A laboratory study revealed that females of the phytoseiid mite, Amblyseius swirskii Athias-Henriot, fed on protonymphs of their own species or of other predatory mites i.e. Agistemus exsertus Gonzales and Euseius scutalis Athias-Henriot exhibited a marked decline in their fecundity and a shortening in their longevity. Moreover, the rate of predation was also reduced. When A. swirskii females were fed on nymphs of the twospotted spider mite Tetranychus urticae Koch after having been fed previously on protonymphs of either A. swirskii or A. exsertus increases in the rates of oviposition and consumption were observed, although these rates were lower than those of conspecific females reared continuously on the two-spotted spider mite only.

The effect of temperature on the biology, thermal requirement and life table of Agistemus exsertus Gonzalez and Phytoseius plumifer (Can. & Fanz.) feeding on immatures of Tetranychus urticae Koch, was determined at four temperature degrees, i.e. 20, 25, 30 and 358C. The total developmental durations of either predatory mite correlated negatively with increasing temperature. Minimum developmental thresholds (T o ) of egg, larva, protonymph, deutonymph stages and life cycle of A. exsertus females averaged 0.95, 9.25, 7.80, 1.03 and 5.29 respectively, while those of P. plumifer females were 6. 83, 9.35, 15.39, 15.40 and 13.22. On the other hand, A. exsertus and P. plumifer female required 416.66 and 126.58 DD, respectively, to reach adulthood. A. exsertus and P. plumifer net reproductive rate (R 0 ) averaged 16.13 and 8.23 then increased to 29.67 and 13.67 then sharply declined reaching 12.10 and 7.93 when the predator was kept at 20, 25 and 358C, respectively. r m values of A. exsertus reached 0.06, 0.11, 0.12 and 0.13 reared at 20, 25, 30 and 358C, respectively, while those of P. plumifer averaged 0.04, 0.11, 0.12 and 0.16. The doubling time (DT) of A. exsertus was 10.98, 6.10, 5.82 and 5.25, while that of P. plumifer averaged 15. 93, 6.18, 5.70 and 4.35 at 20, 25, 30 and 358C, respectively. Also, gross reproductive rate (GRR) of A. exsertus was 22.05, 51.70, 29.01 and 22.18, while that of P. plumifer averaged 12. 67, 18.20, 18.40 and 11.82 at the same temperatures. The finite rate of increase in e rm values of either predator increased positively with increasing temperature degree.

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Biological aspects and life table parameters of the predacious mites, Typhlodromips swirskii (Athias-Henriot) and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) consuming eggs of the Maskell scale insect, Insulaspis pallidula (Green) and the red date scale insect, Phoenicococcus marlatti Cockerell (Homoptera: Diaspididae, Phoenicococcidae) as well as pollen grains of date palm, Phoenyx dactylifera L. were determined under laboratory conditions. The life cycle and pre-oviposition period of T. swirskii were the shortest, while the oviposition period and female longevity were the longest as well as the egg production was the highest when fed on pollen compared with eggs of I. pallidula and P. marlatti. On the other hand, the life cycle, preoviposition and oviposition periods as well as the female longevity of E. scutalis were the best when devoured P. marlatti followed by pollen and I. pallidula. However, the total and daily fecundity of E. scutalis were the highest after consuming pollen compared with eggs of P. marlatti and I. pallidula. The sex ratio of females to total in the progeny of T. swirskii and E. scutalis was the highest when consumed I. pallidula followed by pollen and P. marlatti. Life table parameters were the most favourable for T. swirskii and E. scutalis feeding on date palm pollen compared with eggs of I. pallidula and P. marlatti.

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Predaceous insects and mites are important biological control agents of the two spotted spider mite Tetranychus urticae Koch. Biology and life table parameters of Stethorus gi/vifrons Mulsant, Phytoseiulus persimilis A.-H., Neoseiulus cucumeris (Oud.), Typhlodromips swirskii (A.-H.) and Euseius scuta/is A.-H. fed on T. urticae immatures was studied at 28 ±I 0 C. Their female life cycle and life span averaged 17.