Description of Plum Scale Immatures Stages ( Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccidae)

: Species identification of scale insects is usually made during the adult female period. However, early nymphal stages are targeted in the control of these pests. Plum Lecanium , Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccidae) is an economically important pest of stone fruits, almonds, and ornamental Prunus species in Turkey as well as worldwide. The first–instar, second–instar male and female, and third–instar female of plum scale are redescribed and illustrated. We present diameters, position, distribution, and number of pors (simple, bilocular, trilocular pores, micro–ducts, tubular ducts, spiracular disc–pores), and marginal setae in all immature stages of Plum Lecanium that have not been given descriptions from different authors previously. We recorded the presence of heavy rimmed pores in second–instar males and females. An identification key is provided for


Introduction
Sphaerolecanium Sulc (Hemiptera: Coccidae) is a monotypic genus (Hodgson, 1994) and S. prunastri (Boyer De Fonscolombe) is well known as globose scale, hemispherical plum scale, or plum lecanium that is an economically significant stone fruit pest as well as a pest on ornamental Prunus spp.
Yuzuncu Yil University Journal of Agricultural Sciences Volume 31, Issue 4, 31.12.2021 (Rosaceae) worldwide. Although it is most widespread in Palearctic (Kozár, 1998;Kaydan et al., 2013), it has also been recorded in Nearctic Region (Pfeifer, 1997;Garcia et al., 2021). Besides Prunus species, it is recorded on Amygdalus spp., Malus silvestris, Cydonia spp., Pyrus spp. (Rosaceae) and Vitis spp. (Vitaceae) (Kosztarab and Kozár, 1988). It is a severe pest on Japanese plum, stone fruits, especially cherry, cheery plum and almond, peach, in Armenia, Greece, Turkey and more common on ornamental plum than fruit plum in the USA (Kosztarab, 1959;Babayan, 1986;Kosztarab and Kozár, 1988;Ülgentürk et al., 2001). Sphaerolecanium prunastri has an economic impact on plum production, peach and apricot industries and ornamental plants in Turkey (Bodenheimer, 1958;Ülgentürk and Toros, 1999;Ülgentürk et al., 2004;Anonymous, 2008;Özgen and Bolu, 2009;Akşit and Apak, 2013;Çiftçi and Bolu, 2021). It has one generation in a year and overwinters in the second nymph stage on stone fruit trees in Turkey (Anonymous, 2008;Akşit and Apak, 2013). Sphaerolecanium prunastri is sap-feeding on twigs and branches of their host (Kozar, 1989). Besides the direct effects of feeding by this soft scale the production of honeydew covers the plant surface, which in turn produces sooty mold, reducing photosynthesis which has a negative impact on fruit quality and quantity. The honeydew also might cover the plum fruits, giving especially early plums a dirty look (local varieties Havran and Can plum), complicate of harvest, and reducing their market value (Anonymous, 2008). Producers notice Plum Lecanium infestations usually not before a large amount of honeydew has already been produced. At this stage sclerotization of the female has already begun, and all tree branches are covered in honeydew, rendering all intervention useless at this point. Early plum varieties run a high risk of containing pesticide residue, an intervention with pesticides is therefore not appropriate. Sphaerolecanium prunastri has many natural enemies, but they are not frequently enough to control the population of plum lecanium (Ülgentürk et al., 2004;Özgen and Bolu, 2009).
Also, Didesmococcus unifasciatus (Archangelskaya) and Rhodococcus turanicus (Archangelskaya) (Hemipteran: Coccidae), which are very similar appearances after maturity of a female with plum lecanium, was recorded pests on Prunus persica in Hakkari province, Eastern Anatolia (Kaydan and Kozár, 2010). After that Didesmococcus unifasciatus is recorded as an almond and peach pest in Diyarbakır provinces (Bolu, 2012;Çiftçi and Bolu, 2021). For this reason, these three species, which are pests of stone fruit trees in Eastern and Southeastern Anatolia, can be confused with each other.
