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Dimilin, effective against Lernaea (anchor worm)
Dimilin is used mainly to control insects on crops and is not
licensed for fish use. The concern is it's indiscriminant action
against aquatic insect life. Such concerns are justified when used in
natural environments such as lakes and rivers - but clearly less of a
concern in garden ponds
This is an effective treatment against copepod crustacean parasites
such as Lernaea (Anchor Worm), Ergasilus (gill maggots),
and is less toxic towards fish than organophosphates.
Having searched available literature, there are mixed opinions as to
the effectiveness of dimilin against branchiuran parasites such as Argulus
sp. (fish lice). Theoretically it should be effective against the
larval stages, as these have to go through several molts. I suspect the
difference of opinion arises over the effect on adults.
How does it work?
Insects have an exoskeleton - which basically means they have their
skeleton on the outside, rather than the inside as we do. There
are differences in the structure of their skeleton and unlike ours, it
doesn't grow with them.
To overcome this problem, insects go through growth cycles, during
which they shed their old, smaller exoskeleton and make their bodies
swell by taking air into the respiratory system (which is spread through
out their body, but that's a different story). As their body expands it
stretches the new, elastic cuticle before it sets hard. They may repeat
this process several times before reaching adulthood.>
The main component of the insect exoskeleton is a substance called
chitin. Diflubenzuron (dimilin) works by interfering with the
development of the new chitin exoskeleton, so the insect larvae
continues to feed and develop normally until they shed their old
exoskeleton. They die because the new exoskeleton is not properly
formed.
Dosage rates:
The recommended dosage rate is 0.03mg / litre (=0.11 mg / US gallon /
0.14 mg . Imp gallon). 76% of the treatment persists after one
week. A second treatment 10 -14 days later should remove all stages of
the parasite.
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Useful conversions
are:
ppm =
mg/litre
i.e. 5 ppm = 5 mg / litre
mg / litre x
3.785 = mg / gall
(US)
i.e 5 mg / litre = 18.9 mg / gall (US)
mg/ litre x 4.546 =
mg / gall
(UK)
i.e 5 mg / litre = 22.7 mg / gall (UK)
To convert imperial
gallons to US gallons multiply by 1.2
Other useful
figures:
1 ounce = 28.35 grams
1% solution =
10 ml per litre
10 gram per litre
38 gram per
gall (US)
45 gram per gall
(UK)
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