Pulvinaria indica Avasthi & Shafee, 1985

Joshi, Sunil, Ramya, R. S., Navik, Omprakash, Pawar, S. A., Hole, U. B. & Tambe, A. B., 2019, Redescription of Pulvinaria indica Avasthi & Shafee, 1985 (Hemiptera: Coccomorpha: Coccidae) with new host and distribution records, Zootaxa 4545 (1), pp. 133-138 : 134-136

Pulvinaria indica Avasthi & Shafee, 1985

Pulvinaria indica Avasthi & Shafee, 1985: 1290 . Type data: INDIA: Andhra Pradesh, Visakhapatnam, Simhachalam, on Duranta repens . Holotype, female, Type depository: Department of Zoology , Aligarh Muslim University, Aligarh, India.

Material examined: INDIA: Maharashtra, Rahuri, Gotumbe Akhada (19.3927° N, 74.6488° E) on Capsicum annuum L. ( Solanaceae ), 17.XI.2017, Ramya, R.S. and Omprakash Navik coll.

Appearance in life ( Fig. 1 ): Colonies were found on roots ( Fig. 1A ) and aerial parts just above ground. Female oblong ovate, flat initially, but with age becoming moderately convex in median portion ( Fig. 1B ). Nymphs reddish brown initially but as they grow, becoming yellowish brown with dark brown speckles in submarginal area that merge to form bars on submargin of abdomen. Anal plates moderately dark, surrounded by paler area. Each stigmatic area marked with a dark bar; three similar bars present on head. Mid-dorsal area with two broad dark bars arising from area anterior to anal plates and extending to anterior margin of head ( Fig. 1D ). A female about to start oviposition turns darker brown; the posterior abdominal area turns whitish and a cottony ovisac begins to be secreted from venter of abdomen. Ovisac as wide as body and up to five times as long, sometimes curved, with three main longitudinal furrows forming four longitudinal ridges ( Fig. 1C ). Eggs shiny, ochre-coloured. After oviposition, female becomes shrunken and darker. Avasthi & Shafee (1985) did not mention which parts of the host D. repens (on which the species was first collected and described by them) were infested; they also did not mention any association with attendant ants. Ants were not found associated with the scales in the recent collection.

Description of slide-mounted adult female ( Fig. 2 ). Body shape and size: Broadly oval, in many cases almost circular ( Fig. 2A ), 2.00‒ 3.01 mm long, 2.00‒ 2.42 mm wide, length 1.00‒1.24 times width. Anal cleft 0.38‒0.44 mm long, 0.15‒0.18 times as long as body length.

Margin: Spiracular clefts not differentiated, lacking sclerotisation. Spiracular setae usually numbering 3 at the end of each spiracular furrow (except in two specimens with 4 setae and one specimen with 5); anterior spiracular furrow ending with all 3 setae of similar length (each 27‒45 µm) ( Fig. 2C ). Posterior spiracular furrows each ending with lateral setae each 29‒47 µm long, straight or gently curved with base slightly swollen, bluntly pointed, apex sometimes bifurcate or trifurcate ( Fig. 2E ); median seta 62‒75 µm long (1.59‒2.10 times as long as lateral setae), curved, with apex bluntly pointed ( Fig. 2C ). Marginal setae ( Fig. 2B ) each 21‒33 µm long, slender, straight or curved, with apex usually bifid or fimbriate; distributed as follows: 40‒58 between anterior spiracular furrows, 12‒18 between anterior and posterior spiracular furrows on each side, and 32‒42 between each posterior spiracular furrow and anal cleft.

Dorsum: Derm in mature females with well-marked dermal areolations on marginal areas and faint areolations on medial areas ( Fig. 2F ). Dorsal setae ( Fig. 2G ) scattered, sparsely distributed, each 8‒12 µm long, thick and spinose. Submarginal tubercles absent. Discoidal pores not detected. Tubular ducts and filamentous pores absent. Anal plates ( Fig. 2H 1 ) each triangular, 123‒163 µm long, 71‒93 µm wide; anterolateral margin 11‒12 µm long, posterolateral margin 11‒12 µm long. Each plate with 3 apical setae (occasionally 4) each 17‒23 µm long, and 3 subapical setae each 37‒43 µm long ( Fig. 2H2 ). Fringe setae numbering 2 pairs, each 53‒65 µm long ( Fig. 2H2 ). Anal ring 61‒70 µm long, 21‒25 µm wide, bearing 8 setae, 152‒183 µm long; translucent pores in anal ring forming 2 rows, each pore oval, 2‒3 µm in maximum dimension ( Fig. 2I ).

