"Lgreen peach aphid (Myzus persicae) is an insect of the order Rhyncotafamilja Aphididaesottofamilja Macrosiphinae. It is one of the most fearsome pesti tas-siġra tal-ħawħ and it is present everywhere in Italy and in the world. In English it is called green peach aphid. Minbarra ħawħ (primary host), the green aphid attacks and damages numerous other vegetable crops (secondary hosts).
To prevent the insect from causing significant losses to crops, it is necessary to intervene in a timely manner and with products allowed in organic farming.
In this article we explain how to act in the right way against this type of aphid.
Description of the green peach aphid
il Myzus persicae presents different vital forms, distinguishable from each other for small details. First we have the shape winged fondatrigenia, of greenish color, except the head, the thorax, the sclerotizations of the abdomen and the siphons, which are brown. The head is provided with a frontal tubercle and converging antennal tubercles. Measures 3.5mm in length, including wings. Then there is the form attera fondatrigenia, green, yellowish or reddish in color, with three darker dorsal lines, antennae lacking secondary sensilli. Measures 1.8-2mm in length.
We therefore have the form attera virginopara exile, always green, or yellow or reddish. The tubercles in smaller numbers or absent than in the aera fondatrigenia, clear siphons, slightly swollen in the distal part. So we have the winged malewith antennas equipped with about 30 secondary sensors.
Finally the form of amphigonic female ather, green in color, except the distal part of the femurs, tibiae and tarsi, which is brown. Siphons slightly swollen on one side in the distal portion. Measures 1.5mm in length.
Bajd
It is also important to recognize the durable egg of the peach aphid, green in color as soon as it is laid, bright black afterwards. The dimensions are 0.6 x 0.3 mm.
Plants attacked by the green aphid
As mentioned, the primary host of this aphid species is the peach tree Prunus persica, hence the name. However, it is a highly polyphagous aphid, which has over 400 herbaceous species as secondary guests, afferent to over 40 botanical families. Among the horticultural species of greatest agricultural interest we have: solanaceae (tadam, brunġiela, bżar ħelu), chenopodiacee (chard u ispinaċi), cruciferous (ravanell u diversi speċi ta kaboċċi), composite (insalati, ċikwejra, smooth and curly endive, ħass), cucurbits (zuchini, ħjar, bowler, dulliegħa, qara, lufa, kiwano) and finally, legumi (fażola, Fażola ħadra, piżelli). Basically, when you see a green aphid on crops, it most likely is Myzus persicae.
Direct damage to plants
On peach trees, green aphid colonies literally invade the leaves, causing them to curl up, then turn yellow and eventually fall off. This causes the development of the shoots and therefore the tree itself to stop.
In nectarine peach varieties, the parasite also attacks small fruit, which grow small and misshapen.
On the herbaceous plants listed above, it mainly invades the underside of the leaves, but often also the flowers. For example, on peppers, which are very prone to attacks by green aphids, leaf infestions cause the deformation of the flap and block the growth of plants, especially young ones.
Indirect damage
In addition to direct damage, green peach aphid is much feared by farmers for indirect damage, as it is a potential vector for over a hundred pathogenic plant viruses. For example, the potato leaf curl virus, the virosis of tomato or that of chard, tobacco, pea, chard. These viroses are usually transmitted late in the season. After the migration of the green aphid to other herbaceous plants there are no particular risks of virosis transmission. In the second migrations, from herbaceous plants to other herbaceous plants, the risk is much greater.
Life cycle of Myzus persicae
The green aphid overwinters as a durable egg on the peach tree. The eggs are mostly laid on the twigs and in the armpit of the buds. The winged founding forms are born precociously, starting from the end of February, at the vegetative restart. Maturity is reached during flowering or when the petals fall. After 15-20 days, the first apothecary foundations are born (partogenesis), which colonize the underside of the leaves. As the spring progresses, the colonies of green aphids thicken and damage to the infested vegetation begins to show.
There are 2-3 generations of founding forms that follow one another in this phase. Already from the second generation the migratory winged forms appear, which are transferred to the secondary guests, making flights of up to several km taking advantage of the windy motions.
Closing the cycle
On herbaceous plants, several generations of deadly and winged forms of the green aphid take place until autumn. In the middle of autumn, on the other hand, within the colonies, the sexupare winged gynopars and the apterous andropars differ. The first ones reach the peach tree and are localized along the rib of the upper page, and then give birth to anphigonic apterous. On the other hand, the apterous androparas generate males who later fly on the peach trees to fertilize the amphigonas. Each of these, from the beginning of October to the end of November and beyond, lays an average of 6-8 durable eggs, thus concluding the holocycle. In areas with mild winters or in protected cultivation, this insect can survive on secondary hosts, especially on brassicas.
Natural antagonists of the green peach aphid
Fortunately, there are several in nature natural antagonists of the green peach aphid. First of all, the ladybugsespecially the species Adalia bipunctata. Then there are other predators, namely: the coccinellida beetles Oenopia conglobata u Scymnus subvillosus; the diptera hoverflies Episyrphus balteatus u Syrphus ribesii; the chrysopid neuropter Chrysoperla carnea; the thrombidid mite Allothrombium fuliginosum. Finally the chalcidoid hymenoptera Aphidius ervi which acts as a parasitoid of the aphid.
The important balancing role played by beneficial insects can only work in environments where biodiversity is high and no chemical pesticides are used. Unfortunately, this condition in traditional peach orchards is difficult to detect.
How to get rid of green aphid
To eliminate the green aphid of the peach tree it is of fundamental importance to act promptly against the first founders and the initial colonies. The best results are obtained by intervening in pre-flowering or immediately after withering. Subsequent interventions on extensive infestation give poor results and require repetition of the treatment. For this reason, monitoring is essential, it is therefore good to carefully inspect the plants and act at the first signs of infestation.
If you intervene in time, on aphid populations that are still underdeveloped, you can use the sapun tal-potassju artabli ssib fiha ħwienet speċjalizzati. This natural soap acts by contact, suffocating the external cuticle of the aphid which is soft.
If, on the other hand, the colonies of the green aphid are already very developed, the best products that can be used in organic farming are piretru naturali (dik easily found on the market) jew ilazadirachtin (dik misjuba fi ħwienet speċjalizzati).
To maximize effectiveness, the treatments should be performed in the evening, carefully wetting the infested vegetation.
Ibda Thread ġdid