Use Of The Teflubenzuron Alone And Combined With Metarhizium Anisopliae And Phenyl Aceto Nitrile As Control Agent Against The Desert Locust, Schistocerca Gregaria (forskal)

Abstract

The efficacy of the Insect growth regulator (IGR) 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) alone, and 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. The results indicated that, in season 1, when using Nomolt 450 ml, 225 ml, 112.5 ml, 56.25 ml/ha, 100% mortality was achieved in 20, 18, 20 and 21 days after treatment, and the same percentage of the mortality was achieved in 14, 14 , 15 and 16 days after treatment, respectively in season 2. 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 in the 1st season. The same trend of mortality was recovered in the 2nd season. Tests in bomas using barrier treatment in the 1st 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 1st, 6th, 12th and 24th day after treatment respectively. Percentage mortality of 78.5, 68.5, 74 and 61.5 were achieved in the 2nd season. The Nomolt alone revealed a clear negative impact on the feeding rate of nymphs. The feeding rate decreased after 3 days of treatment and stopped altogether on the fifth day. The nymphs treated with IGR combined with the pheromone PAN stopped feeding on the fourth day after treatment; however, they stopped feeding on the third day after being treated with Nomolt combined with GM.