Parthenolecanium corni (Bouché)

Moghaddam, Masumeh & Watson, Gillian W., 2024, The Scale Insects Of Iran (Hemiptera: Coccomorpha) Part 3 The Soft Scales (Coccidae) And Other Families, Zootaxa 5542 (1), pp. 1-202 : 72-74

Parthenolecanium corni (Bouché)

( Fig. 29 , Plate 3B , distribution map Fig. 91J )

Lecanium corni corni Bouché, 1844: 298 . Parthenolecanium corni apuliae (Nuzzaci) ; Ben-Dov 1993: 219. Parthenolecanium corni (Bouché) ; Moghaddam 2009: 9.

Field characteristics: Adult female extremely variable in shape and coloration, depending on the host-plant and age of the insect: on leaves, semitransparent yellow-green; on twigs, mottled yellow and brown. Old females heavily sclerotized, strongly convex. Young adult females before egg-laying, and second- or third-instar nymphs occurring on twigs, well camouflaged and very difficult to detect ( Gill 1988).

Microscopic diagnosis: Slide-mounted adult female body oval. Stigmatic clefts not developed. Anal cleft about 1/6 th of body length.

Dorsum. Derm membranous in young specimens, but becoming sclerotized at maturity; without clear areolations. Setae of 2 sizes: (i) large, stout, blunt and spinelike, present in a more-or-less double line medially anterior to anal plates, extending as far forward as mouthparts; and (ii) much smaller, blunt and spinelike, scattered throughout. Pores of 2 types present throughout: (i) small, circular simple pores, and (ii) bilocular microducts, each with an inner filament. Preopercular pores relatively large and circular with granular centres, present just anterior to anal plates. Duct tubercles present, large and convex, number variable, 0‒18 around submargin. Pocket-like sclerotizations present. Tubular ducts of 1 type present, with outer ductule almost as long as narrow inner ductule, which ends in a small terminal gland; scattered throughout. Anal plates together quadrate, each plate with 3 small apical setae and 1 along inner margin. Anal ring with 8 setae.

Margin. Marginal setae each bluntly spinose, present in 2 rather uneven rows; each side with 11‒20 setae between stigmatic areas. Stigmatic setae in groups of 3 in each stigmatic area on margin, median seta longest and usually slightly curved.

Venter. Derm completely membranous. Pregenital disc-pores mostly each with 10 loculi, abundant around anogenital fold, becoming progressively fewer anteriorly across preceding abdominal segments; a few also present mesad to each coxa and laterad to each metacoxa. Spiracular disc-pores each with 5 loculi, present in a narrow band between each spiracle and margin, with 1 or 2 disc-pores present more medially. Microducts abundant in a submarginal band, much fewer medially, particularly on abdomen. Tubular ducts of 3 types, all with inner ductule much narrower than outer ductule: (i) small duct with short outer ductule, very fine inner ductule and no terminal gland, present in small submarginal groups between antennal bases and on either side of anal cleft; (ii) slightly larger duct with a large terminal gland, sparsely present mediolaterally on head, thorax and abdomen; and (iii) fairly large duct with fairly wide outer ductule, moderately wide inner ductule and large terminal gland, present in broad submarginal band extending from just anterior to each antennal base to near anal cleft. Three pregenital segments each with a pair of long setae; also with 2‒5 pairs of setae between antennal bases; other setae small and sparse. Legs well developed, each with separate tibia and tarsus but no articulatory sclerosis; claw long and narrow, with a minute denticle; claw digitules dissimilar, with 1 broader than other; tarsal digitules both fine and about as long as claw digitules. Antennae each with 7 segments.

Distribution: Parthenolecanium corni is a cosmopolitan species ( García Morales et al. 2016); in Iran, it is found in Azarbaijan -e Sharghi, Gilan and Tehran provinces ( Moghaddam 2013).

Host-plants: The species is highly polyphagous, feeding on hosts belonging to over 50 plant families. In Iran, it has been recorded on Crataegus azarolus ( Rosaceae ), Fraxinus excelsior ( Oleaceae ) and Solanum tuberosum ( Solanaceae ) ( Moghaddam 2013).

Economic importance: Not of any economic importance in Iran.

Natural enemies: In Iran, the following parasitoid wasps ( Hymenoptera ) attack P. corni : Encyrtus infidus (Rossi) , Metaphycus near eruptor (Howard), M. parthenolecanii Japoshvili , M. stanleyi Compere and Microterys sylvius (Dalman) ( Encyrtidae ); and Pachyneuron muscarum (L.) ( Pteromalidae ) ( Jalilvand et al. 2013; Japoshvili et al. 2015). The predator Oenopia conglobata (L.) ( Coleoptera : Coccinellidae ) has been recorded attacking the scale in Iran ( Jalilvand et al. 2013).

Figures

PLATE 3. Coccidae continued: A, Palaeolecanium bituberculatum (Signoret); B, Parthenolecanium corni (Bouché); C, Rhizopulvinaria artemisiae (Signoret); D, Rhizopulvinaria turkestanica (Archangelskaya); E-1 and E-2, Saissetia miranda (Cockerell & Parrott); F, Sphaerolecanium prunastri (Boyer de Fonscolombe); G, Stotzia ephedrae (Newstead).

FIGURE 29. Adult female of Parthenolecanium corni (Bouché), reproduced from Gill (1988) page 66, fig. 22, with permission from the author and California Department of Food & Agriculture, Sacramento, California, USA.

FIGURE 91. Distribution maps of scale insect species in Iran covered in this work. A, Kermes quercus (Linnaeus); B, Kermes spatulatus Balachowsky; C, Neoacanthococcus pamiricus (Bazarov); D, Neoacanthococcus tamaricicola Borchsenius; E, Nidularia balachowskii Bodenheimer; F, Orthezia urticae (Linnaeus); G, Ortheziola marottai Kaydan & Szita; H, Palaeolecanium bituberculatum (Signoret); I, Palmaspis phoenicis (Ramachandra Rao); J, Parthenolecanium corni (Bouché); K, Parthenolecanium persicae (Fabricius); L, Phoenicococcus marlatti Cockerell.