Life history and description of immature stages of Neasplota aenigma Friedberg and Mathis (Diptera : Tephritidae) on Erigeron divergens Torrey and Gray (Asteraceae) in southern California
Rd. Goeden, Life history and description of immature stages of Neasplota aenigma Friedberg and Mathis (Diptera : Tephritidae) on Erigeron divergens Torrey and Gray (Asteraceae) in southern California, P ENT S WAS, 102(2), 2000, pp. 384-397
Citations number
28
Categorie Soggetti
Entomology/Pest Control
Journal title
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Neaspilota aenigma Freidberg and Mathis is a multivoltine, oligophagous fru
it fly (Diptera: Tephritidae) developing in the flower heads of Erigeron fo
liosus Nuttall and E. divergens Torrey and Gray in the subtribe Asterinae o
f the tribe Astereae in southern California. This tephritid also has been r
eported in the southwestern United States bordering Mexico from five other
genera and plant species belonging to the subtribe Solidagininae of the Ast
ereae. The egg, first-, second-, and third-instar larvae, and puparium are
described and figured. The dorsal sensory organ is well defined in all thre
e instars. The caudal segment of the first and second instars is ringed by
four stelex sensilla, but by six stelex sensilla in the third instar. In tu
rn, each stelex sensillum in the first instar is ringed by several hemisphe
rical, minute acanthae and one upright, apically rounded acanthus. The mout
h hooks of the first and second instars are bidentate, but in the third ins
tar are tridentate. The integumental petal is fused with the sternal sense
organ in the first instar, but these structures are separate in the second
instar. The ventrally-toothed oral ridges number seven or eight in the thir
d instar, which compares to six oral ridges in three other congeners examin
ed to date. All instars feed mainly on the ovules and soft achenes, but tow
ards the end of the third stadium, the larva tunnels deeply into the recept
acle, sometimes continuing through it into the pedicel. Pupariation occurs
inside the mature flower heads, but no protective cell is formed, as with c
ongeners that overwinter as a prepuparium. Instead, F-1 adults emerge from
flower heads of desert shrubs in late spring (May) and early summer (June),
mate, and complete a summer F-2 generation on late-flowering E. divergens
growing at higher elevations along with E. foliosus (July-August) and a fal
l F-3 generation in different species of late-flowering desert shrubs (Sept
ember-October). Some of these F-2 and probably all F-3 adults overwinter, a
nd those that survive the winter aggregate the next spring (April-May) on p
reblossom host plants to mate and subsequently oviposit. Pteromalus sp. (Hy
menoptera: Pteromalidae) and an unidentified species of Braconidae (Hymenop
tera) are the principal parasitoids of N. aenigma in its Erigeron hosts.