Experiments were carried out at tomato field at Qalyubyia Governorate, Egypt cultivated with two different cultivars to test its susceptibility to infestation with Bemisia tabaci (Gennadius); aphids {Aphis gossypii and Myzus persicae (Sülzer)}; Empoasca decipiens Paoli and Tuta absoluta (Meyrick) in addition to the seasonal abundance of these pests on the two cultivars in two successive summer seasons (2012 and 2013). Results indicated that B. tabaci and aphids had two peaks of abundance in May and June in both years on both cultivars. E. decipiens also had two peaks of abundance in May and June in both years with no significant difference between the two cultivars. The two tested cultivars almost harbored the same population density of the immature stages of T. absoluta during summer season, 2012. The pest had only one peak during the last week of May. There was negative and highly significant correlations between the population densities of all considered pests and the numbers of hairs (trichomes) present on tomato leaves sampled on 20 May and 4 June except for aphids which disappeared during hot summer months on the cultivar Hybrid Super. In the third sampling date (20 June, 2013), the correlation was also negative and highly significant with the population of B. tabaci and positive with the population of T. absoluta. The same trend was observed on the cultivar Crystal HYB. The effects of (N), (P) and (Ca) were positive and highly significant on all considered pests on both cultivars. The effect of (K) was negative and highly significant on all considered pests on both cultivars. The effect of (Mg) was positive and highly significant on the cultivar Hybrid; while it was negatively correlated with sap sucking pests only on the cultivar Crystal. Data indicate that the effect of Fe, Zn and Mn was positive and highly significant on both cultivars and Cu was negatively affected these pests on both cultivars.
Certain ecological aspects of the Seychellarum mealybug, Icerya seychellarum (Westwood) which is considered as a key pest on coffee trees, a promising newly crop cultivated in Egypt, have been investigated under two different ecosystems throughout two years, 2009 & 2011. Results revealed that this mealybug species was found all the year round in both localities. The total population recorded four peaks of seasonal abundance in both investigated ecosystems on coffee trees and it passed through three overlapping generations in both ecosystems. The main weather factors, four weeks earlier, showed miscellaneous effects on the population dynamics of this mealybug species. Means of minimum and maximum temperature had a positive significant effect; while mean percentage of relative humidity showed insignificant effect in the two localities. The combined effects of the four weather factors, as a group, had significant effects on I. seychellarum population throughout both years. In Qalyubyia Governorate (2009), the percentage of explained variance was 56.8%; while in Giza Governorate (2011), this value was 65.9%.
The effects of four sowing dates (early of April, May, June and July) and three major climatic factors (means of maximum & minimum temperatures and percentage of relative humidity) on the seasonal abundance of three stem borers (Sesamia cretica Led., Chilo agamemnon (Bles.), Ostrinia nubilalis Hbn represented by larval content and Rhopalosiphum maidis Fitch represented by total numbers of nymphs and adults) throughout two successive growing seasons 2014 and 2015 were investigated. The highest numbers of S. cretica larvae were found within April plantation with a peak on the 3 rd week of May during both seasons; while maize plants sown on June and July were almost free of infestation. Maize plants sown on June and July were more liable to be attacked by C. agamemnon as compared to April and May sowing dates. Maize plants sown in April and May in both seasons were almost free from the infestation with O. nubilalis larvae. The highest numbers of R. maidis population was occurred for maize sown on July followed by those sown on June in both seasons. For June plantation, two peaks of abundance occurred on the last week of July and the 1 st week of September, whereas only one peak was occurred on July plantation during the 1 st week of September. The lowest numbers occurred on maize plants sown on May, while plants sown on April were free from aphid infestation. We concluded that sowing maize plants during May and June escapes from severe infestation with stem borers and aphids, however April plantation is almost free from infestation but its yield is very low. The effect of mean maximum and minimum temperatures during May plantation was significant negative on the changes in the population of S. cretica. Mean maximum temperature had a negative effect; while mean minimum temperature had a positive significant effect on the population dynamics of C. agamemnon during May plantation. The mean maximum temperature during May and June plantations on O. nubilalis larvae was significant; while the effect of mean minimum temperature was insignificant during both seasons of study. Means of minimum temperature during May and June plantations were positively significant on the changes of R. maidis population and the same trend was observed for R.H.%. It could be concluded that mean maximum and minimum temperatures are affecting the infestation with stem borers and mean minimum temperature and R.H% are the most factors affecting R. maidis population.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.