Venter: Submarginal setae ( Fig. 2J ) each 5‒8 µm long, slender, straight or slightly curved, tapering, distributed as follows: 11‒14 between anterior spiracular furrows, each side with 4‒9 between anterior and posterior spiracular furrows, and 13‒16 between posterior spiracular furrow and anal cleft. Ventral setae ( Fig. 2K ) similar to submarginal setae, each 8‒14 µm long. Interantennal setae numbering 3 pairs, one pair short and two long; shorter setae each 23‒25 µm long, longer setae each 92‒153 µm long. Prevulvar setae numbering 3 pairs, each seta 92‒125 µm long. Antennae ( Fig. 2L ) well developed, 8 segmented, each 313‒402 µm long.

Lengths of antennal segments in µm: segment I, 38‒51; II, 42‒72; III, 62‒81; IV, 41‒53; V, 41‒44; VI, 24‒32; VII, 22‒24 and VIII, 42‒44. Number of hair-like setae on antennal segments: I, 2 or 3; II, 3; III, 2; IV, 1; V, 3; VI, 0 or 1; VII, 1 or 2; VIII, 4 or 5; numbers of fleshy setae: VI, 1; VII, 1; VIII, 5 or 6. Clypeolabral shield 1 12‒123 µm long, 137‒142 µm wide. Labium 63‒82 µm long, 112‒142 µm wide, with 3 pairs of setae each measuring 0.02‒0.03 µm long. Legs ( Fig. 2M ) well developed, each with tibiotarsal sclerotization and free articulation; claw without denticle; tarsal digitules slender, knobbed; claw digitules broad, equal, expanded at apex. Legs well developed. Lengths of prothoracic leg: coxa 152‒173 µm, trochanter+femur 233‒263 µm, tibia 162‒165 µm, tarsi 93‒96 µm, claw 28‒35 µm, tarsal digitule 65‒68 µm, claw digitule 41‒44 µm; mesothoracic leg: coxa 133‒163 µm, trochanter+femur 224‒232 µm, tibia 164‒168 µm, tarsi 101‒123 µm, claw 24‒52 µm, tarsal digitule 54‒63 µm, claw digitule 39‒44 µm; metathoracic leg: coxa 125‒129 µm, trochanter femur 203‒251 µm, tibia 132‒174 µm, tarsi 82‒92 µm, claw 22‒43 µm, tarsal digitule 61‒64 µm, claw digitule 39‒44 µm. Anterior spiracles ( Fig. 2N ) each 75‒84 µm long, 44‒63 µm wide across atrium. Posterior spiracles similar to anterior ones, each 79‒88 µm long, 42‒63 µm wide across atrium. Spiracular pores ( Fig. 2O ) usually quinquelocular, occasionally with 4 loculi, each 3‒4 µm in diameter, numbering 45‒52 in each anterior spiracular pore band, and 48‒52 in each posterior spiracular pore band. Spiracles each not surrounded by a sclerotic plate. Multilocular pores ( Fig. 2P ) each 8‒13 µm in diameter, with 7 loculi, central loculus with a slit, present around anal area, in transverse bands across abdomen as far forward as segment IV and with 2‒5 laterad to each hind coxa. Tubular ducts of four types present: first type ( Fig. 2Q ) with slender, short inner filament, numerous in submarginal areas of metathorax and abdominal segments, a few scattered in submarginal areas from posterior spiracle to prothorax, duct 12‒23 µm long, 1‒1.5 µm wide, inner filament 1‒4 µm long; second type ( Fig. 2R ) with inner filament a little longer and with a flowery apex, duct 12‒22 µm long and 2‒4 µm wide, inner filament slender, 11‒14 µm long, distributed in posterior part of abdomen in submarginal band; third type ( Fig. 2S ) with duct 9‒21 µm duct long and 2‒4 µm wide, inner filament very long (19‒28 µm) with flowery apex, present on inner margin of submarginal band of tubular ducts; and fourth type ( Fig. 2T ) with duct 12‒22 µm long and 2‒4 µm wide, inner filament 2‒4 µm long broad with a flowery apex, present on median part of abdominal and thoracic segments, mostly arranged in transverse rows. Microducts not detected.

