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Othiorhynchus
sulcatus |
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Adult weevils feed at night producing telltale notches around the edges
of leaves and flowers. The damage is most severe when caused by the
voracious larvae, feeding on roots. Heterorhabditis-System provides rapid
and effective control of vene weevil.
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Biology - Black vine weevil
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Adult vine weevils are 8-12 mm long, have a grooved, dull black
shell with patches of tiny yellow bristles. As they are well
camouflaged and only active at night, they are seldom seen. If they
are discovered, they play dead very convincingly.
Outdoors, adult vine weevils emerge from the soil from May
onwards. They are wingless, but walk and climb exceedingly well.
Male weevils do not occur here. The freshly emerged females feed for
about ten days, then commence laying the unfertilized eggs close to
well-selected plants. Each female lays about 500 eggs, which are
very small (0.8 mm diameter) and round. Initially, these eggs are
white, but they turn brown as they mature. As adults are relatively
long-lived, egg-laying can extend well until October.
Eggs hatch in 8-20 days, and the tiny emerging larvae burrow deep
down into the compost. The larvae are C-shaped and legless. They
have a creamy white colour with a shiny brown head. When fully
grown, they are 10-14 mm long.
Vine weevils overwinter as larvae, which pupate in spring as
temperatures rise. These pupae are cream-coloured and soft bodied.
They are found in cavities several centimetres down in the soil.
Adult weevils emerge some 3-4 weeks later. In heated glasshouses,
the life-cycle is completed more rapidly and several different
stages of vine weevil may be found at any time of the year. |
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Damage |
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Adult weevils feed at night producing telltale notches around the edges
of leaves and flowers. This is often the first sign of vine weevil
activity. The damage is most severe when caused by the voracious larvae of
the vine weevil. Emerged from the eggs, they feed on little roots. As they
grow, they gradually attack bigger roots, tubers, rootstocks and even
strip bark from woody stems. As a result, the damaged plant wilts and dies
off.
Sometimes, it takes a long time before damage is determined. At that
moment, the plant is often already severely weakened and beginning to die
off. Slow growing plants, which are unable to compensate for loss of root
tissue are most subject to damage.
Crops frequently attacked include:
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Beneficials |
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Heterorhabditis
megidis |
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| Heterorhabditis-System is based on a unique strain
of the insect parasitic nematode Heterorhabditis megidis,
which seeks out and destroys vine weevil larvae in compost. |
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Responsibility and
copyright | |
