Geographical distribution: Cosmopolitan, wherever the mealybug hosts occur.
Morphology: About 2-3 mm in length, body yellow-red, the abdomen in some species darker. Legs and distal antennal segments dark.
Hosts: Various mealybugs.
Life cycle: Species of Leptomastix are solitary endoparasitoids of mealybugs. They insert a single egg into the host, develop therein in 3-4 weeks, the mealybug meanwhile becoming a brown mummy. Adults may live for several weeks, feeding on honeydew or nectar.
Economic importance: Several species are used in commerce to control pestiferous mealybugs. In the Middle East the main species include:
Leptomastix algirica Trjapitzin
A Mediterranean species that attacks several mealybugs, including Pseudococcus cryptus and Pseudococcus longispinus. Its eggs were encapsulated in the bodies of Planococcus citri and other species of Planococcus. In contrast to other species of Leptomastix, it has almost-black wings, which impart a dark aspect to its body.
Leptomastix dactylopii Howard
A widely distributed species that occurs in or was introduced into most regions, and attacks about 20 mealybug species. The females prefer third-instar nymphs and young adult females as hosts. The adults live 3-4 weeks and fecundity comes to 60-100 eggs/female, depending on available nutrients. It had been used in Turkey against P. citri since 1970, and has completely controlled this pest in Indian guava orchards as well as in Australian citrus groves. In Egypt, where it was reared from Maconellicoccus hirsutus and Planococcus ficus, parasitization rates were only up to 8%. In some mealybug hosts the parasitoid’s egg is encapsulated. When attacking P. citri, the color of the host plant (Coleus blumei Benth.) affected the size, fecundity and survival of L. dactylopii, being larger, higher and better on red cultivars than on green ones. The coccinellid predator Nephus kreissli Fürsch and Uygun could not feed on mummified P. ficus in which L. dactylopii was developing. The systemic Flonicamid and an insect growth regulator had little effect on L. dactylopii.
Leptomastix flava Mercet
This species occurs in southern Europe and North Africa. In Egypt it attacked up 27% of Nipaecoccus viridis.
Leptomastix nigrocoxalis Compere
This species is widely distributed in Africa and Asia. In Egypt it attacks N. viridis (8.5-21% parasitism) and M. hirsutus (2.5-13% parasitism).
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