Acerocnema breviseta, (Zetterstedt, 1846) (Zetterstedt, 1846)

Ozerov, A. L. & Krivosheina, M. G., 2024, To the biology of Acerocnema breviseta (Zetterstedt, 1846) (Diptera: Scathophagidae), with description of immature stages, Russian Entomological Journal 33 (3), pp. 401-406 : 402

Results

BIOLOGY. Adults of both sexes ( Figs 1–3 ) are found during spring (last April – early May). The flies are encountered in places with Corydalis solida (L.) Clairv., 1811 (fam. Papaveraceae ) ( Figs 4–6 ).

The life history of this species can be summarized as follows: adults emerge from overwintering pupae from the middle of April and, after mating, lay eggs to seeds of Corydalis solida from the late of April to early of May. Larvae apparently penetrate the seed of Corydalis solida ( Fig. 4 ) to consume its contents through the micropyle ( Fig. 12 ).

Mature (three instar) larvae leave the fruit and form their puparia in wet soil. There is only one generation a year; puparia are formed in middle–late May and overwinter at this stage.

DESCRIPTION OF IMMATURE STAGES. Third instar larva. Body length 4.7 mm, maximal width 1.2 mm.Body shape cylindrical, tapering anteriorly. Creamy white, integument regularly covered with transparent spinules ( Fig. 11 ). Creeping welts are not developed. Anterior spiracles bicornuate, each cornu with 7–8 papillae ( Fig. 9 ). Cephalopharyngeal skeleton strongly sclerotized and massive ( Fig. 8 ). Mandibles large without accessory dents. Hypopharynx short. Pharyngeal sclerite with dorsal cornu longer than the ventral. Dorsal cornu with narrow thin long window. Ventral cornu with large open window.

Terminal segment of the body with two short respiratory tubes. Spiracular plates flat without developed spines, each with three identical radial spiracular openings ( Fig. 10 ). Terminal segment with 5 pairs of tubercles. Perianal pad transverse, anus is situated in a longitudinal cleft.

Puparium. Body length 4.0 mm, maximal width 1.1 mm. Body shape cylindrical, tapering and bilobed anteriorly ( Fig. 16 ). Brown, integument regularly covered with dark spinules. Creeping welts are not developed. Anterior spiracles bicornuate, each cornu with 7–8 papillae. Cephalopharyngeal skeleton as in third instar larva ( Fig.8 ). Terminal segment of the body ( Figs 13–15 ) with two short respiratory tubes. Spiracular plates flat without developed spines, each with three radial spiracular openings ( Fig. 10 ). Terminal segment with 5 pairs tubercles 4 of them (dorsal, lateral, subventral, subanal) are large and fleshy, ventral tubercles are small ( Figs 13–15 ). Perianal pad brown, transverse, anus is situated in a longitudinal cleft ( Figs 15, 16 ).

Figures

Figs 1–3. Acerocnema breviseta (Zetterstedt), adults: 1 — male (collection specimen), lateral view; 2 — male on a stem of Corydalis solida; 3 — female in grass near Corydalis solida. Рис. 1–3. Acerocnema breviseta (Zetterstedt), имаго: 1 — самец (коллекционный ЭкЗемплЯр), сбоку; 2 — самец на стебле Corydalis solida; 3 — самка на траве около Corydalis solida.

Figs 4–7. Corydalis solida (L.) Clairv.: 4 — general view; 5 — inflorescence with flowers; 6 — same, with fruits; 7 — fruits (on the left, an open fruit with seeds). Рис. 4–7. Corydalis solida (L.) Clairv.: 4 — обЩий вид; 5 — соцветие с цветками; 6 — то Же, с плодами; 7 — плоды (слева вскрытый плод с семенами).

Figs 8–12. Acerocnema breviseta (Zetterstedt), third instar larva: 8 — cephalopharyngeal skeleton; 9 — cephalic segment, ventral view; 10 — posterior spiracles; 11 — general view, laterally; 12 — larva eating the seed of Corydalis solida. Рис. 8–12. Acerocnema breviseta (Zetterstedt), личинка 3-го воЗраста: 8 — ротоглоточный скелет; 9 — передний конец тела, сниЗу; 10 — Задние дыхальца; 11 — обЩий вид, сбоку; 12 — личинка, поедаюЩаЯ семЯ хохлатки Corydalis solida.

Figs 13–16. Acerocnema breviseta (Zetterstedt), puparium: 13 — terminal segment, lateral view; 14 — same, posterior view; 15 — same, ventral view; 16 — general view, ventrally.Abbreviations: an pl — anal plate; dor tub — dorsal tubercle; lat tub — lateral tubercle; suban tub — subanal tubercle; subv tub — subventral tubercle; ven tub — ventral tubercle. Рис. 13–16. Acerocnema breviseta (Zetterstedt), пупарий: 13 — Задний конец тела, сбоку; 14 — то Же, сЗади; 15 — то Же, сниЗу; 16 — обЩий вид, сниЗу. СокраЩениЯ: an pl — анальнаЯ пластинка; dor tub — дорсальный бугорок; lat tub — латеральный бугорок; suban tub — субанальный бугорок; subven tub — субвентральный бугорок; ven tub — вентральный бугорок.