Valid Names Results

Stictococcus vayssierei Richard, 1971 (Stictococcidae: Stictococcus)

Nomenclatural History

• Stictococcus vayssierei Richard 1971: 592. Type data: CAMEROON: Yaoundé, on Manihot esculenta, 13/12/1969. Holotype, first instar, Type depository: Paris: Museum National d'Histoire naturelle, France; accepted valid name Notes: 1 adult male allotype, 10 paratypes (first instars and females) in MNHM. Illustr.
• Stictococcus vayssieri Richard, 1971; Vea & Grimaldi 2015: 64. misspelling of species epithet
• Parastictococcus vayssierei Hodgson 2020: 115. lapsus calami
• Stictococcus vayssieri Richard, 1971; Vayssières, et al. 2021: 8. misspelling of species epithet

Common Names

• cassava brown root scale TchuanHuLe2000
• cassava root scale AmbeNtAw1999
• escama Africana de la raíz Watson2022a

Ecological Associates

Hosts:

Families: 14 | Genera: 17

Associates:

Families: 1 | Genera: 2

Geographic Distribution

Keys

• Hodgso2020: pp.114-115 ( Adult (M) ) [Stictococcidae]
• WilliaMaMi2010: pp.11 ( Adult (F) ) [Key to adult females of Stictococcus species (except S. tuberculatus)]
• Richar1976: pp.668 ( Adult (F) ) [Key to species of Stictococcus]

Remarks

• Systematics: Stictococcus vayssierei is close to S. sjostedti, but can be differentiated by the bidentate marginal processes less broad, thicker marginal spines; spines of dorsal integument differently formed; many glands in the pleural zone; a spine bifid in segments 3 and 4 of the antenna and on the dorsal face of the tibia; the tarsus longer than the tibia; digitules of the less thick tarsus (Richard, 1971).
  The ventral marginal setae of this species are bullet-shaped as in S. formicarius but the latter species possesses flower-shaped dorsal setae and these are absent from S. vayssierei. Furthermore, the dorsal depressions are very shallow and sometimes difficult to locate in S. vayssierei, whereas in all other species the dorsal depressions are much more conspicuous. (Williams, et al., 2010)
• Structure: Males of Stictococcus vayssierei are apterous and difficult to see with the naked eye (Ambe et al., 1999). However, Hodgson (2020) considered that as the mesothorax is normally developed (i.e., heavily sclerotised and apparently similar in structure to that of alate species), that the specimen may have been damaged and that this species was alate. On the other hand, because S.. vayssierei feeds on the roots of its host plants, the possession of wings might be a disadvantage Live adult females are usually brown except black in older adults. Individuals all sessile. Sclerotization of anal ring and median line well marked. Waxy secretion present on both margin and on dorsum and appearing as whitish dots. Slide-mounted adult females: The main differences between the adult and the other developmental stages were the presence of four opercula surrounding the anal orifice, the number of long setae on the posterior and the anterior opercula, and the appearance of the genital cleft. Live second instar nymphs are usually purple-red (94%), but occasionally yellow (6%). Individuals change feeding site after moulting. Sclerotization of anal ring and the median line marked. When present, whitish waxy secretion concentrated near the margin and in contact with the substrate. Slide mounted second instar: The main difference between the second instar and the first and third instars is the number of long setae on the anterior and posterior opercula surrounding the anal orifice. Live first instar nymphs are usually purple-red, but occasionally yellow. Very mobile individuals. Sclerotization of the anal ring and the median line weakly developed. Slide mounted first instar: The main difference between the first and the other two instars is the presence of a row of setae in the internal surface of anterior operculum and the absence of setae on the posterior operculum
• Biology: Females are viviparous (Ambe et al., 1999). Ants, specifically Anoplolepis tenella Santschi, are the principal agents for the dispersal of S. vayssierei in southern Cameroon. (Dejean & Matile-Ferrero, 1996) Fotso, et al., 2015, demonstrated that S. vayssierei can move for short distances to find a host plant, but it relies on A. tenella workers for active transport and dispersal over longer distance as likely occurs in the field during the colonization of new plantedcassava fields. Experimental reduction of ant density resulted in consequent and significant reduction of the scale infestation and a 16% yield increase in cassava, (Doumtsop, et al., 2019)
• Economic Importance: Ngeve (2003) indicated that pest frequency was only 12.5% in 1990, but increased to 87.5% by 1994. Attacks were more severe when cassava was planted on the flat rather than on ridges, and more severe when intercropped with other plants such as maize and groundnuts than when planted alone. Incidence and density were significantly higher on cassava compared to aroids. However, aroids were more infested than cassava in the savannah area while the opposite was observed in the forest area. (Doumtsop, et al., 2019)
• General Remarks: Best description and illustration by Richard (1971). Detailed descriptions and illustrations of the 3 developmental stages in Tindo, et al. (2006).

Illustrations

Citations