February 2024 - 8

DR. BUGS | BY RAYMOND A. CLOYD
Stratiolaelaps
scimitus
Question: I want to try using
biological control agents against
fungus gnat larvae. I have heard about
a predatory mite. Can you provide
information on the predatory mite?
Answer: The predatory mite you are referring to is
Stratiolaelaps scimitus (formerly Hypoaspis miles),
which resides in the growing medium and feeds on the
larval stages of fungus gnats. This article will discuss
the biology, behavior, commercial availability and use of
Stratiolaelaps scimitus in greenhouse production systems.
BIOLOGY AND BEHAVIOR
Stratiolaelaps scimitus females are approximately
0.4 millimeters long and light brown, with a pale-brown
dorsal shield. Males are smaller than females. Females
lay up to three oval-shaped eggs per day in the growing
medium. The number of eggs laid by a female during her
lifetime depends on the nutritional quality of the prey
fed upon. Unfertilized females
produce only males, whereas
fertilized females produce males
and females. A population can
consist of 50% to 70% females.
Stratiolaelaps scimitus is shipped
in 1-liter containers (left) with
pasteurized peat (below)
or sawdust.
Adult Stratiolaelaps scimitus. Photos by Raymond Cloyd.
Nonfeeding larvae emerge (eclose) from eggs in one to
three days. The six-legged larvae become eight-legged
nymphal stages (protonymph and deutonymph). Eggs
and larvae are white. Nymphs are initially white, becoming
light brown as they age. Nymphs are present for four to
five days and become adults after six days.
The life cycle, from egg to adult, can be completed in 10
days at 82º F, 12 days at 75º F, 18 days at 68º F, and 34
days at 59º F. The optimum temperature for development
and reproduction is between 59º F and 86º F.
Stratiolaelaps scimitus resides in the upper 1 inch of the
growing medium. It is most active at temperatures up to
86º F with activity reduced when temperatures are lower
than 57º F.
Stratiolaelaps scimitus nymphs and adults feed on
fungus gnat, Bradysia spp., larvae. The nymphs and adults
can consume up to 30 larvae per day. After capturing
larvae, Stratiolaelaps scimitus insert their saw-like
mouthparts into the body, cut apart the internal tissues
and withdraw body fluids. In the absence of fungus gnat
larvae, Stratiolaelaps scimitus will feed on algae and plant
debris in the growing medium. Adults can survive three to
four weeks without a food source.
Paseurized
peat.
COMMERCIAL AVAILABILITY AND USE IN
GREENHOUSE PRODUCTION SYSTEMS
Stratiolaelaps scimitus is shipped in 1-liter
containers with pasteurized peat or
sawdust. Each 1-liter container
has approximately 25,000 mites
of all life stages (eggs, larvae,
nymphs and adults).
8 FEBRUARY 2024 GPNMAG.COM

http://www.GPNMAG.COM

February 2024

Table of Contents for the Digital Edition of February 2024

Editor's Report | Hot and cold
Table of Contents
Forty Under 40 Perspectives | Keeping fields cleaner
Dr. Bugs | Stratiolaelaps scimitus
Technically Speaking | LED lighting: A 2024 update
Plant Health | Healthy crops
Production | Understanding poinsettia heat delay
2024 California Spring Trials | CASTing into spring
Lighting | What's your lighting strategy
Pest Control | It's all about the buzz
Culture Report | DoubleShot series
Product Marketplace
Industry News/Events
Classifieds/Ad Index
February 2024 - Editor's Report | Hot and cold
February 2024 - 2
February 2024 - Table of Contents
February 2024 - 4
February 2024 - 5
February 2024 - Forty Under 40 Perspectives | Keeping fields cleaner
February 2024 - 7
February 2024 - Dr. Bugs | Stratiolaelaps scimitus
February 2024 - 9
February 2024 - 10
February 2024 - 11
February 2024 - Technically Speaking | LED lighting: A 2024 update
February 2024 - 13
February 2024 - Plant Health | Healthy crops
February 2024 - 15
February 2024 - 16
February 2024 - 17
February 2024 - Production | Understanding poinsettia heat delay
February 2024 - 19
February 2024 - 20
February 2024 - 21
February 2024 - 2024 California Spring Trials | CASTing into spring
February 2024 - 23
February 2024 - 24
February 2024 - 25
February 2024 - 26
February 2024 - 27
February 2024 - 28
February 2024 - 29
February 2024 - 30
February 2024 - 31
February 2024 - 32
February 2024 - 33
February 2024 - 34
February 2024 - 35
February 2024 - Lighting | What's your lighting strategy
February 2024 - 37
February 2024 - Pest Control | It's all about the buzz
February 2024 - 39
February 2024 - Culture Report | DoubleShot series
February 2024 - 41
February 2024 - 42
February 2024 - 43
February 2024 - Product Marketplace
February 2024 - 45
February 2024 - 46
February 2024 - 47
February 2024 - Industry News/Events
February 2024 - 49
February 2024 - Classifieds/Ad Index
February 2024 - 51
February 2024 - 52
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