APPLICATION OF TOMATO LEAVES EXTRACT AS PESTICIDE AGAINST APHIS GOSSYPII GLOVER ( HEMIPTERA : APHIDIDAE )

Ghada E. A. 1 , Manal E. A. Elshaier 2 , Amal E.M. 1 and Hala E. M. 2 . 1. Plant Protection Research Institute, Dokki, Giza, Egypt. 2. Faculty of Science, Al-Azhar University, Cairo, Egypt. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


Introduction
Tomato (Lycopersicon spp.) is economically one of the most important vegetables (Polston and Anderson, 1999). Cotton aphid (Aphis gossypii Glov.) is one of the basic pest of tomato. It is a direct plant-sucking pest and it can cause serious problems on leaves, stems and fruits (Sharma and Joshi, 2010). It also causes direct damage by secreting honeydew that causes development of sooty-mould (Blackman and Eastop, 2000).Chemical control tactics have been the primary method for managing infestation, but this strategy has become less effective due to development of insecticide resistant population (Siebert et al., 2012). Pesticides produced from natural products have been recently attracting the attention of many scientists to avoid the problems caused by synthetic compounds. They are deeply interested in their chemical constituents and biological properties (Abou-Yousef et al., 2010).Tomato is a good source of phenolic compounds, pigments, antioxidants and other nutrients, these compounds prevent oxidative changes in cell by reducing the level of free radicals . The aim of this study was to determine the effect of tomato leaves extract on the cotton aphid, Aphis gossypii and made GC/ MS analysis to tomato leaves.

ISSN: 2320-5407
Int. J. Adv. Res. 5(4), 286-290 287 Material and methods:-Insects:-Tomato leaves carrying A. gossypii were collected from the unsprayed farm of Agriculture College, Mansoura University (Dakhlia, Egypt). The leaves were kept in jars at 27± 2 O C and 65± 5% RH. The colony was maintained for two generations before the beginning of the tests. Then, newly born nymphs of A. gossypii were placed, separately on tomato leaves in plastic Petri dishes (10 cm. in diameter). Each dish was covered with muslin for aeration and the tomato leaves were put on the bottom of the dish (Mahdi and Sahragard, 2012). Whenever leaves appeared discolored, they were replaced with fresh ones.

Preparation of Plant Sample and Extraction:-
Leaves of tomato plant, 961 sorts, were left to dry at room temperature for one month then the dried leaves were grinded into fine powder. Powder was soaked in a mixture of hexane, acetone and ethanol solvents of equal proportion (1:1:1) in a flask for about one week. Finally, the flask was shake in a shaker and its contents were filtered. The solvents were evaporated under reduced pressure; the resulted crude extract was weighted and kept in deep freezer until use.
Preparing the Stock Solution of the Tested Plant Extract:-Convenient stock, concentrations of tomato extract, was prepared on basis of the tested plant weight and the volume of the distilled water (w/v) in the presence of tween 80(0.1%) as emulsifier. The stock concentrations were kept in glass stoppered bottles and stored under refrigeration. Such stock solutions were prepared periodically. Four diluted concentrations for the plant extract were used to draw the LC-P lines. Four replicates were used for each concentration.

Method of application:-Spray method:-
The adults of the aphid were used for application. Four concentrations were used as well as four replicates for each concentration. 10 individuals of aphids for each replicate were applied to estimate the mortality line. Different concentrations were sprayed directly on the aphids. The concentrations used were 250, 500, 750 and 1000 ppm. The percentage of mortality was recorded after one, three, five and seven days and the data were corrected relatively to control mortality (Abbott, 1925). LC 50 values were determined using Probit analysis statistical method of Finney, (1971).
Chemical analysis:-GC/MS analyses were conducted in Central Agricultural Pesticide Laboratory. They used an Agilent 6890 gas chromatograph equipped with an Agilent mass spectrometric detector, with a direct capillary interface and fused silica capillary column PAS-5 ms (30m x 0.32mm x 0.25 μm film thicknesses). Sample was injected under the following conditions. Helium was used as carrier gas at approximately 1.0 ml/ min., pulsed split less mode. The solvent delay was 3 min. and the injection size was 1.0 μl. The mass spectrometric detector was operated in electron impact ionization mode with an ionizing energy of 70 e.v. scanning from m/z 50 to 500. The ion source temperature was 230 o C. The electron multiplier voltage (EM voltage) was maintained 1650 v about auto tune. The instrument was manually tuned using perfluoro tributyl amine (PFTBA). The GC temperature program was started at 60 o C (2 min.) then evaluated to 300 o C at rate if 5 o C/ min. the injector temperature was set at 280 o C, respectively. Wiley and Wiley NIST mass spectral data base was used in the identification of the separated peaks. Table (1) demonstrated that, although the extract concentrations were low, the mortality rate of the adults of Aphis gossypii was high and when the concentrations increased, the total mortality increased. These results were in agreement with Hansson et al. (2012) which proved the effectiveness of ethyl ester oil on Myzus persicae. However, Table (2) and Fig. (1) Table (3) and Fig. (2) and arranged according to their retention times and their percentage composition. These compounds comprise 89.08% of the total composition. Phytol was the most abundant compound (16.03%), followed by hexadecenoic acid, ethyl ester (6.14%), ethyl 9, 12, 15-octadecatrienoate, alpha-linolenate (6.06%),3,7-dimethyl-2, 6-octadienal (5.03%), Docosane (4.97%), 2-Pentanone, 4-hydroxy-4-methyl (4.73%), Tetracosane