|Crop Knowledge Master|
Parasaissetia nigra (Nietner)
Ronald F. L. Mau, Extension Entomologist
Jayma L. Martin Kessing, Educational Specialist
Department of Entomology
Updated by: J.M. Diez April 2007
Hosts of the nigra scale include Anthurium, bamboo, coffee, cotton, croton, eggplant, fig, edible ginger, guava, macadamia, ornamentals, and pineapple.
Native to Africa, this scale has a cosmopolitan distribution throughout he world. Present in Hawaii since 1895, the nigra scale is present on all major islands except Lanai.
The nigra scale feeds from the phloem of the host plant and may be found on leaves or twigs containing chlorophyll. Damage due to feeding of an individual scale is small. However, when large populations are present, yellowing, defoliation, reduction in fruit set, and a loss in plant vigor may result.
This scale is believed to reproduce parthenogenetically, or non sexually. Females are able to lay viable eggs without fertilization by males. Males have not been found in this species, and populations are believed to be comprised solely by females.
Under laboratory conditions, generations of this scale were continuous when raised on potato sprouts at 75û F. One generation (egg to reproducing female) was completed in 45 to 60 days. Laboratory rearing on Annona and Citrus gave similar results.
Eggs are oval in shape. Just after being laid, the eggs are transparent with a shiny surface and turn pink in color in a few hours. Before hatching the eggs are a yellow orange color with two black spots that correspond to the eyes. Eggs are found protected under the body of the adult and hatch in 4 days.
There are three larval stages. Duration of the first, second and third stages are 16, 13 and 12 days, respectively.
The first larval stage individuals are transparent green at first and turn transparent yellow-pink once a feeding site has been selected. This stage is the only active larval stage. The larvae crawl rapidly for 1 to 6 days to disperse into neighboring trees and plants with a tendency to ascend towards new plant growth, although many remain close to the parent. After the larvae have attached themselves to the feeding site, waxy secretions form on the setae (hair) of the scale forming 4 white lines on the body.
The second stage larvae are colorless after emerging, turning opaque white two days later and darkening as they are exposed to natural light. These larvae are able to detach themselves to select a new feeding site if necessary but are generally stationary. During this stage, the scale begins to produce honeydew.
The third larval stage individuals are slightly larger in width and height than second larval stage individuals. There is also an increase in waxy secretions around their setae. They are white in color with a posterior dark spot corresponding to the anal plate. Honeydew is abundant and accumulates in transparent drops.
Adult females vary from dark brown to shiny black in color and measure up to 1/5 inch in length. Unweathered adults have delicate, flat plates of wax arranged in a row-like fashion over their body. Their overall shape on leaves is broadly oval and only moderately convex. On twigs, however, they become narrow, elongate, and relatively more convex. Size, form, and color of this pest varies with different hosts. A complete taxonomic description and comparison of individuals collected in different geographic regions is given by Ben-Dov (1978).
Females have a pre-oviposition period of approximately 37 days and an oviposition period of 70 days.
The first stage larvae are light sensitive and will move from an established feeding site if they find the area too bright.
Natural biological control is usually sufficient to keep populations of this scale at bay. Single tree or branch infestations may be cut and left on the ground for parasites to emerge from. Several natural enemies of the nigra scale are present in Hawaii. Parasites include Microterys flavus (Howard), Encyrtus kotinskyi (Fullaway), Encyrtus infelix (Embleton), Encyrtus barbatus Timberlake, Tomocera californica Howard, Scutellista cyanea Motschulsky, Coccophagus hawaiiensis Timberlake, Aneristus ceroplastae Howard, and Quaylea whittieri. Several general predators attack this scale, they include some beetles, butterflies and moths, flies, thrips, and mites. The nigra scale is also attacked by a fungus, probably Entomophthora pseudococci.
If natural control is insufficient in widespread attacks, trees may be banded to keep off attendant ants. Banding involves either painting or spraying a 1% Dieldrin on to the plant stem. Oil spraying using 10 pints of white oil in 40 gallons of water has also proven satisfactory.
There are no listing for Dieldrin as of April 2007.
Ben-Dov, Y. 1978. Taxonomy of the Nigra Scale Parasaissetia nigra (Nietner) (Homoptera: Coccoidea: Coccidae), with Observations on Mass Rearing and Parasites of an Israeli Strain. Phytoparasitica.
Chua, T.H. 1978. The Parasite Complex of Saissetia nigra in Malaysia. Entomophaga. 23(2): 195-201.
DeLotto, G. 1956. The Identity of Some East African Species of Saissetia (Homoptera, Coccidae). Bull. Ent. Res. 47: 239-249.
LePelley, R.H. 1968. Parasaissetia nigra. pp. 368-371. In Pests of Coffee. Longmans, Green & Co., Ltd., London and Harlow. 590 pages
Marin, R.L. and F.H. Cisneros. 1979. La Queresa Negra Del Chirimoyo: Saissetia nigra (Nietner) (Homoptera: Coccidae). Revista Peruana de Entomologia. 22(1): 103-110.
Zimmerman, E.C. 1948. Saissetia nigra (Nietner). pp. 324-328. In Insects of Hawaii. A Manual of the Insects of the Hawaiian Islands, including Enumeration of the Species and Notes on Their Origin, Distribution, Hosts, Parasites, etc. Volume 5. Homoptera: Sternorhyncha. 464 pages.