Ectoparasitic arthropods are a diverse element of the Saudi fauna. Due to this, a survey of ectoparasites associated with rodents was conducted as a preliminary study in five districts of Hail region of northern Saudi Arabia for the first time. Ectoparasites extracted from 750 rodents were sampled and identified by recording their frequency of appearance. Results revealed that 1,287 ectoparasites infested 316 of the captured rodent hosts. These ectoparasites parasitized on four species of rodents including three species of rats Rattus rattus rattus, Rattus rattus frugivorus, and Rattus rattus alexandrinus and one species of mouse Acomys dimidiatus (Rodentia: Muridae). The ectoparasites belong to four different groups: ticks, fleas, lice, and mites. Ticks were the highest in the number, while fleas were the lowest among all the extracted ectoparasite groups. The collected ectoparasitic arthropods consisted of seven species. Ticks were of two species: Rhipicephalus turanicus and Rhipicephalus sanguineus (Acari: Ixodidae), fleas were of two species: Xenopsylla cheopis and Xenopsyllus conformis mycerini (Siphonaptera: Pulicidae), lice was a single species: Polyplax serrata (Anoplura: Hoplopleuridae), and mites were of two species: Laelaps nuttali and Laelaps echidninus (Mesostigmata: Laelapidae). The findings of the study showed that the intensity of infestation was varied between rodent host sexes, wherein females had the highest rate of parasitic infestation, and the parasitic index of appearance was very high for one group of parasites (i.e., ticks). The parasitic prevalence was 42.13 % on rodents, and mites were the most prevalent parasite species. Overall, this study was carried out to establish baseline data for ectoparasite-infested rodents in Hail region, Saudi Arabia, and may help for appropriate planning to control zoonotic diseases in this area.

Laboratory experiments were performed to evaluate the pathogenic and lethal effects of the entomopathogenic nematodes Hb (Heterorhabditis bacteriophora Poinar) and Sc (Steinernema carpocapsae All strains) on the full grown larvae, newly formed pupae and seven days old adults of the peach fruit fly, Bactrocera zonata and the cucurbit fly, Dacus ciliatus. Mortality rates ranged from 9.3 to 42.7%, 12.7 to 52.3 % for the full grown larvae of both B. zonata and D. ciliatus treated by Sc nematode, respectively, and from 67.3 to 100%, from 46.3 to 100% for the full grown larvae of both B. zonata and D. ciliatus treated by Hb nematode, respectively, whereas mortality rates of pupae ranged from 2.7 to 32.7% for the pupae of B. zonata treated by Sc nematode, from 1.7 to 23.3% for the pupae of D. ciliatus treated by Sc nematode , from 12.7 to 51.7 % for the pupae of B. zonata treated by Hb nematode and from 6.3 to 39.3 % for the pupae of B. zonata treated by Hb nematode. Furthermore, the mortality rates varied from 35.0 to 78.7% , 7.7 to 50.3% for 7 days old adults of both B. zonata and D. ciliatus treated by Sc nematode, respectively, 41.7 to 90.3 and 17.0 to 67.7 % for 7 days old adults both B. zonata and D. ciliatus treated by Hb nematode, respectively. LC 50 and LC 90 values were 325.3, 286.2, 1718.6 and 1650.0 IJs/ cm 2 for larvae of B. zonata and D. ciliatus treated with Sc nematode, 28.8, 56.7, 167.2 and 156.1 IJs/cm 2 for larvae of B. zonata and D. ciliatus treated with Hb nematode, 540.2, 447.4, 1785.4 and 2009.8 IJs/ cm 2 for pupae of B. zonata and D. ciliatus treated with Sc nematode, 235.0, 420.8, 1167.0 and 1941.5 IJs/ cm 2 for pupae of B. zonata and D. ciliatus treated with Hb nematode, 116.8, 261.6, 319.3 and 375.0 IJs/ cm 2 for adults of B. zonata and D. ciliatus treated with Sc nematode and 77.3, 196.7, 290.8 and 253.7 IJs/ cm 2 for adults of B. zonata and D. ciliatus treated with Hb nematode, respectively. From the obtained results we can conclude that the entomopathogenic nematodes: Hb Heterorhabditis bacteriophora Poinar) and Sc (Steinernema carpocapsae All strains) were effective on the different stages of B. zonata and D. ciliatus , Hb nematode was more virulent than Sc nematode and the larvae and adults of B. zonata and D. ciliatus were more susceptible to the nematodes infection than the pupae.

Three bio insecticides Biolarve and Triamph derivate from emamectin benzoate and W-Bus which derivate from Bacillus thuringiensis (Bt), in addition to one organophosphorus insecticides Linker tested for their effects on 2 nd and 4 th larval instars and egg masses (24, 48 and 72 h old) of the Egyptian cotton Leafworm Spodoptera littoralis (Boised) infested tomato crop under field and semi field conditions. The doses used were the recommended dose by Egyptian agricultural ministry. The obtained results showed that all insecticides were potent and effective in controlling S. littoralis caused highly mortality and reduced the number of all tested larval instars and egg masses. The bio pesticides caused lower mortalities percentage than the chemical one in case of initial kill calculations, but after one day till ten days caused higher mortalities percentage than the organophosphorus insecticides. The second larval instar recorded sensitive reaction than the fourth larval instar of S. littoralis, which shown more resistant to all examined insecticides.

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The biological and biochemical effects chloropyrifos, camphor extract and their combination were studied against the 4 th instars of Spodoptera littoralis under semi-field conditions. The results indicated that the LC 50 for chloropyrifos was 0.08 ppm and 13.3 x 10 3 ppm for the camphor extract. The estimated Co-toxicity factor was 13.2 So, there is an additive effect between camphor oil and chloropyrifos against S. littoralis.Oil extract of camphor prolonged larval and pupal duration also the same effect happened when using mixture of camphor extract and chloropyrifos. This prolongation was accompanied with a reduction in pupal weight of the treated larvae. While when using chloropyrifos only the larval and pupal duration were shortened Also % of pupation and % of adult emergence were more decrease in plant extract and insecticide mixture than each compound alone.Biochemical studies showed that, total protein content of larval instars decreased by 31, 26 and 13.5 % for camphor extract, chloropyrifos and its combination, respectively. Also, the activity of acid phosphatase, α-esterase was significantly decreased. Where the alkaline phosphatase, activity increased When compared with control.