ROLE OF CERTAIN BIOTIC AND ABIOTIC ENVIRONMENTAL FACTORS IN MANAGING MAJOR TOMATO INSECT PESTS

Abstract

Obtained data during autumn-winter plantation 2011-2012 on two tomato cultivars indicate that the cultivar Tomaland harbored a relatively high level of B. tabaci infestation as compared to the cultivar 888. During autumn-winter plantation 2012-2013, data clearly indicate that the population of B. tabaci during this season was much higher than that of 2011-2012. Statistical analysis of the data was carried out using the SAS statistical program, revealed that there were significant differences between the occurrence of eggs, nymphs and adults of B. tabaci inhabiting two different cultivars of tomato (888 and Tomaland) in the two winter seasons (2011-2012 and 2012-2013).The "F" value for each stage and for the total population was highly significant for the tested cultivars, between seasons and dates of sampling. The interaction between these three variables was also highly significant revealing the great variation in the distribution of B. tabaci along the winter season and sampling dates in the tested two tomato cultivars.

Spring-summer plantations Data of spring-summer plantation 2012 clearly indicate that the cultivar Hybrid Super, harbored high levels of B. tabaci infestation as compared to the cultivar Crystal. The same trend was observed during spring-summer plantation 2013. These results indicate that the Hybrid Superis more susceptible to whitefly infestation than the cultivar Crystal. On the other hand, data revealed the population density of B. tabaci was higher on spring-summer plantation 2013 as compared to spring-summer plantation 2012. Careful examination of the data and the results of statistical analyses which confirm the presence of highly significant differences between different developmental stages of B. tabaci inhabiting tomato plants regardless of planting dates. These results show that the population density of egg stage was very high as compared to the produced population of nymphs. These results could be explained as that tomato plants are not preferred host plant for B. tabaci nymph's feeding.The same results clearly show that the population size of B. tabaci adults inhabiting tomato fields is much larger than that of nymphs confirming occurrence of B. tabacimigrating from adjacent or surrounding plants to tomato fields which leads to that increase in adult's population.

Aphids and potato leafhopper, Empoascadecipiens Paoli Autumn-winter plantations Data of the fluctuations in the population densities of aphids and E. decipiens during autumn-winterplantatuins of 2011-2012 and 2012-2013 reveal that the tomato cultivar Tomaland harbored relatively high level of population density of aphids and leafhoppers as compared to the cultivar 888.In addition, the population density of the two insect pests in general were relatively higher in 2012-2013 as compared to 2011-2012. According to the statistical analysis, there were significant differences in the occurrence of aphids throughout the two investigated seasons and the period of sampling. On the other hand, the tested tomato cultivars did not differ from each other in aphid infestation. The "F" values for seasons and dates of sampling were highly significant and for the tested cultivars, it was not significant. The interaction between these two significant variables was also highly significant revealing the great variation in the distribution of aphids along the winter season and sampling dates regardless of the two tomato cultivar.For E. decipiens, almost the same trend was observed since "F" values for seasons and date of sampling were highly significant and for the tested cultivars, it was also non-significant.