Efficacy of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against Uvarovistia zebra (Orthoptera: Tettigoniidae) and Eurygaster integriceps (Heteroptera: Scutellaridae)

PhD Thesis ; The potential for the control of insect pests by entomopathogenic fungi has been studied for decades, and Metarhizium anisopliae and Beauveria bassiana are the best known of these entomopathogenic fungi. In this study the pathogenicities of B. bassiana DEBI 001 and M. anisopliae 715C obtained from the Iranian Research Institute of Plant Protection were evaluated for the first time against a long-horned (tettigoniid) grasshopper Uvarovistia zebra. Uvarovistia zebra is a univoltine grasshopper, distributed on the southern slopes of the Alborz Mountains in the north of Qazvin province in Iran. In some years, following good conditions for population growth, they can invade and damage field crops, and rangeland grass. Initially the efficacy of the two fungal isolates was assessed using topical application and ingestion. Experiments were carried out in the laboratory with field collected U. zebra to determine the effect of the fungi on food consumption by and mortality of the insect. Both fungi caused significant mortality of U. zebra by both contact and ingestion and both caused a significant reduction of food consumption and faeces production by the insects. The effect of fungal spore formulations in oil or water on lettuce discs was evaluated. Both oil and water formulations had lethal effects on U. zebra nymphs, but the spores formulated in oil on lettuce discs were more effective than those in water. Pathogenicity of the fungi was also evaluated against the Sunn pest Eurygaster integriceps. Experiments were conducted in the laboratory with different nymphal instars of E. integriceps to determine the relative susceptibility of nymphal instars and adults to the fungal isolates. Results showed that the fifth-instar nymph was the most susceptible with 60% and 46% mortality caused by B. bassiana and M. anisopliae respectively. The viability, mycelial growth and conidia production of the B. bassiana and M. anisopliae isolates preserved in different storage media were assessed. Assessments were done before ...