Comparison between the Effect of Nano Chitosan and Fabcomic Insecticide against Tetranychus urticae (Acari: Tetranychidae)

The journal of Toxicology and pest control is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the interaction between insects and their environment. The goal of the journal is to advance the scientific understanding of mechanisms of toxicity. Emphasis will be placed on toxic effects observed at relevant exposures, which have direct impact on safety evaluation and risk assessment. The journal therefore welcomes papers on biology ranging from molecular and cell biology, biochemistry and physiology to ecology and environment, also systematics, microbiology, toxicology, hydrobiology, radiobiology and biotechnology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.


INTRODUCTION
Tetranychus urticae Koch is a notorious pest of economically important agricultural crops as well as ornamental plants (Navajas, 1998).It has been reported to attack about 1200 species of plants (Zhang, 2003), of which more than 150 are economically important (Jeppson et al., 1975, Xie et al., 2006).It causes damage to sweet corn, beans, peas, hops, grapes, deciduous fruit trees, strawberries and many other vegetables, flowers and ornamental plants (Johnson and Lyon, 1991).Commercially available synthetic acaricides are usually cost a lot and also needed to be imported for use by farmers.They also tend to have detrimental effects on the environment and can be hazardous to humans.These negative effects have resulted in raising interest in natural materials which are assumed to be safer than females synthetic pesticides (Yanar et al., 2011).
Chitosan (CS) is a natural polysaccharide.It is not only pollution safe but nourishes the plant and less costly too.Chitosan (C6H11NO4) n, the N-deacetylated derivative of chitin, is preferred due to its, antioxidant, biodegradability, biocompatibility, antimicrobial, and non-toxic properties (Dash et.al., 2011) as well as being a kind of the waste of fish and crustaceans, which are abundant in Egypt.
The present work was aimed to evaluate the comparison between nano chitosan and the specific acaricide, Fabcomic, on T. urticae.

Preparing the Stock Solution of the Tested Materials:
Convenient stock concentrations of each material were prepared based on the tested material weight and the volume of the distilled water (w/v).Four diluted concentrations for each material were used to draw the LC-P lines.Three replicates were used for each concentration.

Toxicity Test:
The toxicity of nano chitosan and the Fabcomic acaricide were tested against T. urticae.Thirty newly emerged adult females were transferred to the lower surface of castor leave discs (2.5 cm diameter) placed separately on moist cotton wool in Petri dishes.Each petri dish contains three replicates, ten individuals in each replicate.Each acaricide had four concentrations which were sprayed on the individuals.Mortality was recorded for 3 days after treatment.The mortality percentage was estimated and corrected according to Abbott's formula, 1925.LC50 values were determined using the appropriate analysis statistical method of Finney, 1971.Equation: Sun, 1950 (to determine LC50 index) Toxicity Index for LC50= LC50 of the most effective compound X 100 LC50 of the least effective compound

The Effect of Nano Chitosan and Fabcomic Acaricide on Adult Female of Spider Mite, Tetranychus urticae Koch:
The data in Table (1) indicated that nano chitosan and fabcomic acaricide caused a high mortality proportion on T. urticae specially in high concentrations.These results were in agreement with El Kady et al. 2007 andCampos et al.2018.

Lethal Concentrations of Nano Chitosan and Fabcomic Acaricide on Adult Female of Spider Mite, Tetranychus urticae Koch:
Table (2) and Fig.
(1) demonstrated that fabcomic was more effective than nano chitosan, with LC50: 0.10 ppm and 801.04 ppm, respectively.LC90 value was 1.66 ppm and 5746.09ppm for fabcomic and nano chitosan, respectively.The toxicity index was 100% for fabcomic while it was 0.013% for nano chitosan.The slope values were 1.06 and 1.50 for fabcomic and nano chitosan, respectively.Although fabcomic acaricide was more effective than nano chitosan in control of T. urticae, it's harmful for all living organisms including plants.While nano chitosan is originated from remains of fish and skeleton of sea organisms so, it's more save on humans, animals, fish and plants and also effective in controlling T. urticae.These results also were in agreement with Ahmadi et al. 2017.