EVALUATION OF RESISTANCE OF CUCUMBER CULTIVARS TO THE VEGETABLE LEAFMINER ( Liriomyza sativae Blanchard) (DIPTERA: AGROMYZIDAE) IN GREENHOUSE

The leafminer, Liriomyza sativae Blanchard, is distributed around the world and is an important pest of vegetables and ornamentals. Given the resistance potential of the leafminer to current insecticides, the use of resistant plant cultivars and parasitoids could be effective integrated pest management (IPM) strategies against it. Cucumber ( Cucumis sativus L.) is a preferred host for this insect. Seventeen cultivars of cucumber have been evaluated to study resistance mechanisms to L. sativae. All cucumber cultivars were evaluated in screening tests in greenhouse with indices such as the number of leafminer stings, the number of larval mines, the proportion of larval mines to leafminer stings, and the rate of injury. Significant differences (p < 0.01) were found among cultivars, as well as significant correlations among all evaluated indices. Cucumber cultivars were ranked by the cluster method based on all measured characters and were classified into four groups: susceptible, semi-susceptible, semi-resistant, and resistant. Trials of antibiosis resistance of cucumber cultivars were conducted in a growth chamber and were evaluated with biological indices of insect activity including oviposition period, larval and pupal duration, percentage of larval and pupal mortality, and the sex ratio among selected cultivars. Significant differences were found for all indices except pupal weight and the sex ratio. The cultivars were analyzed by the cluster method based on all measured characters and were divided into three groups including sensitive, slightly resistant, and semi-resistant. No cultivar was immune to injury

Toxicidad Fumigante de Algunos Aceites Esenciales sobre Adultos de algunas Plagas de Productos Almacenados.

Plant materials with insecticidal properties have been traditionally used for generations in some parts of the world. In this study, fumigant toxicity of some essential oils extracted from Rosmarinus officinalis L., Mentha pulegium L., Zataria multiflora, and Citrus sinensis (L.) Osbeck var. hamlin on adults of stored-product pests, including Tribolium castaneum, Sitophilus granarius, Callosobruchus maculatus, and Plodia interpunctella were investigated. Pure essential oils were used in glass vials for the bioassay. LC50 values of Citrus sinensis var. hamlin against T. castaneum , S. granarius , and C. maculatus were 391.28, 367.75, and 223.48 μL L-1 air after 24 h, 362.40, 20.45, and 207.17 μL L-1 air after 48 h, respectively. Furthermore, LC50 values of the fumigant test of C. sinensis and M. pulegium essential oils against S. granarius were 0.038 and 367.75 μL L-1 air after 24 h, 0.025 and 320.45 μL L-1 air after 48 h, respectively. On the other hand, LC50 values of R. officinalis and Z. multiflora on P. interpunctella moths were 0.93 and 1.75 μL L-1 after 24 h. Results showed that among tested essential oils, C. sinensis var. hamlin had good fumigant toxicity on T. castaneum , S. granarius , and C. maculatus . In addition, M. pulegium essential oil was stronger than C. sinensis var. hamlin on S. granarius . Results also indicated that both Z. multiflora and R. officinalis had fumigant toxicity on P. interpunctella adults. In summary, results indicated that these essential oils have good fumigant toxicity on stored-product pests.Materiales vegetales con propiedades insecticidas han sido usados tradicionalmente por generaciones en algunas partes del mundo. En este estudio se estudió la toxicidad fumigante de algunos aceites esenciales extraídos desde Rosmarinus officinalis L., Mentha pulegium L., Zataria multiflora y Citrus sinensis (L.) Osbeck var. hamlin sobre adultos de plagas de productos almacenados, incluyendo Tribolium castaneum, Sitophilus granarius, Callosobruchus maculatus y Plodia interpunctella. Para los bioensayos se usaron aceites esenciales puros en frascos de vidrio. Los valores de LC50 de C. sinensis var. hamlin contra T. castaneum , S. granarius y C. maculatus fueron 391.28, 367.75 y 223.48 después de 24 h y 362.40, 20.45 y 207.17 μL L-1 aire después de 48 h, respectivamente. Además, los valores de LC50 de la prueba fumigante del aceite esencial de C. sinensis y M. pulegium contra S. granarius después de 24 h fueron 0,038 y 367,75 μL L-1 aire y fueron 0,025 y 320,45 después de 48 h, respectivamente. Por otra parte, los valores de LC50 de R. officinalis y Z. multiflora en polillas de P. interpunctella después de 24 h fueron 0,93 y 1,75 μL L-1. Los resultados mostraron que entre los aceites esenciales, C. sinensis var. hamlin tuvo una buena toxicidad fumigante sobre T. castaneum , S. granarius , C. maculatus . Además, el aceite esencial de M. pulegium fue más fuerte que C. sinensis var. hamlin sobre S. granarius . Los resultados además indicaron que Z. multiflora and R. officinalis tuvieron toxicidad fumigante sobre adultos de P. interpunctella . En conclusión, los resultados indicaron que estos aceites esenciales tienen buena toxicidad fumigante sobre plagas de productos almacenados