Stem-Borrowing Pest

Classification

• These live within the plants stem, often found stunting growth or killing the apical meristem.
• May also infect the roots and leaves
• May be a disease vector

Nematodes

• Stem Nematodes include Ditylenchus and Aphelencoides spp.

Diagram of Ditylenchus Dipsaci



• plant pathogenic nematode that primarily infects onion and garlic. It is commonly known as the stem nematode, the stem and bulb eelworm or onion bloat.
• Live in the roots of the plants to infect their host.
• Symptoms of infection include stunted growth, discoloration of bulbs, and swollen stems.

Coleoptera

Cabbage Stem- Weevil
 

• There's species are more often seen from spring to autumn
• The larvae develops in the stems of the brassicas and then continues its feed from there.
• Widespread throughout England and Wales
• Control used to reduce the amount is by seed treatments of gamma-HCH or Sprays of gamma-HCH, Azinphos-Methyl, Azinphos-methyl + demeton-s-methyl sulphone, chlorpyrifos or triazophos. (GRAHAM and GOULD, 1980)

Diptera

Frit Fly Life Cycle Showing that it is constantly living throughout the seasons

 

• The Frit Fly usually white, yellow and black and are often found in grassy areas.
• They cause damage to new turf by destroying the stems of ryegrass, fescues and bents (use of larvae)
• Adult Flies are attracted to white objects and if a sighting of a large number of these flies could indicate larvae
• Larvae dig tunnels, infect stems and stay through winter
• Fruit Flies can be controlled by chemical sprays

Lepidoptera

Rose Stem Girdler (Species Unknown)

 

• Metallic wood boring beetle
• Flathead larvae is the known youngling of the group they cause the most damage to the rose by borer tunnelling within the pithy centre of the stem.
• Swollen, gall-like area on canes
• Canes with wilted, dried leaves
• Upper portions of canes break off easily during the summer
• Tunnelling in the lower part of the cane
• Boring damage and galleries inside of the cane
• CONTROL; insecticides to kill any larvae and eggs, remove infected plants over the season and over winter  

references;

GRAHAM, C. and GOULD, A. (1980). Cabbage stem weevil (Ceutorhynchus quadridens) on spring oilseed rape in Southern England and its control. Annals of Applied Biology, 95(1), pp.1-10.

Soil/Root Dwelling - Homoptera

Cabbage Root Maggots

Cabbage root maggot flies are delicate, hump backed grey-brown flies, about 5-7mm long. Cabbage maggot flies are difficult to distinguish with the naked eye, but each will only be found on their appropriate family crop.

Cabbage Root maggot infesting a cabbage under a microscope.



• Small, white bullet shaped eggs are laid in the soil to form maggots which are white and legless they are found in the roots and around the roots as well.

This image shows how cabbage root has affected roots to the crops hugely and reduced the roots making it unable for growth. On top of this, the plant is parasitic for human consumption.

Onion and seedcorn maggot flies are very similar! 

Soil/Root Dwellers- Mollusca

Classification;

• Plant-boring pests- Attack the plants roots, tubers, bulbs, rhizomes or the basal regions of the stem
• Some are disease vectors
• Above ground feeders- on the leaves above ground in wet weather or dark phase.

 What do they do?

• Shred organic material
• Stimulate microbial activity
• Mix microbes with their food
• Mineralize plant nutrients
• Burrow
• Stimulate the succession of species
• Control pests

Predator

Micro-predators can be either feed on different prey or specialists, hunting only a single prey type. Predators include anything from centipedes, spiders, some mites, ground-beetles etc. Many predators eat crops pests and some have been developed for commercial bio-controls an example is parasitic wasps.

Predatory Mites Prey on nematodes, other mites and larvae of insects

Shredder

Seen in the soil surfaces. Chew up the dead plant matter as they eat bacteria and fungi on the surface of the plants. most abundant shredders are millipedes and sowbugs etc. These can become pests by feeding on living roots if sufficient dead plant material is not present. 



Sowbugs; powerful mouthparts used to fragment plant residue and leaf litter.

Herbivores

Numerous root-feeding insects. Mole crickets and anthomyiid flies (root maggot) just being 2 examples. some herbivorous such as rootworms can be crop pests where they occur in large numbers. they feed on roots and other plant parts

The Symphylan, relative to the centipede, feeds on the plant roots and can become a major crop pest if its population is not under control.

