Types of Pests

Types of Pests

Insect pests.

These are the commonest and most successful pests

Reasons why insects are the major successful pests

  • They  have  high  rate  of  reproduction to  ensure   survival
  • They have short life cycles and so increase in numbers very fast.
  • Presence  of  a  cuticle  that  prevents  water  loss and  protects  insects  against  water  chemicals.
  • Small in size  and  therefore Not easily detected by predators.
  • Require little space.
  • Require little food and produce energy.
  • Have  an exo skeleton that  protects  the  inner  organs   against mechanical damage , maintains a small size, discourages predators from feeding on them, provides  camouflage     gainst  predators.
  • They  secrete uric acid  which  requires  little  water  for  excretion hence  preserving  water   in their  bodies.
  • Most of them feed on a wide range of materials.
  • They  are easily adaptable  to  the  changing  conditions i.e  they  have  lived  on this earth    longer  than  any other  organism.
  • Have defensive mechanisms e.g stings, spines and their legs pungent chemicals against enemies.

Nematodes.

These are legless, tubular, with round un segmented bodies.

The parasitic  nematodes  have  stylets for  piercing  and  sucking  of  plant  sap , e.g  eel worms

Symptoms of Attacks By Nematodes

Root  knots

Excessive branding of the root tips.

Witting and whethering of leaves.

Retarded  growth

Necrotic  lesions

Ways through Which Nematodes Are Spread

  • Rain splash
  • Irrigation water
  • Infected plant materials
  • Soil transfers

Rodents e.g. rats, squirrels, field mice, mole rats.

They have specialized teeth for gnawing and crushing.

They can grind hard materials e.g grains.

Birds

These mainly eat e.g quela  quela

Mites

They lack wings. They attack citrus fruits, tea, and cotton.

When mites attack crops, the leaves turn yellow or brown and later fall off. e.g moulds, yeast. They     sometime cause diseases.

Bacteria

These attack crops and cause disease e.g.  banana bacterial wilt.

Viruses

These  are  tiny and  only  capable  of living  when  inside  living  tissues  of   hosts e.g  cassava mosaic, g/nuts rosette.

Fungi

They are either parasitic or saprophytic

Damages Caused By Pests

They destroy seeds hence interfering with germination e.g. bean, bruchids.

Reduce seed production by attacking flowers.

Destroy growing   parts and cause distorted growing of crops.

Tunnel inside crops and interfere with transport and nutrient absorption.

Eat leaves and reduce the rate of photosynthesis.

Biting pests attack roots and cause loss in water and nutrients absorption.

Remove stored food in tubers, corns and other storage structures e.g rate.

Suckling pests remove   plant sap and cause loss in plan vigour e.g Aphids.

Inject saliva which is toxic to plants.

Cause crop loss by contaminating products with waste and hence poor quality output.

Increase costs of production because their control is expensive.

Transmit disease – causing organisms e.g fungi and bacteria.

Make harvesting hard by destroying   crops especially when   mechanical harvesting is to be used.

Methods of Pest Control

  • Cultural method.
  • Biological control
  • Mechanical / physical
  • Legal control
  • Integrated pest management (IPM)

Cultural Control

This involves the conrol of pests using agronoic practices that include the following;

Early planting of the crop;This makes the pest survive pest attack and icrease its resistance for the pest

Use of closed season(dead season);This is a period during which the growing of a given crop is stopped so as to remove pests and disease build up.

Croprotation;Crops which are susceptible to pest attack should be rotated with those that are not easily attacked

Growing of resistant crop varieties which are able to withstand the effects of pests

Rogueing i.e the reoval of diseased plants or infected plant parts in the garden and consequently burning them

Use of clean seeds where by oly certified seeds that are dressed against pests should be planted

Mulching;some mulches like banana leaves used in the mulching of banana plantations help to trap banana weavils

Trapcropping where by a minor crop that resembles the main crop but when it is planted for the purposes of preventing pests fro entering the main garden

Destruction of the alternate host e.g weeds should be destroyed by weeding because they harbour pests

Mechanical/Physical Method

  1. Physical destruction by picking and destroying of pests
  2. Use of physical barriers
  3. Suffocation i.e use of gas carbondioxide
  4. Use of extreme temperatures i.e vryhot or very cold
  5. Use of scare crows

Biological Method

This involves introduction of other living organisms that are either parasites or predators ued to destroy pests by feeding on them

Qualities of a good predator

It should have a high ability to run after a pest with in plants so that all plant parts are protected

It should have a high reproductive rate so as to out compete the pests population

It should not be dangerous to the farmer or user in the field

It should be harmless to crops being protected i.e should not inject poisonous substances to crops

It shouldnot eat other predators it comes int contact with

It should be able to destroy more than one pest type in the field

It should be resistant to the existing environmental conditions

Chemical Method

This involves use of pesticides that are harmful to the targeted pests.It can be applied through spraying,dusting or fumigation of a crop using sprayers or dusters