Dubas Bug Ommatissus Lybicus Case Study

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1.2 Dubas bug Ommatissus lybicus
1.2.1 Taxonomy and distribution
Ommatissus lybicus is belonging to the family Tropiduchidae which distributed mainly in tropical regions and comprise about 330 species. Most species of this family are greenish, yellowish to a brownish colour and 5-7 mm long. In addition, Tropiduchidae has clear forewings, which are longer than their body. Tropiduchidae is common in tropical forests and its genus Ommatissus is distributed in the eastern hemisphere. Unlike the other palmivorous species of Auchenorrhyncha, which are associated with multiple palm species, the genus Ommatissus spp. seem to be more restrictive in their host ranges of palms, produce more honeydew and cause remarkable direct damage to palms through oviposition and feeding (Howard, 2001).
O. lybicus is limited to P. dactylifera (monophagous insect) and found in almost all date palm
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lybicus nymphs are undergone five instars before reaching the adult stage. The number of the waxy caudal filaments clusters used to distinguish between the five nymphal instars (Al-Kindi et al., 2017; Al-Khatri, 2011; Al Sarai Al Alawi, 2015; Hussain, 1963; Howard and Wilson, 2001). Caudal filaments numbers in each nymphal instar are consistent and increase after each nymphal moult (Al Sarai Al Alawi, 2015). In addition, nymphs can jump for a short distance when disturbed (Howard and Wilson, 2001).
First nymphal instars are 0.8 - 1.25 mm long and pale gray in colour. They characterize with obvious dark patches on both sides of the thorax and abdomen segments. The first instars have no lines on the thorax and abdomen dorsal surface.
Second nymphal instars are 1.3 – 2.25 mm long. Two lines of dark brown spots formed on the thorax and abdominal dorsal surface.
Third nymphal instars are 1.6 - 2.68 mm long. The dorsal surface of the thorax and abdomen characterized by two longitudinal lines.
Fourth nymphal instars are 2.18 - 4 mm long. They characterized with three lines on both thorax

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