The study of immature stages of the Coccidae is in its infancy. Most of the research has been conducted on first-instar nymphs, with little attention being paid to other immature stages (Williams and Hodges, 1997). Although the adult female of S.prunastri was described by Boyer de Fonscombe in 1834, and subsequently redescribed by Borchsenius (1957), Kosztarab and Kozár (1988), Hodgson (1994), and male by Giliomee (1967), immature stages of S. prunastri were described very briefly and limited illustrations made by Silvestri (1919), Borchsenius (1957), Rehacek, (1960. After that, Ben-Dov (1968) described the first and second instars and described and illustrated third-instar female first time.
The aim of the study is to redescribe and illustrate first, second (male and female), and third instar female and offer an identification key for all instars of S. prunastri and help to distinguish similar species and timing of control strategies for this pest.

Material and Method
The scale crawlers emerge from the eggs between May-July and then settle on twigs where they take feeding positions and overwinter as second-instar stage and, depending on climatic conditions, in Ankara. Branches infected by immature stages of plum lecanium were collected every week between the months, March and November Ankara Parks and some distinct, in 2014 and examined under a stereomicroscope. Nymphs were put into 70% alcohol and stored in Coccidiology Laboratory at Ankara University, Plant Protection Department. At the same time, some infested branches were kept in the climatic room to obtain more specimens in case of some problem in progress. For a slide-mounting the method of Kosztarab and Kozár (1988).
First-instar nymph (n=10) (Figure 1 Dorsum; derm membranous. Simple pores with the granulate surface, each 2 µm wide in submarginal and submedial longitudinal lines, extending from head apex to anal lobe, with about 10 pores in each line. Bilocular pores each 2 µm wide, about 9-11, in a longitudinal line between lines of simple pores. Anal plates reticulated; each sub-triangular; 25-40 µm long, 20-30 µm wide; each plate with 1 apical setae, 300 µm long, plus 2 sub-apical setae, each 15-18 µm long and one inner setae. Ano-genital fold with 1 pair of anterior margin and lateral margin setae, each 5-18 µm long. Anal ring with pores and 6 setae, each setae 25-34 µm long. Dorsal setae present three on the thorax, each 4-5 µm long. A pair of trilocular pores, each 3 μm wide, placed anterior to each basal antennal segment, near body margin in specimens from plum threes but absent in the specimens from cherry threes. Margin. Marginal setae long (10-13 µm), 1 µm wide, blunted on the apex, distributed in a single line along body margin as follows: 12 between anterior stigmatic setae; 2 between each stigmatic area; 8 between posterior stigmatic area and anal cleft. Stigmatic clefts narrow; spiracle setae are obviously shorter than margin setae, each stigmatic area with 3 spiracle setae, medial one slightly bigger (7-12 µm long) and 2 µm wide, rounded, lateral ones 5-8 µm long well differentiated in shape from marginal setae. The basal socket of medial spiracle setae 4-5 µm and socket of lateral ones 3-5 µm. Eyes 10 μm wide close to body margin.
Comments: Borchsenius (1957) offered descriptions of adult females and the first-stage of S. prunastri (Table 1). In the first instar, he described major characteristics such as spiracle setae, medial one 7-8 μm, and others 5-6 μm long. Each stigma with 3 quinquelocular spiracular disc-pores band broadening near margine. Ben-Dov (1968) provides more detail about the number of marginal setae in the first instar (Table 1). S. prunastri collected from Ankara in the first instar is similar to Ben-Dov's description regarding the number and distribution of spiracular disc-pores and stigmatic setae, from our description differs in the number of marginal setae between anterior stigmatic areas; in having microtubular ducts, rows of simple and bilocular pores and one pair of trilocular pores on dorsum. In addition, presence of stigma disc-pores with 3 to 7 loculi. In the works of both previous authors, no descriptions of dorsally simple, bilocular, and trilocular pores are found. General appearance. Body elongated oval; Mounted material. Body elongated oval; 910-1175 µm long, 540-675 µm wide. Dorsum. Derm membranous. Preopercular pores are absent. Simple pores with the granulate surface, each 1-2 µm in diameter, throughout in a few numbers scattered. Bilocular pores each 2 µm in diameter, scattered. Tubular ducts of two sizes: (i) larger ducts each with a very long outer ductule 13-15 µm long, a shorter inner ductule about 8-15 µm long, cup-shaped invagination, 3-5 µm wide; and a terminal gland end, 2-4 µm wide: present in submarginal band one duct wide, with one row 32-39; and radial posterior in the middle of the abdomen on each side 6-11; and (ii) smaller, stouter ducts, each with outer ductule 5-8 µm long, inner ductule, 5-13 µm long, cup-shaped invagination, 4-5 µm wide; and with a terminal gland end, 3-4 µm wide: present in submarginal lines of the tubular duct on the abdomen as well in posterior radial line, between larger ducts. Anal plates each sub-triangular; 25-45 µm long, 63-73 µm wide; each plate with 4 apical setae, middle one 18-23 µm long, lateral ones 13-19 µm. Ano-genital fold with 2 pair of anterior margin setae 15-18 µm long and lateral pair 7-10 µm long, some specimens have two setae on lateral margin. Anal ring with pores and 6 setae, each setae 60-80 µm long.
