Borage (Borago officinalis L.) is anticipated as a banker plant in strawberry greenhouses to adopt integrated aphid management, because borage has a stimulatory influence on parasitoid wasps attacking aphids. However, before actually using borage, we had to answer the following question: will borage become a hotbed for spider mites? To investigate this, host plant suitability and acceptance by 18 tetranychid mite species were tested on borage and strawberry leaves. The mites were two Panonychus species, two Eotetranychus species and 14 Tetranychus species, including the green and red forms of T. urticae that were counted as separate species. Borage appeared an unsuitable host, because females of all 18 mite species did not lay eggs, females of most species could not survive for more than 5 days, and larvae of all 18 mite species did not develop to nymphal stages on borage. Conversely, strawberry was a suitable host for 13 of the 18 spider mite species: females laid eggs and about 90% of larvae successfully reached adulthood. Thus, these13 species have the potential to become pests of strawberry. Offering female spider mites the choice between interconnected borage and strawberry leaf discs, (1) most females moved from borage to strawberry except for the two Panonychus species and E. asiaticus, and (2) few females moved from strawberry to either borage or strawberry. Consequently, it is highly unlikely that borage will become a hotbed for any of the spider mite species.

The population fluctuations of Tetranychus urticae Koch and the associated phytoseiid mite, Euseius scutalis (A.-H.) on three soybean cultivars at Gharbia Governorate were studied during two successive seasons of 2015 and 2016. The results indicated significant differences in the T. urticae infestations through 2015 and 2016 seasons. Giza 35 variety harbored the highest infestation recorded 552.56 and 440.5 motile stages/10 leaflets for the two successive seasons, as compared with Giza 21 and Giza 83 varieties. Giza 21 variety was the most tolerant one recorded 130.38 and 174.88 motile stages/10 leaflets for two successive seasons. Significant positive correlations occurred between the T. urticae population and E. scutalis in all soybean varieties. The predatory mite was the main important predator for suppressing population density of T. urticae population during the two successive seasons. The insignificant positive effect of maximum and minimum temperatures on the population of T. urticae infested the three soybean varieties during 2015 and 2016. The combined effect of the tested weather factors (max temp., mini temp. and R.H. %) and the plant age together on T. urticae population were studied. The plant age and phenology were more effective on T. urticae population as compared with the weather factors.

Some biological aspects of Tetranychus urticae Koch on three soybean cultivars (i.e., Giza 21, Giza 35 and Giza 83) at three constant temperatures of 22, 26 and 30°C; 65% R.H. and 16:8 L: D photoperiods were studied. The results indicated that, T. urticae successfully developed on all experimental soybean cultivars at the three constant temperatures. The life cycle of T. urticae was the longest at 22°C followed by 26°C, than 30°C. The longevity of T. urticae female were 18.18, 18.88 and 19.18 days at 22°C, while the shortest periods were 13.65, 13.85 and 15.30 days on Giza21, Giza84 and Giza35, respectively. Significantly differences occurred between all stages at the three levels of temperatures. The highest fecundity and daily rate at 30°C was 95.65 eggs/female and 8.72 eggs/♀/day, while the lowest was71.58 eggs/female and 5.33 eggs/♀/day at 22ºC. Significant differences occurred between the three varieties diets as fecundity was the highest on Giza35 and the lowest on Giza21. These results indicated that, soybean Giza35 was more susceptible to the infestation by spider mite, while Giza21 was more tolerance, whereas Giza83 was in between. The lowest threshold temperature (t 0 ) to different stages of the mite, T. urticae were recorded as: 14.26, 3.44, 6.34, 11.32, 7.93, 11.32, 9.85 and 4.66 for egg, larva, protonymph, deutonymph, immature, life cycle, generation and life span for the mite females, respectively. Whereas, T. urticae female required 135.4 DDUs to complete its development (egg to adult).