*2.3.2 Distribution*

The wheat armyworm is present in various wheat growing agro-ecosystems from Asia to Australian continent between 45 north and 45 south Latitude and 60 east to far 170 West Longitude. It is found in 27 countries including China, Japan, Pakistan, and India also in Pacific islands from tropics to temperate climatic regions [14].

### *2.3.3 Biology*

The fertile females lay maximum eggs from 500 to 900, spherical and milky white in color to approximately 2000 eggs. The eggs are laid in clusters on or underside the young seedlings or in soil. The eggs will hatch in 2–7 days after that larva emerges and lasts long for 14–22 days. The mature larva possesses green to pink color having greenish to brownish black stripes on the entire body length [15]. Pupation is usually done in soil but can be done under dry leaves or fresh stubbles or fresh tillers as well. The pupae are shiny brownish yellow in color and last upto13 days. Thus, the whole span lasts in about 35–40 days which may repeat multiple times in each year.

#### *2.3.4 Damage*

*M. separata* Walk. damages the yield losses as this is influenced by the environmental conditions of the area and the stage of wheat crop. Innovations in farming

#### *Current Trends in Wheat Research*

systems such as introduction of high yielding cultivars, balanced fertilizer use and crop rotation of wheat increased the chances of high yield loss by this pest [16]. Severe attack must lead to decreased productivity by reduction of quantity as well as quality of grains [17]. Due to its polyphagous nature, it causes severe economic losses in crop production worldwide [18]. The young larvae feed on younger plants and due to its short life cycle results in heavy infestations with much heavier loss to young tillers [19]. In the past, loss due to *M. separata* Walk.was recorded as 10–30% in Wheat crop [20]. With every increase of 1% in leaves consumed by the armyworm decrease the yield by 0.07–0.88 g per plant from booting to panicle stage.

During the young vegetative stage of wheat plant, the damage is more prominent with extensive defoliation. Young larvae may feed at lemma and palea of young grain as well as male part anther of mature flowers. The larvae cut the young seedlings so often the damage is restricted to a single part of the field. During the grain formation stage, the larvae feed upon the panicles from the basal part of the plant causing it to bend downwards and sometimes the plant may fall down.
