-walled, parchment-like cocoon, 3.5 mm by 2.5 mm, in the bottom of the vial. Four days later, the pupa had wriggled out of this cocoon ( Fig. 7 ), but the other larva constructed its cocoon between two leaves and remained within it ( Fig. 8 ). By 29 July, two adults of Dietzella zimmermanni (Gyllenhal) ( Curculionidae : Ceutorhynchinae ) had appeared in the vial. They fed on fresh Oenothera leaves I offered them until at least early September, then became inactive and died by early October.

I have previously observed D. zimmermanni adults feeding on O. pilosella foliage in the same garden ( Fig. 9 ). This weevil has been reported from two other onagraceous plants, Epilobium ( Anderson 2002) and Circaea lutetiana L. ( Eiseman 2014). The record of Bidens L. ( Asteraceae ) given by Evans (2014) is based on Blatchley and Leng (1916) and is almost certainly an incidental one, as there was no mention of feeding (A. V. Evans, in litt.). Colonnelli (2004) records this species as “occasionally feeding on flowers of Bidens ”, but no reference is given.

Larvae of most ceutorhynchine species are endophagous. Many mine the stems, crowns, or roots of their host plants; a number of others form galls or feed in flowers or fruits; and a few mine in leaves ( Hoffmann 1954; Anderson 2002; Eiseman 2014). However, at least two species of Perigaster Dietz have habits similar to those of D. zimmermanni , with excrement-covered larvae feeding externally on Onagraceae foliage. Knab (1915) reported rearing Perigaster liturata (Dietz) from such larvae on Oenothera biennis L. Clark (1976) described the habits of the Ludwigia L. feeder P. cretura (Herbst) in detail. Larvae of P. cretura pupate on the upper surface of host leaves in a cell made from a thin layer of hard, transparent, secreted material, augmented with excrement, bits of plant material, and other debris found in the immediate vicinity of the larva’ s last feeding site.

Apart from Dietzella Champion and Perigaster (both Cnemogonini ) and Ranunculiphilus faeculentus (Gyllenhal) (Ceutorhynchini) , which has been found feeding exposed on the apical bud of Consolida regalis Gray (Ranunculaceae) ( Wanat 2011), the ceutorhynchines known to have ectophagous larvae are in the Phytobiini . Several European species of Pelenomus Thomson have slime-coated larvae that feed on the undersides of leaves ( Scherf 1964). Larvae of at least three of these species cover their backs with excrement: Pelenomus quadricorniger (Colonnelli) and Pelenomus waltoni (Boheman) on Persicaria Mill. (Polygonaceae) , and Pelenomus commari (Panzer) on Lythrum L. ( Lythraceae ) and several genera of Rosaceae ( Dieckmann 1972) . Larvae of Pelenomus canaliculatus (Fåhraeus) , Eubrychius velutus (Beck) , and the Holarctic Phytobius leucogaster (Marsham) all feed externally on foliage of Myriophyllum L. ( Haloragaceae ), the latter two species doing so underwater ( Dieckmann 1972). Although Scherf (1964) stated that Pelenomus species may pupate either on their host plants or in leaf litter, according to Hoffmann (1954) and Dieckmann (1972) all of the species mentioned here attach their cocoons to leaves of their host plants. The cocoons are yellowish brown and composed of a secreted material ( Dieckmann 1972), evidently similar to those made by Dietzella and Perigaster .

Figures

Figs. 1–9. Altica pedipallida: 1) Mature larva; 2) Larval feeding damage and frass (Dietzella zimmermanni larva feeding in upper right); 3) Adult. Dietzella zimmermanni: 4) Larva, lateral view; 5) Larval feeding damage; 6) Mature larva, dorsal view, with fecal covering partially removed; 7) Pupa; 8) Abandoned cocoon; 9) Adult.