Restricted infection of a lower leaf of cucumber, Cucumis sativus L., with the anthracnose fungus Colletotrichum lagenarium has been previously shown by others to induce persistent, systemic resistance to the same fungus and to at least 12 other diverse plant pathogens. The non‐specificity of pathogen‐induced resistance has fueled speculation that it might also affect arthropod herbivores. However, we found that immunization of cucumber with C. lagenarium had no effect on population growth of twospotted spider mites, Tetranychus urticae Koch, reared on foliage for which induced resistance to the same pathogen was confirmed. Similarly, immunization with C. lagenarium had no systemic effect on weight gain, duration of development, or pupal weight of fall armyworms, or on progeny production by melon aphids. In reciprocal tests, previous feeding injury from spider mites or fall armyworms did not induce systemic resistance to C. lagenarium. These results indicate that, at least for cucumber, pathogen‐activated induced resistance is specific to plant pathogens, suggesting separate mechanisms of induced resistance to pathogens or herbivores. Résumé Est‐ce que l'immunization du concombre contre l'anthracnose par Colletotrichum lagenarium affecte ses propriétés d'hôte vis‐à‐vis des arthropodes? Dans une étude de résistance induite, l'infection basale des feuilles du concombre, Cucumis sativus L., avec Colletotrichum lagenarium, le champignon de l'anthracnose, a généré une induction systémique et persistante, non seulement au même champignon, mais aussi et surtout à l'égard de douze autres. La nature non‐spécifique de cette résistance a dès lors engendré une hypothèse, celle de savoir si cette non‐spécificité pourrait s'entendre au niveau d'arthropodes phytophages. Cependant, nos travaux ont démontré que l'immunité vis‐à‐vis de C. lagenarium n'affecte ni la population de tétraniques, Tetranychus urticae Koch, élevée sur des feuilles résistantes de concombre; ni le gain pondéral, ni la durée de développement, ni le poids nymphal de Spodoptera frugiperda, ou la fertilité des aphides de melon. De ces résultats, il peut‐être déduit que, au moins chez le concombre, l'induction de résistance due à C. lagenarium démeure spécifique aux champignons saprophytes, c'est à dire qu'il existe des mécanismes séparés pour la résistance, soit aux champignons, soit aux arthropodes phytophages.

This work is the first study to investigate the efficacy of the commercial formulation of Beauveria bassiana (Broadband) to control adults of red palm weevil (Rhynchophorus ferrugineus (Olivier)). This fungus could be applied as one of the biological tactics in controlling red palm weevil. Bioassay experiments for medium lethal concentrate and medium time to cause death of 50% of red palm weevil adults were carried out. The result showed that the LC50 of B. bassiana (Broadband) was 2.19×10(7) and 2.76×10(6) spores/ml at 9 and 23 d of treatment, respectively. The LT50 was 13.95 and 4.15 d for concentration of 1×10(7) and 1×10(8) spores/ml, respectively, whereas 1×10(9) spores/ml caused 100% mortality after 24 h. Additionally, a red palm weevil pheromone trap was designed to attract the adults to be contaminated with spores of Broadband, which was applied to the sackcloth fabric that coated the internal surfaces of the bucket trap. The mating behavior was studied to determine direct and indirect infection of the spores from male to female and vice versa. The results showed a high efficacy of Broadband suspension at 1×10(9) spores/ml; 40 ml of suspension at this concentration treated to cloth in a trap caused death of contaminated adults with B. bassiana spores directly and indirectly. The 100% mortality was obtained even after 13 d of traps treatment with 40 ml of the suspension at 1×10(9) spores/ml.

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Four piercing-sucking insects whiteflies, Bemisia spp., thrips, Thrips spp., leafhopper, Emposca spp. and aphids, Myzus persica & Aphis gossypii, were monitored on cucurbit plants (cucumber, squash, melon and watermelon) during May and June, 1999. Sticky traps were placed at the plant height in fields of three districts, Al-Hasa, Qatif and Riyadh. Data showed that the mean number of whiteflies/trap was higher in Al-Hasa district when compared with that of Qatif and / or Riyadh. Moreover, whiteflies population was abundant in May than that in June at Al-Hasa and Qatif fields, while very small number of adults was captured on traps in May at Riyadh. Same trend of thrips number was observed, whereas Al-Hasa district had the highest number in both inspection months. In the meantime, thrips population was more in May compared with that of June. The mean number of leafhopper /trap was higher in Riyadh followed by Al-Hasa and Qatif and the prevalence of leafhopper population was more in May compared with that in June. However, the mean number of aphids/trap was higher in Riyadh followed by Qatif and Al-Hasa. The frequency of insects in descending order was as follows: whiteflies, thrips, leafhopper and aphids.

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