Relationship between Moroccan locust (Dociostaurus maroccanus) population densities and rangeland plant properties in Golestan province (Case study: Qaraqar-Bozorg rangelands)

The Moroccan locust (Dociostaurus maroccanus Thunberg) is one of the most important species of locusts in Iran and many parts of the world, which causes great damage to pastures and agricultural products every year. Since a main part of the life cycle of this insect is spent in pastures, recognizing the relationship between locusts and plant properties are important in the rangeland management and locust control programs. The Qaraqar-Bozorg region in Golestan province is one of the centers of Moroccan locusts, parts of which are attacked by this pest every year. The present study - It was done in April 2019- investigates the relationship between Moroccan locust density and biophysical properties of the main vegetation types in this region. Moroccan locust densities were estimated using randomly-systematic plotted samples of 1 square meter at three sites of (without, medium and high locust density) in Qaraqar-Bozorg rangelands. Plant properties based on main vegetative forms (grass and forbs) including canopy cover percentage, density and their heights were estimated in each plot. The correlation between quantities of main vegetative forms and locust density was then tested using Pearson correlation coefficient. The results showed a significant positive correlation between locust densities and the canopy cover percentage, density and height of the grass vegetative forms (with coefficient of determinations of 0.41, 0.45 and 0.34, respectively). Results also showed that Moroccan locust prefers habitats that grasses are dominant. Care should be taken in interpreting the results merely based on the preference of vegetation types by Moroccan locust. It seems the combined effect of environmental factors in dominated grass habitats such as soil texture, moisture availability and shade cast might have an effect on the preference of grass habitats by Moroccan locust in the study area. This results can be useful in planting projects or rangeland improvement, as well as in control programs of Moroccan locust and in finding highly infested areas with this pest.