Guatemalan Potato Moth
Guatemalan Potato Moth, Guatemalan Potato Tuber Moth, Potato Moth
A Guatemalan Potato Moth is a highly destructive insect, to potato tubers in particular, hence their names. This species is of economic importance because they can ruin entire yields. These insects attack the tubers only; where larvae burrow deep within to the fruit creating numerous galleries that eventually become larger as the larvae get bigger. To make things worse, these insects are highly resilient, adapting to new climates almost effortlessly. They're challenging to detect too. Keep reading to learn more about the symptoms associated with this pest.
A major pest that can be economically significant if weather conditions are permitting.
These insects are of most risk to agricultural industries.
Adults are small (roughly just under 2cm), elongated and thin-winged moths. In terms of their colouration and patterning, they're a drab insect. Colours include a mixture of greys and brown marbling. When at rest, the wings folded, forming a point similar to the roof of a house. Larvae are maggot-like, but possess heads and small legs. They're almost transparent, with dark brown heads. Eventually, the maggot-like larvae form dark spots that cover the body, turning purple on top with greenish-white colouring on the sides. They'll reach the maximum 17mm in length. Pupae (cocoon-structures) begin light brown, eventually darkening with age. The eggs are smooth, yellow, with an iridescent tinge. They're laid in clusters, but can be extremely difficult to see with the naked eye.
After hatching, larvae piece the skin of potatoes and burrow inside. The more they proceed into the tuber, it's sometimes possible to see food residues and excrement exude from the channel openings. With time, secondary rotting begins to effect the tubers. Sometimes it's possible to detect an infestation early. This is done by comparing the weight of potatoes. If light, it's likely they're infested. Be careful before storing potatoes. Early infestations can go unnoticed, leading to a re infestation of potato stores. Tuber holes free of debris mean the larvae has left the potato to pupate in the soil. Factors such as the current climate and the amount of crop can contribute to the severity of an infestation.
This pest has now been recorded from locations in Europe, Central America and South America.
It's possible to buy pheromone-baited traps that can help a gardener or farmer determine the abundance level of the adult moth. Not only this will aid reducing the numbers present, but capture the males- if they can't mate, females will be less reproductively successful. These moths lay eggs on the soil, which larvae burrow within once hatched. Soil kept well-watered makes this more difficult for the larvae. Likewise, by burying the potatoes deeper when planting, you'll make the initial journey longer for larvae, or extra wet soil will drown them completely (even better!). Covering tubers with plastic sheeting is also an effective technique used by farmers. The latter point is especially worth-while if the soil is loamy. Larvae drown in moist soils, so regular watering is emphasised. If possible, sowing dates should be postponed if a bout of dry weather is predicted. These conditions can help this insect multiply at incredibly quick speeds. If there is a current dry period, it's advised to harvest tubers promptly before generations can multiply even more. It's possible to plant varieties which can be harvested earlier in the season, which can help reduce the severity of an infestation. Any tubers left over should be removed and disposed of appropriately as these are very likely to be infested. Infested potato stores are one of the primary causes of an infestation. Before potato tubers are stored, be sure the containers/bags used are sterile.
By incorporating a trap into potato stores, you can attract any males who may have persisted and avoided treatments. Unfortunately, there's currently no appropriate means of chemical control.
These insects are restricted to plants in the Nightshade family. They're most damaging when in an agricultural setting, particularly when in fields of arable crops.