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What Works in Conservation 2018

William J. Sutherland
Lynn V. Dicks
Nancy Ockendon
et al.

11. Some aspects of enhancing natural pest control

11.4. Perennial farming

Texte intégral

Likely to be beneficial

● Exclude ants that protect pests

1 Parasitism: One of two replicated, controlled studies (one also randomized) from Japan and the USA found greater parasitism of pests by natural enemies when ants were excluded from trees. The other study found greater parasitism at one site but no effect at another.

2 Natural enemies: Five studies (including four randomized, replicated, controlled trials) from Japan, Switzerland and the USA found effects varied between natural enemy species and groups, sampling dates, sites, crop varieties and ground cover types beneath trees.

3 Pests: Three of seven studies (including four randomized, replicated, controlled trials) found fewer pests and another found fewer pests at times of peak abundance only. One study found mixed effects depending on date and other actions taken simultaneously (predator attractant and ground cover treatments). One study found no effect.

4 Damage and tree growth: One study found no effect on damage to tree foliage but one study found greater tree growth.

5 Ants: Six studies found that glue or pesticide barriers reduced ant numbers in tree or vine canopies. One study found that citrus oil barriers had no effect.

6 Crops studied: cherimoyas, cherry, grape, grapefruit, orange, pecan and satsuma mandarin.

7 Assessment: likely to be beneficial (effectiveness 40%; certainty 50%; harms 12%).


Unknown effectiveness (limited evidence)

● Allow natural regeneration of ground cover beneath perennial crops

9 Natural enemies on crop trees and vines: Five studies (including one replicated, randomized, controlled test) from Australia, China, Italy and Portugal compared natural and bare ground covers by measuring numbers of natural enemies in fruit tree or vine canopies. Three found effects varied between groups of natural enemies, two found no difference. Two studies from Australia and France compared natural to sown ground cover and found no effect on enemies in crop canopies.

10 Natural enemies on the ground: Five studies (including three replicated, randomized, controlled trials) from Australia, Canada, China, France, and Spain compared natural and bare ground covers by measuring natural enemies on the ground. Two studies found more natural enemies in natural ground cover, but in one the effects were only short-term for most natural enemy groups. Three studies found mixed effects, with higher numbers of some natural enemy groups but not others. Two studies compared natural and sown ground covers, one study found more natural enemies and one found no effect.

11 Pests and crop damage: Four studies (three controlled, one also replicated and randomized) from Italy, Australia and China measured pests and crop damage in regenerated and bare ground covers. Two studies found fewer pests, whilst two studies found effects on pests and crop damage varied for different pest or disease groups. One study found more pests in natural than in sown ground covers.

12 Crops studied: apple, grape, lemon, olive and pear.

13 Assessment: unknown effectiveness (effectiveness 35%; certainty 29%; harms 20%).


● Isolate colonies of beneficial ants

15 Natural enemies: One replicated, controlled study from Australia found predatory ants occupied more cashew trees when colonies were kept isolated.

16 Pest damage and yield: The same study found lower pest damage to cashews and higher yields.

17 The crop studied was cashew.

18 Assessment: unknown effectiveness (effectiveness 60%; certainty 19%; harms 0%).


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