Culicoides (Drymodesmyia) cacticola Wirth and Hubert

Phillips, Robert A., 2022, Culicoides Latreille and Leptoconops Skuse biting midges of the southwestern United States with emphasis on the Canyonlands of southeastern Utah (Diptera: Ceratopogonidae), Insecta Mundi 2022 (907), pp. 1-214 : 62-63

Culicoides (Drymodesmyia) cacticola Wirth and Hubert

( Fig. 106 , 160, 199, 258)

Culicoides (Oecacta) cacticola Wirth and Hubert, 1960: 653 (as C. cacticolus ; key; numerical characters; female; male genitalia; fig. female wing, palpus, spermathecae, male genitalia, parameres; California).

Culicoides (Drymodesmyia) cacticola: Wirth 1965: 131 (placement in subgenus Drymodesmyia ). Wirth et al. 1985: 14 (numerical characters; fig. female wing). Wirth et al. 1988: 24 (numerical characters; fig. female wing). Murphree and Mullen 1991: 319 (key; larva; numerical characters; fig. epipharynx, hypostoma, mandible). Breidenbaugh and Mullens 1999a: 855 (egg, larva, pupa; fig. egg, larval head, mouthparts, caudal segment, pupal respiratory trumpet, operculum, caudal segment, chaetotaxy). Borkent and Spinelli 2000: 30 (in Neotropical catalog).

Diagnosis. ( Tables 14, 15) Dark brown; wing pattern distinct; r 2 dark; distal pale spot in r 3 bilobed and 8-shaped; pale spots at ~0.3 on M 1 and ~0.5 on M 2; one pale spot in distal half of anal cell; tips of M 1, M 2, usually CuA 1, pale; otherwise CuA 1 and CuA 2 within dark areas; pore of sensory pit on palpal segment 3 <0.3 the diameter of segment, widening internally (as in Fig. 248 C. sitiens ); tibiae with faint subapical pale band; spermathecae unequal by ~1.2×, ~1.2× longer than wide; ventro-posterior membrane of male sternite 9 not spiculate; ventral apodeme of gonocoxite simple; aedeagus somewhat Y-shaped, constricting at base of median process, tapering to rounded ventrally bent tip ~0.17 width of arm spread, aedeagal ratio 0.46 (0.44–0.50, n = 10); parameres separate, narrowest diameter before first ~90° bend in apical half 0.0024 mm (0.0022 –0.0031, n = 10), apices simple pointed bent.

Distribution. California, Nevada (Clark County, new state record), Utah (Washington County, new state record), Arizona, Texas, Baja California Sur, Sonora ( Monarch 2021). A male was collected with UVLT on 2 April 2019 at 36.14032°N 114.72704°W and 384 m elevation in Nevada.

Larval ecology. Culicoides cacticola has been reared from rot holes in Opuntia Miller , Carnegiea gigantea ( Ryckman 1960) , and Ferocactus cylindraceus (Engelmann) Orcutt (Cactaceae) ( Breidenbaugh and Mullens 1999a). Apparently, C. cacticola uses a wide variety of cacti as larval habitats: the Utah specimens were collected from an area where only one species of cactus ( Cylindropuntia acanthocarpa [Engelmann and Bigelow] F. M. Knuth, Cactaceae ) was present.

Adult behavior. Blood-engorged females have been collected from Japanese quail ( Coturnix japonica ) and bighorn sheep ( Ovis canadensis nelsoni ) ( Mullens and Dada 1992a). Mullens and Dada (1992b) collected C. cacticola with CO 2 -baited traps and, more abundantly, at window lights.

Life cycle. Laboratory studies by Breidenbaugh and Mullens (1999a) found that wild-caught females laid an average of 103 eggs, of which 93% hatched in ~3 d at 21–25 °C. The larvae fed on the bacterial-feeding nematodes Panagrellus redivivus (Linnaeus) (Rhabditidae) and Pelodera , pupated ~19 d after hatch, and eclosed ~3 d later with a male to female ratio of 31:7.

Symbionts. Mullens et al. (1997b) experimented with the potential biocontrol parasitic nematode, Heleidomermis magnapapula in the laboratory and found it readily entered, infected, developed, and emerged from and killed C. cacticola larvae.

Atypical biology. A female collected in Riverside County, California, by Xinmi Zhang had three fully developed spermathecae instead of two with a vestigial third ( Table 12).

Remarks. The differentiation of C. cacticola and C. torridus in the Wirth and Hubert (1960) key, where the double distal pale spot in r 3 is conjoined in C. cacticola but separated in C. torridus , fails to reliably differentiate males and some females. No other characteristic was indicated to distinguish female C. cacticola from C. torridus . And though some male specimens of C. cacticola and C. torridus can be distinguished by comparing the relatively small differences of the height of the basal arch of their aedeagi and the narrowest paramere diameter before the 90° bend of the apical portion (indicated in Wirth and Hubert [1960] for C. torridus as only “relatively stout”), preliminary data from Xinmi Zhang (personal communication) show that they cannot be differentiated using either the Cytochrome c oxidase I (CO1) or 28S rDNA genes, which readily separate the other Drymodesmyia species studied. This suggests that the wing spot and genitalia distinctions are intraspecific variations and that C. torridus should be demoted to a synonym of C. cacticola .

A male identified by genitalia as intermediate between C. cacticola and C. torridus (and confirmed by CO1 and 28S rDNA genetics [Xinmi Zhang, personal communication]), collected by Xinmi Zhang with a CO 2 - baited trap on 28 June 2019 at the Boyd Deep Canyon Desert Research Center, Riverside County, California, 33.67653°N 116.36969°W at 190 m elevation, had a subapical spine on each paramere (similar to those circled in Fig. 90 C . calexicanus). Within the Drymodesmyia of North America this characteristic is described for only C. bakeri (but with 4–6 spines). However, the specimen’s distinct single distal pale spot that does not reach the wing margin in the anal cell excludes that identification.

Figures

Figures 104–109. Male genitalia of Culicoides subgenus Drymodesmyia, ventral view. 104) C. butleri (Greenlee County, AZ). 105) C. butleri (Gila County, AZ [FSCA]). 106) C. cacticola, bottom of basal arch of aedeagus delineated (San Diego County, CA [BM]). 107) C. jonesi (Greenlee County, AZ). 108) C. sitiens. 109) C. torridus, height (h) of basal arch of aedeagus indicated (San Diego County, CA [BM]).

Figures 88–93. Male genitalia of Culicoides, ventral view. 88) C. luglani, submedian processes of parameres circled. 89) C. crepuscularis, ventral apodeme of gonocoxite circled. 90) C. calexicanus, apices of parameres circled, apex of aedeagus delineated. 91) C. hawsi (paratype, Modoc County, CA [FSCA]). 92) C. palmerae, sharp lateral shoulders on median process of aedeagus indicated (A). 93) C. utahensis.