Introduction to integrated methods in the vegetable garden
a) After germinating on the surface, the cuscute dodder plants appear as filamentous, spindly vines that wrap themselves around the stems of host plants and parasitise them with suckers. Some dodder plants resemble the rooted bindweed, whose stems also wrap around the stems of other plants.
Polyphagous and oligophagous insects.
Polyphagia is a diet characterised by a choice of different plants that allows pests to survive if one of their preferred foods becomes scarce. Among the insects that are particularly polyphagous, it is useful to mention the following defoliating caterpillars:
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Corn borer (Heliothis armigera, Heliothis zea) also known as tomato borer, as it is also found on tomatoes and can also attack artichokes, cucurbits and legumes.
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The caterpillar of the bramble bombyx (Macrothylacia rubi) is sometimes called "the polyphagous", for its ease of invading other plants including edible species for humans such as strawberry, raspberry, and others.
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The Mediterranean moth (Spodoptera littoralis) originates from Africa and is present in France in the South-East. It thrives on cereal crops (maize, sorghum, etc.), alfalfa, potatoes, green beans, tomatoes, strawberries and other vegetable and ornamental crops. The caterpillars of this pest cause rapid and complete destruction of infested plants.
In the list of polyphagous pests, migratory locusts are known for their catastrophic devastation in Africa, Australia and Asia.
There are many other polyphagous insects, some of which are endemic, such as the aphids described on this website by clicking here
Some insects are restricted to one plant family or genus; their feeding behaviour is then referred to as oligophagy. Oligophagous insects are more numerous than polyphagous insects. One of the best known in vegetable production is the Colorado potato beetle and the aubergine beetle. Lacewings which include more than 35,000 species, are almost all oligophagous. In this large family, we can mention the famous golden beetle. Being more restrictive in their choice of food, oligophagous insects are more vulnerable to their natural predators and parasites, but some of them have developed defence systems to keep them away, notably by producing toxic or foul-smelling substances or both.