The following selection is from Sally Morgan ’s new bookThe Healthy Vegetable Garden : A Natural , Chemical - free overture to Soil , Biodiversity and Managing Pests and Diseases(Chelsea Green Publishing , September 2021 ) and is reissue with permission from the publisher . Chelsea Green Publishing
Natural Predators
Our garden are home to many raw predators , from the conversant ladybirds and spiders to the less familiar rove beetle and parasitic wasp . These innate predators , or ‘ beneficials ’ as they are call , are your first logical argument of defensive structure .
Natural predators are important in all habitat , natural and artificial . In nature , the population of white Anglo-Saxon Protestant , ladybugs , spider and birds have long regularize the abundance of pests . For example , in a stable forest ecosystem , marauder keep 90 percent of the arthropod herbivores below eruption levels . Spiders hold Douglas fir tussock moth caterpillar and birds will prey on gypsy moths . Under normal condition , predatory animal can prevent outbreaks when pest numbers are miserable to moderate , but problems can arise when there is a variety in the atmospheric condition or a natural tragedy , such as a fire , outpouring or drought , which make the remainder between the target and marauder to be disrupt .
The Predator-Pest Balance
Much research has been convey out on plague - predator relationships and it is clear that systems with a low biodiversity are particularly vulnerable to pest outbreaks . This is what we must endeavor to avoid in our gardens . In my own growing distance , I am aiming for a mosaic of habitats in edict to attract a wide-cut range of beneficials to feed on different types of pesterer . Over the last 10 years , I have seen a unwavering addition in biodiversity and now it ’s not strange for me to wander around the garden and discern a variety of predators . I still have pestilence , of row . In order for these predators to thrive , there must be some quarry animals , so I have had to larn to live with low grade of pests to keep my beneficials feed ! A key challenge , though , is to check that that there are enough predators around betimes in the growing time of year to master the problem aphids , whitefly , cherry-red spider mite and various larva , so that their numbers do n’t spiral out of control . The extremum season , as far as gadfly in the garden are concerned , is early summer , so you involve the beneficials to breed rapidly to take advantage of the solid food bunce , and this needs to continue through mid - summertime . you’re able to achieve this by empathize their life cycles and dietary requirements as well as leave the good plants and over - wintering habitats to enable them to thrive . Clearly , it ’s also very important to be capable to name piranha at each stage of their life history cycle .
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Don’t Overreact
It ’s of import not to overreact when you see plague . For example , you might notice that your wide beans are smother by blackened fly and determine that you call for to do something rapidly to foreclose serious damage to the crop . But this is where you have to be careful . If there are circle of prey around , it is probable that you already have increase numbers of predators , as the predators will imprison behind the prey in the universe bet . If you are tempt to ‘ take the nuclear option ’ and use a chemical substance atomizer , you may well take out both target and piranha and , in doing so , you will demolish the rude cycle and wo n’t then have any chance of being able to get back some born control . It is effective , if you’re able to , to be patient , let nature takes its course , and wait for the predators to ‘ kick in ’ . If you ca n’t wait , check cautiously for any predators on the plant before using an constituent product or simply habituate your finger to take or squash the pests .
Parasitic Predators
I once read an clause that describe the actions of the parasitoid WASP as being far worse than any science - fiction film ! The scene of the animal burst out of its live host in the film Alien may seem far - fetched , but it is happening every day in your garden , albeit on a much smaller scale . There ’s a immense range of leechlike predators , or parasitoids , in the garden . The adult hold out a normal , self-governing life , but their larvae hatch inside another bread and butter organism , consume it and growing . This profit our garden if the server is a pest species . commonly , the host dies as or before the parasitoid emerges to survive their grownup life . Among the most plebeian parasitoids in the garden are parasitic flies and wasps . Some parasitize a grasp of hosts , while others seek out specific innkeeper . The larvae feed on the host and then pupate , either inside or out , before emerging as an adult . The grownup broadly feed on nectar and pollen .
Parasitic Flies
These are not the annoying houseflies and bachelor’s button , but bristly vaporize that are mostly grey - lightlessness in color , with short antennae and Brobdingnagian eyes , but no biting mouth parts . They lay their testicle on leaf , so the master of ceremonies either feed the bollock or the newly hatched larvae as it feeds . They parasitize hosts such as caterpillars , sawfly larvae and leatherjackets . Once the legion dies , the larva carry on to eat on the remains before pupating and over - wintering . One of the UK ’s largest flies is Tachina grossawhich parasitizes caterpillars ; it is so large that it is often mistake for a black humblebee .
Parasitic Wasps
wasp and bee belong to the order Hymenoptera : insects with two brace of wings and a distinctive minute shank . There are Apis mellifera , bumblebees , solitary bees and social wasps , but remarkably , of the UK ’s 7,761 species of Hymenoptera , around 6,500 are parasitoid . Parasitic wasp depart enormously in size , ranging from a millimeter to 30 mm ( 1¼in ) long . Many females have an ovipositor , a sting - comparable adherence at the end of the belly , which is used to pierce the body of the host and lay bollock . Their hosts are mostly butterfly and moth caterpillars and pupae , and sawfly larvae .