Morphological variations. Several morphological variations were found within the specimens observed in the present study and between the original description and the specimens examined. With reference to the illustration made by Avasthi & Shafee (1985) and the material studied, the stigmatic spines appear to be the most variable character. The original description mentioned that the anterior clefts always have the median spine as long as the lateral spines and the posterior clefts always have the median spine more than twice as long as the lateral spines; but in the present collection there were some specimens with the anterior cleft having a long median spine and the posterior cleft having equivalent spines (four out of 15 specimens). There are usually three spines in each stigmatic cleft, but two specimens had four spines, and one had five spines of similar lengths. Also, in some specimens the stigmatic spines had bifurcate tips (10 setae were found bifurcated to various degrees). The original description also records the presence of only one type of ventral tubular duct in the cephalic, thoracic and abdominal regions; however, we observed four types of tubular duct at different locations (defined in the description above and indicated in Fig. 2 ). Similarly, the original description claims the absence of clear areas on the derm; however, the most mature females examined showed the presence of well-marked dermal areolations on the marginal areas and faint areolations on the median areas. In addition, of the 15 specimens examined, two had four apical setae on each anal plate instead of the three normal for this species.

Biology. Some colonies of P. indica were found feeding on the roots. Leaves of the plant with dense colonies had turned yellowish and some of the infested branches were completely dried out, damage caused by continuous sap extraction by the scales. The life cycle of P. indica in the field is unknown, however when reared in the laboratory on summer squash ( Cucurbita pepo L.), the scale completed its life cycle (from egg to ovipositing female) in 28‒36 days at 26‒28˚C and 51‒55% RH.

Management options. Discussion with the farmer at the collection site revealed that this pest outbreak was being experienced for the first time, however some plants infestated by P. indica had been observed in preceding years also. As chilli is regularly grown in this village, as an intercrop with lucerne (which is used as green fodder), no chemical pesticides were used to manage the pest.

Although a parasitoid, Coccophagus nigricorpus Shafee ( Hymenoptera : Aphelinidae ), is known to attack P. indica in India ( Avasthi & Shafee, 1985), we did not recover any parasitoids or predators from the colonies collected from the field. However, the scale could be easily multiplied on summer squash, Cucurbita pepo , in the laboratory. The scale insects thus produced were exposed to adults of Scymnus coccivora Ayyar and Cryptolaemus montrouzieri Mulsant ( Coleoptera : Coccinellidae ) and both these predators readily accepted P. indica as their prey.

Subterranean sucking pests are generally known to have their dispersal assisted by attendant ants, but surprisingly no ants were found to be associated with P. indica during our surveys. This provides a situation ideal for coccinellid predators to work effectively; however, their actual response in the field would need to be studied before they could be recommended as biological control agents.

Figures

FIGURE 1. Life stages of Pulvinaria indica Avasthi & Shafee. A. Colony on the roots of chilli Capsicum annuum L.; B. Colony of nymphs and adult females raised on Cucurbita pepo L. in the laboratory; C. Colony of ovipositing females showing straight and curved ovisacs; D. Close-up view of ovipositing females, showing colouration and body markings.

FIGURE 2. Taxonomic illustration of an adult female of Pulvinaria indica Avasthi & Shafee. A. Body derm; B. Marginal setae; C. Anterior spiracular setae; D. Posterior spiracular setae; E. Bifurcate and trifurcate spiracular setae; F. Dermal areolations; G. Dorsal setae; H1. Dorsal view of anal plate; H2. Ventral view of anal plate; I. Anal ring; J. Submarginal setae; K. Ventral setae; L. Antenna; M. Tarsus and claw; N. Spiracle; O. Spiracular pores; P. Multilocular pores; Ventral tubular ducts: Q. Type I; R. Type II; S. Type III; T. Type IV.