Margin. Marginal setae long and thin, on the top slightly curved with round apex, they are not arranged along marginal fringe in the same line, with a big variation in length, each 15-27 µm long and 3 µm wide, distributed along body margin as follows: 12 between anterior stigmatic setae; 2 between each stigmatic area; 10-12 between posterior stigmatic area and anal cleft. Stigmatic clefts slightly shallow; each stigmatic area with 3 spiracle setae, all subequal in shape rounded apex, medial one 7-8 µm long and lateral ones 8-9 µm long, well differentiated in shape from and shorter than marginal setae, Eyes visible on mounted specimens 10-15 µm wide.
Ventral setae hairlike: 2 pair inter-antennal setae, long pair 38-55 µm long and short pair 5-13 µm long. One pair of setae anterior to basal antennae segment 12-18 µm long. Setae, 8-15 µm long, in a submarginal band extending from head to anal lobe; 7 setae 5-13 µm long in a second row extending from posterior stigmatic furrow and innermost line from posterior spiracle to anal lobe, 4-5 setae in third submarginal lines, 3-4 µm long. One seta, 3-5 µm long, medial to each coxa. Three pairs of pregenital setae, each 40-50 μm long. Comments: Ben-Dov (1968) described the second-instar male and female instar of S. prunastri as similar in number and position of marginal setae (without giving their number and shapes), but his description of males differs from the females as the males have tubular ducts (Table 1). For S. prunastri second-instar male, we present in this work two types of tubular ducts and indicate their position, simple pores, bilocular pores on dorsum, and presence of heavy rimmed pores on ventrum. These characteristics could help to distinguish the second stages male of Plum Lecanium from other second-instar males of coccids. Miller & Williams (1990) have described a test for S. prunastri that sutures reduced posterolateral and posterior transverse sutures fused to form a single transverse posterior suture. Submarginal lines of the tubular duct on the abdomen as well as radial posterior line, between larger ducts in our description, explain this posterior suture in the test.
Margin. Marginal setae two types, slightly curved, some straight with rounded apex, some with spine-like apex, each 18-23 µm long and 2-3 µm wide, they are not arranged along the marginal fringe in a line: 12 between anterior stigmatic setae; 2 between each stigmatic area; 9-13 between posterior stigmatic area and anal cleft. Stigmatic clefts absent; each stigmatic area with 3 spiracle setae, well different in shape than marginal setae, all with rounded apex, shorter than marginal setae, medial spiracle setae 8-12 long with a basal socket 5 μm wide, lateral spiracle setae 7-9 µm and basal socket 4 µm wide, in most cases the medial setae is slightly longer than the lateral setae. Eyes on the mounted material on some specimens 8-13 μm wide, located on the inner part of the head, on most specimens they cannot be seen.
