Epinotia nigralbana (Walsingham)

Eiseman, Charles S., Austin, Kyhl A., Blyth, Julia A. & Feldman, Tracy S., 2020, New records of leaf-mining Tortricidae (Lepidoptera) in North America, with the description of a new species of Grapholita, Zootaxa 4748 (3), pp. 514-530 : 517

Epinotia nigralbana (Walsingham)

( Figs. 7–13 )

Material examined. CALIFORNIA: San Diego Co., Pacific Crest Trail (Barrel Spring: 33.210401, -116.580605), 12.iii.2017, em. 15.iv.2017, C.S. Eiseman & J.A. Blyth, ex Arctostaphylos , # CSE3494 (1♀, CUIC); em. 24.iv.2017, # CSE3556 (1♂, CUIC) .

Hosts. Ericaceae : Arbutus menziesii Pursh , Arctostaphylos hooveri P.V.Wells , A. manzanita Parry , A. montana Eastw. , A. patula Greene , A. virgata Eastw. ( Powell 2006) .

Biology. According to Powell & Opler (2009), E. nigralbana “mines the leaves of madrone and manzanita during winter, maturing in March to May, and adults fly April to August... [Young larvae] mine a thin loop from the leaf margin, defining a circular area, into which they mine digitate extensions after overwintering. Pupation occurs in the mine.” We have found active mines in Oregon on 21 October, by which time the larvae had already begun mining digitate extensions into the semicircular area delineated by the initial arc ( Fig. 7 ). All frass is expelled from a hole at one end of the arc. Our two reared California specimens ( Figs. 12–13 ) were collected as larvae on 12 March; in both cases the leaf was completely mined out at this time (the initial arc still discernable), with oblong fecal pellets scattered throughout ( Fig. 8 ). One larva (CSE3556) pupated within the original leaf, and the pupal exuviae were left protruding from the mine when the adult emerged. The other larva (CSE3494) had tied the edge of a second leaf to the upper surface of the original leaf, without any obvious silk on the surface of either leaf, and had formed a frass-free blotch in the adjacent portion of the fresh leaf ( Fig. 9 ). In captivity the latter larva continued to feed in the new leaf, apparently with a silk tunnel running through the middle of the mine, with frass deposited along either side. When finished feeding it chewed a conspicuous circular exit hole and pupated in a cocoon spun in the bottom of the rearing vial. At the same collection site we found another mine in which the larva had formed an elongate blotch along the leaf margin (proceeding from the initial arc), with a similar pattern of frass flanking a central silk gallery ( Fig. 10 ). There was a similar round hole at the end of this mine, suggesting pupation at least sometimes takes place outside the mine under natural conditions.

Comments. To our knowledge, no illustration or description of the female genitalia of Epinotia nigralbana has ever been published. Heinrich (1926) figured the male genitalia but omitted the female. To that end, we figure the female genitalia here ( Fig. 13 ).

Figures

FIGURES 7–13. Epinotia nigralbana. 7: Backlit view of larva mining in Arbutus menziesii leaf in October; 8: Backlit view of completely mined-out Arctostaphylos leaf in March; 9: Another mined-out Arctostaphylos leaf, tied to a second leaf (below) into which the larva has begun to mine; 10: A third, vacated mine found near the previous two; 11: Pupal exuviae; 12: Reared adult female; 13: Female genitalia.