Thrips tabaci
Nutrition: Food Sources and Techniques Used
Thrips tabaci are the most damaging insect pest of onions known today. They have a very peculiar feeding behavior. Onion thrips prefer to feed on the young plant tissue on the newest emerged leaves. Under crowded conditions, they will migrate to leaf tips to feed. Adult and larval thrips feed in the mesophyll layer, using a punch-and-suck behavior (Utah State University Extension 2008).
Their mouthparts are shaped like beaks with one large mandible, or tooth.
They start the feeding by piercing and rasping the leaf surface with their
mouth parts. Sap is released from the injured plant, and is sucked up
with their mouth along with other plant content. They suck out the
contents by pressing their mouthparts onto the damaged surface.
During this process, they release substances that help predigest the onion
plant tissue. The removal of chlorophyll causes the feeding area to
appear white to silvery in color, and these areas may resemble patches or
streaks. Tiny black spots are a sign that leaves have been fed on heavily.
Moderate to severe feeding causes reduced bulb size in plants (Lewis
1997).
Hosts: Onions, garlic, and other related plants are the
preferred hosts. Other cultivated crops or plants also serve as a
host.
Thrips tabaci feed on many cultivated crops as well as
uncultivated plants in at least 25 families. They feed on young leaves
on the inside of the onion neck while the plant is underground. They may
feed on bulbs when the plant is in storage. Although they primarily
feed on onions, this is not always the case. Principle crop hosts
include beans, broccoli, carnations, cotton, garlic, turnip, tomato, squash,
tobacco, pineapple, peas, head cabbage, rose, papaya, orchids, leek,
cucumber, melon, cauliflower, carrots, and Chinese broccoli (Center
for Integrated Pest Management 2012).
They have an open circulatory system.
It stores its food in an internal chamber, using substances to help with the
breakdown of the plant tissue (Encyclopedia of
Life 2011).
Onion thrips can vector plant viruses and diseases, especially the fungus, purple blotch. The viruses use this organism to survive and for transport (Utah State University Extension 2008).
Let's move on to the Life Cycle and Reproduction characteristics...