Use of teflubenzuron alone and combined with Metarhizium anisopliae and Phenylacetonitrile as control agent against the desert locust, schistocerca gregaria (Forskal) (Orthoptera: acrididae)

The efficacy of the Insect growth regulator (IG R) teflubenzuron (Nomolt 50 ULV) was evaluated against desert locust (DL) nymphs (3rd and 4th instars) during two seasons (2008 and 2009). All experiments were carried out under semi-field conditions, on irrigated plots planted with millet, and large cages (2x2x1m) and bomas (2x6x1m) were erected to enclose the test insects. The IGR was applied by means of a battery driven hand held (Micro ULVA) sprayer either as direct spray on the nymphs or as a simulated barrier treatment. The impact of the IGR on the feeding rate of the nymphs was investigated as well. The IGR was tested at the recommended dose (450ml/ha), and at fractional doses (225, 112.5 and 56.25ml/ha) in combination with Metarhizium anisopliae (Green Muscle®) at 50g/ha and the pheromone Phenyl Aceto Nitrile (PAN) 98% at 10ml/ha. Diesel was used as a dilutant in all formulations. Nomolt 450 m/ha resulted in 100% nymphal mortality in 20 days after treatment. The fractional doses of the IGR combined with the pheromone PAN, proved to be effective in the manipulation of nymphs, 100% mortality was obtained in 21, 20 and 21 days after treatment, in both seasons of the study. The fractional doses of the IGR combined with Metarhizium GM resulted in 100% mortality within 14 days of the treatment. Tests in bomas using barrier treatment in the 1 st season of the study revealed that the recommended dose of Nomolt applied on the nymphs resulted in 72.5, 88.5, 89 and 53% mortality after the 1 st , 6 th , 12 th and 24 th day after treatment respectively. Percentage mortality of 78.5, 68.5, 74 and 61.5 were achieved in the 2 nd season. The Nomolt either alone or in combined with PAN and GM revealed a clear negative impact on the feeding rate of nymphs.

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