Parasaissetia nigra (Nietner, 1861)

Mrabti, Imane, Benzahea, Hayat, Grijja, Hassan, Najiba, Brhadda, Rabea, Ziri, Afechtal, Mohamed & Watson, Gillian W., 2025, First record of nigra scale, Parasaissetia nigra (Nietner, 1861) (Hemiptera: Coccidae), in Morocco, Zootaxa 5696 (4), pp. 597-600 : 597-599

Parasaissetia nigra

is highly polyphagous, feeding on host-plants in about 294 genera belonging to 100 plant families. It attacks numerous economically important crops, including avocado ( Persea americana Mill. ), citrus ( Citrus spp.) and coffee ( Coffea spp. ), as well as a wide range of ornamental plants ( García Morales et al. 2016). Females are mainly found on leaves and young shoots but can also infest fruits ( Hamon & Williams 1984). Reproduction is strictly parthenogenetic, with males considered absent ( Smith 1944), although a few historical observations reported males without subsequent taxonomic confirmation ( Green 1904; Miller 1991). The adult female does not secrete an ovisac but produces eggs over a period of about nine months, these being protected beneath her body for one to three weeks until they hatch ( Smith 1944; Gill 1988).

Between May 2024 and July 2025, extensive entomological surveys were conducted in 78 orchards across Morocco, including 37 avocado and 41 citrus plantations. These orchards were located in 11 provinces covering the northwestern, central, and Atlantic coastal regions of the country: Salé, Rabat, Kénitra, Sidi Kacem, Sidi Slimane, Larache, Chefchaouen, Azrou, Meknès, Azemmour and El Jadida.

During the surveys, an atypical soft scale insect colonizing leaves and young shoots was recorded for the first time. Adult female specimens were prepared on microscope slides following the EPPO protocol ( EPPO 2002, 2005), with minor modifications ( Mrabti et al. 2024; Ait Badou et al. 2024). Morphological identification was performed on adult females using the dichotomous keys in Ben-Dov (1978), Germain (2003), and Abdul-Rassoul & Al-Mallo (2016). The main diagnostic characters of the slide-mounted adult female are: body outline elongate oval to pyriform, slightly narrowed at anterior end; marginal setae slightly fimbriate; dorsum becoming convex and sclerotized with a pattern of polygonal reticulations at maturity; dorsal submarginal duct tubercles and pocket-like sclerotizations present; dorsal setae cylindrical, blunt and often slightly capitate; anal plates lacking subdiscal and discal setae; venter with a complete submarginal band of one type of slender tubular ducts; and legs lacking free tibio-tarsal articulations and tibio-tarsal scleroses ( Kondo & Lin 2022). The determination was subsequently confirmed by Dr Gillian W. Watson based on photomicrographs of archival slide preparations ( Natural History Museum , London, UK).

Parasaissetia nigra was recorded in three Moroccan orchards: a citrus orchard in Kénitra ( 34.295936, -6.485427) and two orchards in Salé Bouknadel, on Persea americana Mill. ( 34.143972, -6.717500) and Citrus spp. ( 34.119997, - 6.720471), respectively. Infestations were restricted to leaves and shoots, and no physiological symptoms or significant economic damage were observed ( Fig. 1 ).

These findings represent the first record of P. nigra in Morocco. Its current distribution in the country appears to be geographically limited, with relatively low population densities. Nevertheless, given the species’ broad host range and expansion potential, systematic entomological monitoring is recommended. Favorable environmental or climatic conditions could facilitate its permanent establishment and increase its long-term economic impact.

Figures

FIGURE 1. Parasaissetia nigra (Nietner) in life, illustrating morphological and color variations according to age and host plant: (A) Dorsum of second-instar nymph; (B) Dorsum of pre-reproductive adult female; (C) Dorsum of mature adult female on a citrus twig, flat to moderately convex, shiny dark brown, with slight convexities along midribs; (D) Ventral view of mature adult female on a citrus leaf, with positions of stigmatic clefts indicated by traces of white wax secreted by the spiracular discpores, and anal cleft inconspicuous; (E) Dorsal view of mature adult female on an avocado twig, pyriform, slightly narrowed anteriorly, moderately convex, purple-black; (F) Ventral view of reproductive adult female showing eggs deposited in a cavity beneath the abdomen. Photographs by I. Mrabti, H. Grijja and H. Benzahra.