Predaceous and parasitic, ground-dwelling arthropods in different ecosystems in Western Saudi Arabia

الملخص EN

Populations of predaceous and parasitic ground-dwelling arthropods have been investigated in three ecosystems: a) natural ecosystem of uncultivated land, b) a continuously cultivated vegetable agroecosystem and c) a permanent agroecosystem of date palm-citrus orchard during an 8 months period starting October 1985 through May 1986 by pitfall trapping to determine their species composition and abundance.

Araneae, For-micidae, Histeridae and Carabidae were consistently the most abundant of the predaceous-parasitic arthropod complex.

From data analysis Chi square (X2) the ratio of the arthropod taxa present in the three ecosystems showed high significant differences at 1% level of probability.

The composition of this complex did not vary in the three ecosystems, but their respective numbers have declined at the onset of winter (November to December).

True Spider (Araneae) represented a distinct group averaged 39.4% and one family of them, the Lycosidae, has amounted for 72.'1% of all true spiders, harvestmen and sunspiders put together.