Comment: In this paper, on the dorsum of second-instar female of S. prunastri, many characteristics such as simple, bilocular, heavy rimmed pores were described, and their dimensions were given. We have determined large numbers of heavy rimmed pores on the dorsum and ventrum of the second instar female. These pores are present only ventrally in the second instar of males. Ben-Dov (1968) described only the number of marginal setae and spiracular disc-pores in second-instar females (Table 1). In his description was not mentioned the presence of dark-rimmed pore on ventrum and dorsum of second instar of female. Small differences between the numbers of these spiracular disc-pores can be explained by geographical occurrence and differences in host plants. General appearance. Body round; color dark gray similar to branches. Mounted material. Body round; 1350-1875 µm long, 1000-1475 µm wide. Dorsum. Derm membranous. Preopercular pores were absent. Simple pores with a granulate surface, each 2 µm wide, spread around the whole body to a greater extent than in second-instar nymph. Bilocular pores each 2 µm wide, spread around all body surfaces. Heavy rimmed pores 3 µm wide, abundant and more numerous than in second-stage females and scattered all over the dorsum. Anal plates sub-triangular, 65-143 µm long, 65-138 µm wide; each plate with apical setae, the middle one 38-45 µm long, laterals 20-50 μm long, and 1 inner setae. Ano-genital fold with 3 pair of setae on anterior margin, longer pairs 33-53 µm long, shorter pairs 20-35 µm long, 1 small seta on lateral margin 5-15 µm long. Anal ring with pores and 6 setae, each 105-150 µm long.
Margin. Marginal setae slightly curved with round apex, arranged along the marginal fringe, not in a clear line, each 28-30 µm long and 3 µm wide, distributed as follows: 12-14 between anterior stigmatic setae; 5-6 between each stigmatic area; 19-26 between posterior stigmatic area and anal cleft. Stigmatic clefts absent, each stigmatic area with 3 spiracle setae, different in shape and shorter than marginal setae, medial spiracle setae longer than the lateral ones, rounded on the apex, medial spiracle setae 17-20 µm long with basal socket 5 μm wide, lateral spiracle setae 15-18 µm long and basal socket 5-6 µm wide. Eyes on the mounted material cannot be seen.
Ventral setae hairlike: three pairs of inter-antennal setae, innermost long pair 50-73 µm long, middle one 8-13 µm and short pair 4-5 µm long. Seta, 8-20 µm long, in a submarginal band extending from head apex to anal lobe and second submarginal line 5-9 μm from anterior spiracle area to anal lobe; third submarginal line with 5-8 µm long innermost line on the abdomen posterior from metacoxa to anal plate. Two or three setae, medial to each coxa 3-8 µm long. One pair of pregenital setae, each 85-103 μm long, as well as one more pair setae on the next two abdominal segments above were found. Microducts each 3 µm wide, in a single submarginal band from head apex to anal lobe, on the head 4 of them around antennae scapulae. A pair of setae anterior to basal antenna segmsegments23 µm long. Heavy rimmed pores are more abundant, scattered all over the body on the venter, 3 µm long. They are more abundant than in second-instar nymph.
Comment: S. prunastri third-instar female was described for the first time by Ben-Dov (1968). At the body margin, he described some marginal setae, with the same number anteriorly between the eyespots, on each side between eyespots and anterior stigmatic area and between stigmatic areas laterally, as for second-instar and third-instar female, but for third-instar female, number on each side of the abdomen increases 15-18, spiracular disc-pores 15-28 in number, on ventrum submarginally, heavy rimmed pores distributed 3-4 pore wide from each other (Table 1). This paper describes thirdinstar female of S. prunastri collected in Ankara and shows some differences from Ben-Dov's (1968) descriptions. Spiracular disc-pores have 3, 4, 6, 7 loculi, each stigmatic area anterior with a 10-12 quinquelocular spiracular disc-pores band, each stigma area posterior with a 12-16 spiracular disc-pores band broadening near the margin. Heavy rimmed pores are more abundant, scattered all over the body on venter and dorsum of a specimen from Ankara, with ventral microduct in single submarginal and without ventral submarginal band extending around the body as described by Ben-Dov (1968).    Borchsenius, 1957, B: Ben-Dov, 1968 and C: Durovic &Ülgentürk