Fungal Feeders

Arthropods that graze on fungi includes some mites and silverfish along with springtails. they consume bacteria and fungi off the root surfaces. they are a pest in plants as they are a fraction if the loss in plant nutrients and the nutrients release by fauna

Pale-coloured, blind springtail is a typical fungi feeder. they live deep in the surface layer of natural and agriculture soils throughout the world

Soil and Root Dwellers- Nematodes

Classification;

 

• Plant-boring pests- Attack the plants roots, tubers, bulbs, rhizomes or the basal regions of the stem
• Some are disease vectors
• Above ground feeders- on the leaves above ground in wet weather or dark phase.

 

Nematoda; A virus Vector

• They are free-living
• Attack the outside of the plants (ectoparasitic)
• Live within the plant as well (endoparasitic)
• These can be classed as either migratory (Moving around form to one place to another) or sedentary (staying in one place)  

Example; Xiphinema spp. (Dagger nematodes)

 

 

This is a soil food web which shows how nematodes are put into the system as a vector under the soil and into animal species as well.

 

 

 

Root-Knot nematodes are plant parasitic nematodes. They exists in the soil where the areas are hot in climate or winters are short. About 5% of global crop loss is due to this nematode, the root-knot development drains the plant's photosynthetic material and nutrients.

Root-knot has a huge economical impact damaging plants and field crop. These nematodes are distributed worldwide and are extremely difficult to control.





Root Knot; Before and After







The 3 Strategies of survial

K- Strategist

• Stable environments are labelled by species with a K-strategy

Such animals tend to large, long-lived and invest a large amount of energy into rearing their offspring ensuring they have a higher survival rate.

Elephants are within the  K -species as they rear for their young to induce a higher survival rate therefore most of their energy is placed into that instead of surviving the unstable conditions they have adapted to K-strategist.

Population levels tend to remain stable

(More related to mortality then environmental influences)

R- Strategist

• Fluctuating Environments are labelled by species in the R-strategy

These tend to be small, short-lived species. whom invest all their energy in producing more offspring then the K species, the population density can get low due to parental care being minimum.



Mice are within the R-strategy as they have so many offspring that minimum care can be giving to all off the offspring from the mother therefore she actually produces a low density due to deaths at young ages.

Low survival rates but tend to maximum use of temporary environments

A table showing the Differences between R and K;

 

Table show the differences between R and K

The graph above shows lifespans of fish which is a R species therefore has a short lifespan but higher density (Blue line) and Dugongs which is a K species which population level tends to remain high therefore it lives longer (red line)

Bet-Hedging

• Bet-hedging strategies alter strategies according to their environment

some spread their life histories over variables time periods, others respond to their environments by laying eggs and then moving on.





the graph above shows how bet hedging works the growth of the plants is unpredictable by fitness as the plant is using mechanisms of change to survive in unpredictable circumstances.

PESTS! - MAINLY R-STRATEGISTS.

Reproductive stratgegy Theory of Pests

There is the theory that species adopt one of the 3 life strategies in order to survive in a stable and unstable environment.


either of the 3 strategies are below:

1. r-section
2. k-selection
3. bet-hedging

But, What is a Stable environment?

Well it is not the UK! Stable environments are those climates that are relatively constant or easily predictable in there weather and other areas as well for example the tropical rainforest has a constant temperature of around 5/6 degree and a known mist of fog. Therefore, this is a stable environment.




Temperature zones for the Rainforest live on the 27/04/2017

So, What is a Unstable environment?

This is more like the UK, it is an unpredictable environment which varies in it climates. as well as this there is disturbances in the temperature zones.

Temperature Zones for London showing rain in the evening live on 27/04/2017

Therefore Pests need to adapt to the environments by inhabiting to one of the 3 strategies above.






Go to the next Post to Find out more on the Strategies

What is a Pest?

What is a pest?


A troublesome and destructive animal or thing.

Types of Pests:

1. Nuisances
2. vectors
3. competitors of food products for human or livestock consumption.

Competitors- insects that are mainly mankind's biggest threat  



Nuisances- After death the growth of Bactria will grow of this species.  

Vector- carry of diseases to animals of plants