First report of morphometric identification of Spodoptera frugiperda J.E Smith (Lepidoptera: Noctuidae) an invasive pest of maize in Southern Sindh, Pakistan

Abstract

Invasive species always pose a serious threat to agriculture and cost billions of dollars in terms of reduced production and productivity. The recent preliminary survey in a few districts of southern Sindh, Pakistan showed an apprehension of the entry of one more new invasive pest belonging to genus Spodoptera is known as Fall Armyworm (FAW), S. frugiperda (J.E. Smith) in April 2019. The identification for confirming this alien pest was made employing morphological characters. The males were dissected to study genitalia. The microscopic study revealed that male genitalia of the collected species had a single lobe of coremata which is the main identification of FAW. The wing characteristics showed that the males had dark gray and brown shaded mottled forewings with conspicuous triangular white spots at the tip of the wings. The forewings of females were less distinctly marked except few faint grayish brown markings. There were six larval instars and the best identifying feature of the FAW in mature larval stage (5th-6th instar) was a set of four large rectangular spots on the upper surface of the second last segment of body and the face of larvae with obvious mark of inverted white colored “Y” shape. In morphometric, we measured the head capsule of each larval instar ranging 0.3-2.6mm in length and the larvae about 2-33.08mm. The pupa was reddish brown in color, 14-18mm in length and about 4.5mm in width. The present study confirmed the presence of S. frugiperda which requires an immense attention to make an integrated pest management strategy against it.