Field morphological identification of the most important Acrididae nymphs of cereal crops in Iran

Abstract

The order Orthoptera, including locusts, grasshoppers, mole crickets, crickets and bushcrickets, are generally herbivores. With large-scale and single-crop agriculture development, some locusts and grasshoppers appeared as pests and sometimes caused famine and crisis. The plateau of Iran is the origin of many cereal cultivars. Since some morphological characters, particularly the male internal genitalia in nymphs do not differentiate enough for confident diagnosis; the classical morphological identification of grasshoppers is largely based on the characteristics of adults. However, identifying the nymphs is very important in the field from the economic point of view, because most crop loss is due to the nymphal damage. Although accurate molecular determination is possible even in the egg stage, this technique is costly and specialized. Thus, providing cheaper and simpler approaches have rational perspectives. Our studies showed that some morphological features in nymphs could be practised at a genus-level field identification, none of the important grasshoppers related to wheat cultivation in Iran has apterism, and only the macroscopic characteristics of nymphs of two ages before maturity provide the necessary accuracy for field identification. Therefore, from 2019 through 2021, morphological characteristics of developing organs that could be informative for taxonomy in the late-stage nymphs were investigated in 362 nymphs belonging to 22 genera of 8 subfamilies out of 2 families. As a result, some 35 most conservative characters and 79 character-states were extracted. Afterwards, an illustrated key for field genus identification was prepared based on a sort of data. Education and extension of these filed identification outputs can avoid wasting time and money and lessen pollution of the environment with hazardous chemical agricultural pesticides before any control operation.