Competition between Frankliniella occidentalis and Thrips tabaci on cucumber and their abundance on several greenhouse plants

The abundance of the western flower thrips, Frankliniella occidentalis, along with the onion thrips, Thrips tabaci, in the greenhouse of tomato, cucumber, Alstroemeria, Rose and Gerbera were determined by weekly sampling from November 2018 to May 2019 in Isfahan districts. The competition ability of these two species on cucumber was evaluated by comparing their fertility-life table parameters at two different temperatures and also by measuring the density of each species over time with different initial densities of both species. The results showed that the population of the western flower thrips was always higher than onion thrips in greenhouses. The fertility- life table parameters showed that an increase in temperature leads to increase the western flower thrips’s population. At 25 ° C, the intrinsic rate of increase (0.17 day-1) and the net reproductive rate (51 nymphs) of onion thrips were higher than the western flower thrips, and at 27 ° C the western flower thrips had higher intrinsic rate of increase (0.18 day-1) and net reproductive rate (45 nymphs) than those of onion thrips. Since the value of intra-specific competition for onion thrips (0.34) and western flower thrips were 0.34 and 0.14, respectively. The onion thrips population growth is more affected by intraspecies competition than western flower thrips and so the western flower thrips is more successful in interspecific competition than onion thrips.