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Aphidius colemani/ervi mix – 750 pcs

Parasitic Wasps of Aphids

Aphidius colemani and Aphidius ervi are both parasitic wasps of a wide range aphid species. Using a mix of the two has a far greater probability of success in a greenhouse situation. Ervi are twice the size of colemani. Allowing them to parasitize larger aphids. Colemani have a faster reproduction rate which allows them to have a faster effect on aphid populations. If using parasitic wasps for the first time it can be a good idea to have make initial purchase of the mix and see which species has the greater effect on your aphid ifestation.

Aphidius colemani/ervi mix – 750 pcs

$136.50

Parasitic Wasps of Aphids

SKU: ACOL-ERV-MIX.

Aphidius colemani/ervi mix – 750 pcs

$136.50

Parasitic Wasps of Aphids

SKU: ACOL-ERV-MIX.
Blueberry
Aphid – Cotton/Melon

The cotton aphid (Aphis gossypii)
The cotton aphid (Aphis gossypii) is a 0.9-1.8 mm small, round aphid with typical black spiracles. The colour varies from light yellow to dark-green, or sometimes almost black. It has a short cauda, no head front knobs, and antennae shorter than the body.

The cotton aphid originates from warmer regions where it is a pest on cotton and Cucurbitaceae. Thanks to the warm climate in greenhouses it can also survive northern winters. The cotton aphid is mainly a pest on greenhouse vegetables such as cucumber and melon, and on ornamentals such as chrysanthemum andhibiscus. Greenhouse strains do not change their host plant. After hibernation in the greenhouse this aphid can become a pest early in spring.

More than other aphid species, populations of cotton aphids can grow very fast. There exist several strains of cotton aphids, each with a specific preference for a certain host and resistance against pesticides.

Ervi

The parasitic wasp Aphidius ervi occurs in most parts of Europe and has been introduced in North America, Argentina, New Zealand and Australia. It looks very much like the related Aphidius colemani, but it is twice as big. Aphidius ervi also has a black, slender body with brown legs and long antennae. Its bigger size is logically related to the fact that it parasitizes bigger aphid species.

Parasitation also occurs similarly as with Aphidius colemani. Once the female has found a suitable host, she bends her abdomen under her legs and injects an egg in the aphid with her ovipositor. During the first days after parasitation, as long as the egg stage takes, the aphid keeps on eating and secreting more honeydew. Adult aphids keep on reproducing progeny. Then the Aphidius ervi larva starts eating the larva from the inside, and modifies it consequently to a golden-yellowish-brown mummy. Finally, a new adult parasitic wasp leaves the mummy through a round hole.

The total development time of Aphidius ervi takes 26 days at 14°C (57°F), 13.5 days at 20°C (68°F) and 12 days at 23.6°C (75.5°F). A female lays about 350 eggs in a life time, of which most are laid during the first 5 to 7 days, at a rate of about 55 eggs per day. Aphidius ervi has a very good searching ability. Also at lower temperatures the parasitic wasps still fly well. Just like other aphid parasites the presence of Aphidius ervi can cause such a panic in an aphid colony, that some aphids fall down and are not parasitized.

Colemani

Aphidius colemani is a slender, black insect with brown legs, long antennae and conspicuous wing venation. Its size depends on the size of the parasitized aphid, but is usually about 2 mm. The female has a pointed abdomen, while the male’s abdomen is round-shaped.

The female Aphidius deposits an egg in an aphid. She bends her abdomen under her legs and injects an egg in the aphid with her ovipositor. This takes only a fraction of a second. The wasp parasitizes adults and nymphs. During the egg stage of the wasp (the first 3 days after parasitation), the aphid even eats more than normal and secretes more honeydew. Parasitized aphid adults or 4th instars keep on producing progeny.

Then, the Aphidius larva starts eating the aphid from inside, starting with the non-vital parts. Seven days after parasitation it fixes the aphid onto the leaf, and forms a silken cocoon which makes the aphid swell. The outside of the aphid becomes golden-brown and leather-like, and is then called a mummy. Four days after the beginning of the mummification (at 21°C or 70°F) an adult Aphidius leaves the mummy through a round hole.

The total development of Aphidius colemani takes 14 days at 21°C (70°F), which is longer than aphid development in optimal circumstances (9 days). However, this is largely compensated by the hundreds of eggsAphidius lays. Most of these eggs are laid during the first 4 days. An adult Aphidius lives for 2-3 weeks.

The parasitic wasp finds aphid colonies from a long distance by “alarm signals” produced by an infected plant. At shorter distance it smells the honeydew. In the presence of an Aphidius in an aphid colony, aphids often secrete ‘alarm pheromones’. The other aphids start to panic, and often let themselves fall down, and usually die on the ground.

Male Aphidius emerge from unfertilized eggs. These are deposited soon after mating or at the end of the female’s life. The ratio females-males is usually about 2:1.