It ’s easy to discern the bombastic Ichneumonids , but the little wasp tend to go unnoticed . Both live our gardens . Like parasitic tent-fly , the parasitic wasps can assault the eggs , larval and adult level of the legion . Once the parasitoid egg hatching , the larvae provender on the innkeeper ’s body tissues , taking the fat stores and non - essential organs first , as they do n’t want the host to die too presently . Once their larval microscope stage is complete , they pupate . Some will pupate outside the utter legion , others inside . Among those most ordinarily see in gardens are the bantam braconid parasitoid Cotesia glomerata that wait like a flying pismire and parasitizes the Caterpillar of the large white butterfly stroke .
Chalcid Wasps
Chalcid WASP ( say ‘ kal - sids ’ ) are just 3–9 millimetre ( ⅛–⅓in ) in length . you may identify them from the swollen thighbone on the hind pair of leg and their glistening metal colors . Because of their size , the number of chalcid wasp WASP is often underestimate , but they are improbably useful . They lay their eggs in the eggs and larvae of flies , mallet , moth , butterflies , leafhoppers , thrip and scale insects . Occasionally , you may spot one tapping leafage surfaces with its antennae in lookup of their host ’s ‘ scent ’ , but the bearing of macabre or dead hosts is a certain sign you have a healthy universe of chalcids . Many of the modest parasitic WASP are used as biocontrol in glasshouses .
Social Wasps
Not the most pop of insects , but we demand to encourage this insect because it ’s such a useful predatory animal ! There are eight species of social wasps in the UK , and they are both pollinators and predators . Their life rhythm lead off in autumn , when a paired queen hibernates in holes while the rest of the dependency dies . She becomes alive in spring , regain a nest site , and protrude building the nest and lay eggs . Four calendar week later , the first genesis of prole emerges . The worker track down for insect , especially caterpillars , to feed to the larva , while the workers themselves feed on the sugar - deep secretion of the larvae . societal wasps are worthful predators in the garden , as they serve to command the numbers of insect pesterer . But , by late summer , there is a decline in the number of wasp larva and the provision of intellectual nourishment for the workers dry out up . Then they have to seek out moolah , which lead in damaged fruits and battle with people .
Spiders
Spiders are generalist hunting watch and have a wide-ranging diet . One important fact is that they run to kill more target than they eat , so they are unbelievably useful in spring when they can bound their prey ’s other population growth and in the main exert a stabilizing gist . A garden can have a surprising diversity of spider , which is important since the failure of one species wo n’t dissemble pest control if there are others to take its place . you may hike wanderer diversity by covering the grime with mulch , specially wheat , and establish log wad and germ hotels .
Centipedes
The fast - moving centipede is recover in leaf litter , under toilet , logs and in the compost heap . centipede use their jaws to interject a paralyzing venom into their prey . It ’s easygoing to differentiate between the centipede and the closely concern millipede , as centipedes have a single brace of legs per segment while millepede have two . Even millipedes are not harmful ; they mostly eat beat and decaying matter , which is why they are found under the bark of rotting logs and in the compost heap , so they have a useful theatrical role to act . It ’s only occasionally that they will be invite to feed on seedlings .
Earwigs
This invertebrate has a short repute but , on balance , it is broadly good and add to the predator diversity in the garden . Many nurseryman trap earwig with overturned corpse pots on sticks stuffed with straw , specially around Dahlia pinnata because they can damage the peak bud , but their welfare far overbalance their disadvantage . They are scavengers , predator and pollinator . They fee on idle and disintegrate matter , for the most part , but they will also predate on aphids , snails and other pocket-sized pests and help to moderate codling moth on yield tree . If earwigs are make a problem around your young crops and bloom beds , use live traps and move them to a logarithm mountain .
Amphibians
batrachian fair game on slugs and escargot , grasshopper , ants , flies and other invertebrate animals . They live away from water system as an adult , digging out a shallow burrow in which to shelter and overwinter in deep leaf litter and log piles . You will also find anuran in compost heaps , so it ’s essential to do a toad check before you stick your fork in it . salientian are interchangeable in many respects to frog but are more agile , and they eat a similar range of target . They hibernate over winter in pond mud or under piles of logs , stones and leaf bedding material . Both frogs and toads need piss to multiply so , if you need to advance frogs and anuran , then building a little pond is the response .
Reptiles
If you live in a more rural domain , it ’s not rare to find grass snakes , slow worms and lizards in the garden . I have found grass snakes under voltaic pile of compost in the hoophouse , and gardener frequently report seeing them under sheets of metallic element and find their ballock in compost heaps . sess snake are utilitarian predators , eat insects and small mammals , but they do take batrachian and toads , which make up the bulk of their diet . dull worms emerge from their shelter at crepuscule or after rain , to prey on insects , slug , snails , louse and spiders .
To boost reptile , you need to provide an assailable gay spot where they can bask in the sun . I put down corrugate metal sheets and broken piece of slate , which grass snakes and dull worms can sun themselves on or shelter under . lounge lizard enjoy a gay wall or pile of John Rock in a sunny topographic point . The warmth of a compost heap will attract the reptiles , too . consider about hibernation places as well , such as an undisturbed stack of rock , lumber pot or pile of parting .
Chelsea Green Publishing
