Susceptibility of three squash cultivars to the two spotted spider mite, tetranychus urticae (Acari : Tetranychidae)‎ infestation in relation to phyto-chemical components of the leaves

الملخص EN

The field experiment was conducted to evaluate the relative susceptibility of three squash cultivars, Cucurbita pepo L.

(Mabroka, Brencesa and Eskandarani) against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) during two successive years 2016 and 2017 in Balaktar and Om Saber villages, Behera Governorate.

Also, it was carried out to study the effect of the morphological leaf characteristics and the chemical components (phenol, protein, chlorophyll and carbohydrate) of the three previously mentioned squash cultivars and clarified the resistance of the pest infestations.

Obtained results showed that there was no significant difference in eggs or motile stages or the total numbers of spider mite infestation on the three cultivars (LSD; P > 0.05).

However, Mabroka cultivar was the most resistant cultivar to the spider mite pest as its leaves harbored the lowest mean numbers (LSD; P < 0.05) and produced higher average of yield than that of Eskandarani cultivar in both villages, followed by Brencessa cultivar which occupied a moderate mean numbers of the spider mite in spite of produced higher total of yield production than that of Eskandarani cultivar.

Which suffered the highest infestation of the spider mite population during both seasons, also its production was significantly the lowest average yield production (P < 0.05) in both locations.

The morphological leaf characters, the number of in the lower surfaces were different in their shapes, length and number of setae for Mabroka, Brencesa and Eskandarani, which in 1 mm were 29, 39 and 61 setae, respectively, the results of chemical analysis of leaf component after pest infestation indicated positive relationships in case of total phenol (r = 1) for the three cultivars.

While the amount of protein, chlorophyll and carbohydrates were significantly decreased and their (r) values were (-1) in the three cultivars.

It could be classified to three degrees, the severe infestation as represented by (Eskandarani), the moderate infestation (Brencessa) and the last of low infestation (Mabroka).

It is concluded that growing the Mabroka cultivar better than the other two tested cultivars.