About Tobacco ThripsReproduction and Life Cycle Tobacco thrips will go through 3 to 5 generations annually, depending on climate conditions. One generation will generally take about 20 days to complete. They overwinter as adults in the ground among plant debris. They will emerge in the spring and find available host plants such as tobacco, grass, weeds, or small grains. They place their eggs on the foliage within the plants tissue, usually laying about 50 eggs in these clusters. The eggs take a week to hatch. The hatched larvae go through 2 instars, which last about 4 to 12 days. The larvae typically congregate on blooming flowers and fresh fruit. When they pupate, they will remain in this stage for anywhere between 3 to 13 days. An adult’s lifespan can last up to a month. Tobacco Thrips Identification and HabitatIdentification The adults are very small, typically 1 to 2mm long. They are yellow-brown and have thin bodies. 1 of the 2 types of tobacco thrips has shorter wings than the other, but both wing pairs are mainly made of fringe hairs. Their mouthparts can cut into the plant, allowing the thrip to feed on the plants sap. The eggs are extremely small, white and are hidden in plant tissue. The larvae have a body shape comparable to that of the adult; however, they do not possess fully developed wings. They are lighter in colour to that of the adult, usually off-white to tan and about 0.25 to 1mm long. The pupae are approximately 0.6 to 1mm long and are usually a yellowish colour with white wing pads. Habitat The adult tobacco thrips like to eat the pollen and tissue from flowers; this is mainly because the pollen can help speed up their reproduction rate. They will often reproduce in peanut plants, which is when they obtain tomato spotted wilt virus. This can become a major problem when this pest migrates to other plants that are susceptible to this virus such as peppers and tomatoes, and transmit it. This virus gives leaves a spotted appearance, it will begin to wilt, and the plant is often smaller in size to other plants that have been unaffected. If the disease was transmitted early in the plants development, it will not provide any fruit. If the plant was infected later on, the fruit will portray strange ripening symptoms and will usually be unmarketable. However, they can also be especially damaging to peanuts if the plant is still in the early stages of development. They can damage the leaflets, leaving them with a deformed and scarred appearance and can sometimes stunt the plant. Tobacco Thrips Management and Control MethodsCultural Control A substantial rainfall can significantly reduce the tobacco thrips population. It is worth mentioning that the damage this pest causes is often hard to notice until a few weeks after the infestation had begun. If you put ultraviolet-reflective mulch with your plants that are at risk, this can reduce the number of adults that choose these plants as hosts, which will help keep the tomato spotted wilt virus from spreading. Additionally, there are cultivars that are resistant to this virus for tomatoes and peppers. The nematode Thripinema fuscum has also proven to be effective at controlling this pest. Chemical Control The insecticide spinetoram has proven to help reduce thrips as a post-emergence tactic. However, be aware that insecticides cannot help with the spread of tomato spotted wilt virus; once a plant is infected there is no treating it, often making insecticides economically unjustifiable. If you do decide to use a pesticide, be sure to carefully read the label for cautions and proper application. It is extremely important to never spray on days that are windy. After applying insecticides, it is important to irrigate sprayed area to increase the insect control. That being said a large rainfall or irrigation soon after the application can reduce the concentration insecticides. Latin / Alternative Tobacco Thrips NamesSources http://tobacco.ces.ncsu.edu/tobacco-pest-management-insects-tobacco-thrips/ http://ipm.ncsu.edu/AG271/peanuts/tobacco_thrips.html http://www.ent.uga.edu/veg/solanaceous/thrips.pdf http://ipm.ifas.ufl.edu/pdfs/Tobacco_thrips.pdf |