Thrips tabaci
Life History and Reproduction
Life History:
Onion thrips spend the winter in sheltered areas of plants, such as
remnants of onion plants left in the field or crowns of alfafa and clover (Center
for Integrated Pest Management 2012).
In the spring, development resumes and winged adults search for suitable
host plants. They are incredibly small organisms, so they cannot be
identified with a hand lens. High microscope magnification is necessary for
identification. Characteristics that enhance their pest status include
a short generation time, high reproductive potential, asexual reproducti
on
by females, and the occurrence of protected, non-feeding life stages (Utah
State University Extenstion 2008). For
more information on
the life cycle,
click here.
Stages in the development cycle:
Egg, first larval stage, second larval stage, prepupa,
pupa, and adult. The only damaging stages are the
two larval stages and the
adult stage. The complete
life cycle, from an egg to the adult stage, takes 14-30
days. When temperatures are over 30°C, their life
cycle can be shortened to 10 or 11 days. The adults
may live up
to 20 days (Utah State University Extension 2008).
Reproduction:
Reproduction is through a process called parthenogenesis, in which females
do not need a mate, which leads to ratios of 1 male to 1,000 females.
This is also called asexual reproduction. Females that do not mate
will only produce female progeny. Males are wingless and extremely
rare. A female Onion thrips produces 10 to 100 eggs which she inserts
individually into tender plant tissue of the epidermis. Eggs are
elliptical and are microscopic. These eggs take 4 to 10 days to hatch.
The larvae feed for 5 days, then they pupate in the soil. The prepupa
and the pupa are the two non-feeding stages. Approximately 4 days
later, new adults emerge from the soil to feed and lay eggs.
Winged adults are weak fliers, but they are able to fly from plant to plant
and may even be carried by wind for long distances. Females live for two to
three weeks and each are able to lay about 80 eggs (Utah
State University Extension 2008).
