*4.1.1 Taxonomy*

Chinch word in Spanish means Pest. The family lygaeidae genus Blissus which contain chinch bug species, yet the taxonomy of the genus is poorly understood. Chinch bug, though native of tropical America but extended its range to the world. It subdivided into two species *Blissus leucopterus* and subspecies *B. leucopterus leucopterus* which are known as Chinch bug and hairy chinch bug respectively. Before

and in 1831, the original species combination was Lygaeus leucopterus Say [90] The genus name was replaced in 1835 burmeister. The species name combination of two word leuco which means lack of color and pterus means wings [91]. However, it belongs to order hemiptera (suborder: Heteroptera) and family Lygaeidae. Sub species are *B. leucopterus leucopterus (*Say*), B. leucopterus hirtus* (montandan).

#### *4.1.2 Distribution*

Chinch bug, *B. leucopterus* (say) native to the new world, found throughout Americas south as well as the North America region. Chinch bug spread Virginia to Georgia extending to south Dakota and Texas in east and west respectively [92].

#### *4.1.3 Biology*

*B. leucopterus* passes two generations per year, a complete life cycle occurs in 30–60 days. Eggs are elongate-oval and rounded at one end, truncate shape at the other end. The eggs are whitish on the first days, turn yellowish after a few days and become red at time of hatching. Female of chinch bug lays eggs in short rows on root, stem, leaf sheath or on soil near the plant [92]. Eggs rate laying by females are 15–20 per day over 2–3 week, producing upto 500 eggs a single female. Eggs are hatching 16 days at 27°C and 8 days at 31°C [93].

There are five nymphal instars with 5, 6, 5, 4, and 6 intervals during each instar when reared at 29°C, under field conditions, the development time may be extended. The normal development time is 30–40 days in normal and may be extended in 60 days. Identification of nymph in early stages, head and thorax are brown, legs are yellowish. These colors are darker as the mature nymph, so the mature nymphs are blackish in color. There are yellowish and whitish colors on the first two segments of abdomen. Wing pads become visible in 3rd instars. Nymphs prefer sheltered locations to feed and aggregate on the stem near the main stem of the plant [92].

Adults are blackish in color; wings nearly attain the end of abdomen and are white in color with blackish spots found near the center. Measurements of adults are 3.5 to 4.5 mm in length.

#### *4.1.4 Damage*

Host of chinch bugs consist solely of family gramineae, but also include other grasses and plants. Chinch bug is a plant feeding insect, causing reddish color at the site of feeding and death of the plant. Plant growth can be stunted, or dead by a large number fed on plants. The losses by chinch bug were estimated at 19 million dollars in 1989 [94].

#### **4.2 Wheat aphid**

#### *4.2.1 Taxonomy*

Aphids evolved in Carboniferous period about 280–300 million year ago [95, 96] Many species of aphid attack on wheat crop, three major aphids pest are *Myzus persicae* (Sulz.), *Sitobion avenae* (F.) and *Schizaphis graminum* (Rondani). Sulzer was the first who described *Myzus persicae* in 1776 as *Aphis persicae.* Species have many synonyms which are listed by Borner [97]. The Aphid genus of Myzus belongs to the largest tribe of aphid Macrosiphini [98], which contains fifty five species. *M. persicae* make a species complex which describes as a separate species *M. nicotanae*.

Order: Hemiptera. Suborder: Sternorrhyncha, Family: Aphididae, Genus: Myzus, Sitobion and Schizaphis, Species: *M. persicae, S. avenae and S. graminum.*
