Paper presented at the 52nd CFCS Annual Meeting, Guadeloupe, July 10-16, 2016 Carbon dioxide plays a major influence (at least 73%) on warming the greenhouse gases followed by methane, nitrous oxide and other gases. Atmospheric CO2 concentrations have been increasing at an astonishing rate because of human activities, such as rapid exploration fossil fuels and deforestation. Global CO2 concentrations in the atmosphere increased from 270 ppm in preindustrial age to the present 381 ppm. This is a 41% increase during the last 150 years. Hence, most of the current research studies on insects address the effects of carbon dioxide on their life history parameters. Thrips can be considered an example of a good group of insects to study for climate change. They are very small (ca. 1 mm) and efficient in adapting to their environment. Melon thrips (Thrips palmi Karny) and common blossom thrips (Frankliniella schultzei Trybom), are two species of this group. Our present study will focus on various biological aspects of these two thrips. Melon thrips which is an economically important invasive pest of all vegetable crops grown in the southern Florida. Although native to Sumatra, this thrips is widely distributed, and has dispersed to many countries in Asia, Africa, Central America, Oceania, and Europe.
Fig. 2. Defoliation of `Pod Squad’ bean by Thrips palmi, 1992
Melon thrips has a short generation time consisting of 13-18 days which is the total of egg, larva, pre-pupa, pupa, and adult stages. Adult life span lasts for 10 – 30 days depending on temperature. During the life time, a female lays up to 200 eggs. Because of the short generation time, high reproductive rate, and polyphagous habits, this thrips is an excellent candidate for studying its biology in relation to various abiotic factors, such as, temperature, rainfall, solar radiation, and greenhouse gases, specifically CO2. Since its invasion of Florida in 1990, we have been studying melon thrips seasonal abundance on various vegetable crops, and their within field distributions and management programs to document the effects of climate change on its biology and behavior. In southern Florida, melon thrips arrives in the vegetable fields at the beginning of growing season in September–October, when their density is typically 2-5 thrips/bean leaf, they reach peak density during February–April with 100 -300 thrips/bean leaf. Abundance of melon thrips decreases significantly after May because of reduced vegetable production and increasing rainfall. Melon thrips population showed decreasing trend as year progressed from 1990 to onward because of improved management programs (insecticides), and biotic (predators) and abiotic environmental factors (rainfall, temperature). Melon thrips abundance became very low (1-4/10 bean leaves) in 2006 because of using spinosad (SpinTor, Dow AgroSciences) and other effective insecticides. However, melon thrips populations began increasing after 2006 because of sole reliance on few insecticides; they are presently considered an economic pests of all vegetable crops.
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