Insect Pest Incidences and Yields of Tomatoes Grown in High Tunnel and in Open Field in Mwea Division, Kirinyaga County, Kenya
Mueke, Pauline Mbinya
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Tomato, Lycopersicon esculentum, is a major horticultural crop grown in many areas in Kenya. The main constraint to tomato production is insect pests with farmers relying heavily on chemical pesticides to control them. This has led to several problems such as contamination of farm produce and pollution of the environment among others. There is need therefore need for alternative methods to control insect pests. A study was carried out in Mwea region of Kirinyaga County to assess the insect pests incidences and the yields of tomatoes grown in open field and in high tunnel. Three tomato varieties, grafted Onyx, non-grafted Onyx and Anna F1 were planted in the two production systems in a Complete Randomized Block Design. Data collection commenced two weeks after transplanting. Assessing the abundance of insect pests on tomatoes was carried out by counting the numbers of insect pests and mines on tomato leaves. Ripe tomatoes were harvested per variety, sorted and classified into marketable and unmarketable fruits. The total fruit weights and marketable fruit weights were obtained. The data on the abundance of different insect pests and the yields of the three tomato varieties was subjected to Analysis of Variance (ANOVA), while abundance of insect pests and fruit yield for the two production systems was analyzed using a paired sample t-test. The significance level was set at P= 0.05. The means were separated using the Student-Newman-Keuls (SNK). The insect pests species recorded attacking tomatoes were Bemisia tabaci, Frankliniella occidentalis, Aphis gossypii and Liriomyza trifolii. In cropping season one, the mean numbers of F. occidentalis, B. tabaci, A. gossypii and the mean numbers of L. trifolii mines were significantly higher on tomatoes in open field compared with those in high tunnel. In cropping season two, the mean numbers of B. tabaci were significantly higher on the tomatoes grown in open field compared with those in high tunnel (P=0.0001). However, there were no significant differences between the mean numbers of L. trifolii mines recorded on the tomato plants grown in high tunnel and in open field (P=0.107). The mean total and marketable fruit weights were significantly higher for tomatoes harvested in the high tunnel compared with those harvested in open field in cropping season one (P=0.0001). The mean marketable fruit weights were significantly higher for tomatoes harvested in the high tunnel compared with those harvested in open field in cropping season two (P=0.0001). There was lower incidence of insect pests on tomatoes in the high tunnel and this probably could have contributed to higher total and marketable fruit weights of tomatoes harvested in the high tunnel. There is therefore need to encourage tomato farmers in the country to embrace high tunnel technology in tomato production.
- MST-Zoological Sciences