- Emirhan Turan
Beneficial Insects and Mites - I
By Emirhan Turan, April 5, 2021
Not all insects and pathogens are harmful to our plants, some are saving our crops from harm. Beneficial organisms are grouped mainly as insects, pathogens and nematodes. This article is focused on beneficial insects that are mostly targeting aphids and whiteflies.
Beneficial insects are the main pest control agents on organic production. For years different insects and predators were used to achieve convenient results. Even though the insecticides, herbicides, fungicides are more effective, the results of these beneficial insects cannot be ignored. There are two main groups of beneficial insects:
-Predators that attack and eat the harmful insects;
-Parasitoids that kill the insect with laying eggs on or in the harmful insects.
However, there are more groups of beneficial insects such as, weed eaters, pollinators etc.
Lady-bugs (Coccinellidae) are mostly known as bringing luck to us. However, these small bugs are more beneficial than they look. Adalia bipunctata (two-spotted ladybug) is a coccinellid beetle that can be found very easily in nature and they are used in organic production as aphid predators in fruit trees, vegetables and ornamental productions. A grown, adult ladybug can eat over 100 aphids. The females lay their eggs close to aphid colonies, so the new hatched larvae can find enough food effortless. They can be distributed to the field if the aphid attack is in the beginning, or can be put on the hotspots where the aphids are dense.
Aphidoletes aphidimyza commonly known as aphid midge is a predator in the Cecidomidae family. It can hunt over 70 different aphid species. They are using spider webs to protect themselves while mating and the later the female lays the eggs where she finds the dense aphid colonies. They are active during the night time and hiding under leaves during the day. They like mild temperatures and the larvae can kill more amounts of aphid than they need to feed.
Chrysoperla carnea known as common green lacewing is an aphid predator that is efficiently hunting the green aphids. Green lacewing can eat the aphids only when it is in the larva stage while during the adult stage it is fed by sugar sources in nectar, honeydew etc. The female lays the egg in the middle of the aphid colony. A developing larva can hunt over 200 aphids. The larvae inject enzymes into the victims bodies which digest the internal organs and kill them. Green lacewings are resistant to temperature fluctuation and show good flexibility to changing conditions while hiding, and appearing when they find a suitable environment.
Another predator from the Coccinellidae family is commonly known as 14 spotted ladybug (Propylea quatuordecimpunctata). It can be found commonly in European regions. Propylaea is a good bio-control agent as it hunts the aphid colonies even when they are in low density.
Aphidius ervi is a parasitoid which targets various aphid species. A.ervi is an unaided parasitoid and performs the entire larval cycle within one aphid. The female has a capacity to find the suitable aphid to lay eggs. The important point is that the aphids are not killed directly but they are being used like a host and eventually the characteristic is turning to brown ‘’mummy’’.
Amblyseius swirskii is an effective predator for whiteflies. These mites are originating in the Mediterranean regions and are very well suited for hot climates. A. swirskii is a general predator that feeds with pollens but also the eggs and young stages of whiteflies. In the warm and bright seasons, they can easily reproduce in various vegetables like aubergines, cucumbers, peppers etc. In the presence of pollen or live prey the development stage can be faster.
Delphastus catalinae is a predator of whiteflies originating from the American continent, however, was established in southern Europe as well. It is able to feed on all whitefly stages, but preferably eggs and larvae. D. catalinae prefers warm or temperate areas where it’s able to establish in a stable manner. This predator can be used indoors and outdoors in various whitefly species on ornamentals, vegetables and fruits.
Macrolophus pygmaeus is a beneficial bug and a good predator of whiteflies and Tuta absoluta. All stages of M. pygmaeus are very mobile and can hunt different whiteflies species. Both larva and adults of Macrolophus pygmaeus can hunt different stages of whiteflies which makes them convenient as a predator. The predator is preferring tomatoes, however, can be used in eggplant, pepper and some ornamentals as well. Another advantage of Macrolophus is durability. They survive even with low food availability and once they are established they can resist bad conditions even with fluctuation of temperature. During their development they can use aphids, mites, leafminers and moths as food sources.
Eretmocerus eremicus is a tiny wasp that is parasitizing young stages of whiteflies. E. eremicus attacks whiteflies including greenhouse whitefly (Trialeurodes vaporarium), sweetpotato whitefly (B. tabaci), silverleaf whitefly (Bemisia argentifolii), and banded winged whitefly (T. abutlonea). E. eremicus is susceptible to pesticide residues and fumigants. Releases of E. eremicus will be effective in crops that have not been sprayed for at least 10-14 days. The female is laying around 50 eggs in optimal conditions and when the larvae appears it penetrates to host and kills them when they reach pupal stage.
Encarsia formosa is a tiny wasp and parasitoid of greenhouse whiteflies that have been used as a biocontrol agent since the 1920s, particularly on tomato crops. They can be used also in ornamentals and any other horticultural crop for biological control and pest management. The female is inserting the eggs inside the host and the egg develops and changes the color of host to black in about 10 days. After the end of the larva cycle, the adult E.formosa opens a hole to get out from the target host. Females lay 50-100 eggs individually inside the bodies of pupae of the host species.
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Main picture by Emirhan Turan, 2020