الفهرس 
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Abstract
Survey studies indicated that broad mite, Polyphagotarsonemus latus occurred frequently on squash while spider mite, Tetranychus urticae was abundant on green bean, pea and cucumber in Mansoura district during 2009-2010. Survey cleared that P. latus started to appear on squash plants in late August and gradually increased and reached its peak in the 3rd week of September, then gradually decreased until the end of the growing season in late October. Concerning bean plant, T. urticae started increasing from the 3rd week of April and reached its highest rate of infestation at the end of May. After that, T. urticae population gradually decreased in the 1st week of June and started again to build up its population and reached its second peak end of June. Mite infestation on pea plant started smoothly from the 1st week in January and increased gradually on 11th February then decreased until March. The same trend of spider mite infestation was similarly observed on cucumber growing from April to June 2010 and the infestation increased to reach the highest rate in early June. After that, mite incidence declined end of June.
Also, toxicological studies cleared that under field conditions, cyflumetofen 24% SC was the most effective acaricide against mites, T. urticae and P. latus where it caused 98.25 % and 99.93% mortality 10 days after treatment, respectively. Furthermore, results proved that under laboratory conditions, LC50 and LC25 of cyflumetofen reached their highest efficiency against T. urticae females 10 days after application causeing 85.71% and 80.95% mortality, respectively while LC12.5 needed for 11 days to kill an average of 66.67% of T. urticae females. The results clearly indicated that LC50 and LC25 completely inhibited egg production after 8 and 10 days post-treatment, respectively. Concerning mite females treated with LC12.5, it steadily reduced female fecundity until the 10th day after treatment and then tested females began to lay more eggs in comparison with the higher concentrations.
Biological studies on predatory mite Phytoseius plumifer resulted that feeding on T. urticae accelerated the development of P. plumifer. Life span of males reached 30.82 and 23.18 days when fed on broad mite and spider mite during which they consumed an average of 6.60 and 5.46 prey/day. Concerning P. plumifer females, data showed that life span took 41.6 and 34.8 days, during this period each female consumed daily 9.78 and 12.70 individuals of broad mite and spider mite, respectively. In addition, the present study proved that the spider mite T. urticae is a preferable food during oviposition period in comparison with broad mite P. latus, where oviposition period lasted 13.4 days during which each female consumed an average of 253.5 spider mites to produce 23.85 eggs. These values significantly decreased when female mite fed on broad mite where it fed on 242.1 mites as well as its egg deposition declined to 18.90 eggs, respectively. Concerning life table parameters, predatory mite, fed on broad mite and spider mite, gave the intrinsic rate of natural increase (rm) values of 0.19 and 0.23 female offspring/female (female-1day-1), respectively. The finite rate of increase ( erm =λ) of P. plumifer, which was subjected to broad mite as a prey was reduced by 3.97% from 1.26 to 1.21 eggs/female/day (day-1) when it was fed on spider mite and gave a shorter generation time as well as doubling time comparing to P. latus as food source. Moreover, results indicated that crowding is the key factor affecting food consumption of the predatory mite P. plumifer fed on either broad mite or spider mite, were there was a negative effect of crowding on predator feeding capacity. Approximately 87.1% and 87.3% of the differences in prey consumption of P. plumifer directly resulted by its crowding factor (R2= 0.871 and 0.873 for a diet of broad mite and spider mite, respectively).