NEWS

Not all insects are bad for the garden, but exercise care in introducing them

Chemicals are still used to eradicate garden pests, but they can be dealt with far more safely by introducing their natural predators that don’t harm plants. The most common garden pests in Greece are the whitefly, spider mite, thrips, leaf miner, caterpillar, mealybug, sciara and vine weevil. Beneficial insects include different kinds of parasitic wasps, predatory bugs and mites, entomopathogenic fungus, gall midges and lacewings, all of which are available at some garden supply stores. Some occur in nature. These beneficial pests do not harm the plants, animals or humans, but they should not be introduced indiscriminately, and it is best to seek expert advice so as not to upset the garden’s natural equilibrium, according to horticulturalist Antonia Moutafi, who has been using them since 1992 in her own work at the Epi Gis garden center and in advising clients. «A few of my more informed customers order beneficial insects from us, as well as other organic supplies,» Moutafi told Kathimerini English Edition, «Only after a study (of the site) should an experienced and responsible horticulturalist release these beneficial insects, so as to maintain the natural equilibrium,» she said. Once they have been introduced, any use of pesticide will kill the insect’s natural predators as well, leading to a vicious circle in which pest populations can re-establish themselves. This creates a need for yet more pesticides that pose health risks, particularly to children, who are the most likely to be exposed to those used on lawns, putting them at higher risk for diseases such as asthma and even some cancers. «It’s basically about monitoring, otherwise you can be too late. By the time red spider mites are really noticeable, it’s too late to introduce beneficial insects,» said horticulturalist Piers Goldson. «You can get rid of red spider mites by spraying with water, saving yourself a lot of money. But you have to keep watching your plants for pests. Integrated pest management is a complex issue.» Another reason for getting expert advice before you go ahead and buy beneficial insects is that some of them are very sensitive. «You have to consider their shelf life,» said Goldson. «Also the effect of beneficial insects depends on the stage of the pest’s life. A ladybird can eat many more aphids a day if they are at the juvenile stage, rather than the adult stage.» «Some of these beneficial insects occur naturally here in Greece, such as ladybirds, that feed on aphids, and a species of beetle that eats mealybugs,» he added. It is important to have a variety of plant species that flower at different times of the year if you want to attract beneficial insects to your garden. Apart from pest insects their diet also includes nectar and pollen, and at some stages of their life cycles this is what they survive on. Small trees and shrubs as well as perennial and annual weeds provide beneficial insects with an early food supply. So weeding should be selective enough to allow a few to remain in the garden. It is also important to have plants of different heights. Lacewings lay their eggs in shady protected areas and ground beetles need the cover of low-growing plants. Attractive plants Some plants attract more beneficial insects than others. These include fennel, angelica, coriander, dill and wild carrot all of which have the tiny flowers required by parasitoid wasps. Various clovers, yarrow and rue also attract parasitoid and predatory insects. Low-growing plants, such as thyme, rosemary, or mint, provide shelter for ground beetles and other beneficial insects. Daisy, chamomile and mints will attract predatory wasps and flies. The wasps will catch caterpillars and grubs to feed their young, while the predatory and parasitoid flies attack many kinds of insects, including leafhoppers and caterpillars. Of course if you haven’t ever used pesticides in your garden, and already have a wide variety of plants (or perhaps even practice companion planting – using plants that protect each other from pest infestations, such as planting garlic next to rose bushes), you may already have a natural balance of insects. Chrysanthi Parayou, who has a large nursery of native plants in Pendeli, said she uses absolutely no pesticides and has had negligible losses through pests. Sally Razelou, who looks after the garden at Sparoza, Koropi, also said that if a plant is damaged by pests, «it usually grows back again the next season.» Jennifer Gay, in her book «Greece, Garden of the Gods,» has a whole chapter on controlling pests and diseases the holistic way. «The goal is to encourage desirable growth within a harmonious framework of other life forms,» she writes. «A garden without any insects or fungi would soon become unhealthy. Troubles arise when any one factor gets out of balance, allowing a predominance of destructive beasts.»