Insects 3- Biodiversity and importance

Insects 3- Biodiversity and importance

1. Abundance

   • 20 million ants/ha in tropics
   • 43 ant species in single tree in amazon
   • Tropical forests-- ants and termites have greater abundance than all other combined micro fauna

2. Ecological importance- agriculturalists

   • Leaf cutting ants
     • Crush leaves into compost to grow fungus-- protein source
     • Different jobs for different members of colony
       • Chewers outside colony
       • Workers inside who tend to the growing fungus
     • Two genera
       • Apocrita
       • Acromyrmex
     • Dominant herbivores
   • Harvester ants
     • 35% of seeds of all herbaceous plants est to be distributed by ants
     • Act as both seed dispersers and eaters
     • Harvester termites
       • Hodotermitidae
       • Termitidae
       • Consume 25% of grass in savannas
   • Soil excavators
     • Mix soil and mineral components when making nests
     • Help to break down soil components- feed on it
     • Influence soil properties- Affects soil fertility-- hence plant life-- ecosystem engineers
   • Farming
     • Formicae and Dolichorine farm hemoptera for honeydew
     • Hemoptera have excess honeydew-- ants feed on this
     • Ants protect homenoptera- move them round plants
     • Can cause damage to crops
     • Insects emit methane and Co2 during decomposition of organic matter- 0.2- 2% of global production

3. Social insects as predators

   • Wasps
     • All wasps are predators
     • Most pest species have a wasp predator
     • They have little impact on crops so can be used to prey on pests
   • Ants as predators
     • Scavenge on larger prey
     • Aphropod abundance increases by 80% when formica ants were excluded
     • Army ants
       • 200 species of ants
       • Keystone predators
       • Features
         • Thick appendages
         • tough cuticles
         • Effective sting
       • Can be 1 million strong
       • Predate leaf-cutting ants- a dominant organism

4. Interactions with other species

   • Pollinators
     • All bees pollinate to feed larvae
     • Some wasps accidently pollinate
     • Plants and bees evolved together to work together-- co-evolved symbiosis
     • Tricks to prevent having to produce nectar
       • Look like mate
       • Trapping bees-- exit via the pollen sac
     • 27% of UK endangered species rely on pollinators
   • Invasive species
     • 7 out of top 100 invasive species in the world are social insects
       • Yellow crazy ant-- forms supercolonies
       • Red imported fire ant
       • Argentine ant
       • Common wasp
       • Little fire ant
       • Big headed ant
       • Formosan termite
     • Impacts
       • Compete with, predate and erradicate natural fauna
       • Cause economic damage to
         • Agriculture
         • forestry
         • Buildings
     • Problems on islands
       • Reduce species diversity
       • Eliminate arachnid pops across islands
       • Reduce abundance of flying and tree dwelling insects
       • Galapogos islands- little fire ants eat tortoise hatchlings

5. Economical importance

   • as pests
     • Social insect as agricultural pests
       • Leaf cutter ants
         • One of top 5 agricultural pests in many neotropical countries
         • Eucalyptus and citrus plantations in Brazil-- losses can be 100%
       • Termites (Macrotermitidae-- Termitidae)
         • Main pest of maize in sub-saharan Africa
         • Can cause 30% of yield loss
       • Aphid- protecting ants
         • Agriculture
         • Farming
     • Termites as structural pests
       • 83 termite species are a significant pest
       • Affect 9% of Australian homes--$910 million per year
       • Cost $3 billion per year in USA
     • Spread of disease- in hospitals
       • Feed on wounds
       • Carry pathogenic bacteria
   • As beneficial insects
     • Honey
       • Sugar- important commidity across globe
       • Bee farming
         • Apis mellifera
         • Apis Cerana
       • Harvested from wild Apis dorsata
       • Medicinal
         • Releases hydrogen peroxide
         • Antibiotic compounds
         • Manuku honey- used to treat wounds infected by antibiotic resistant bacteria
     • Other products
       • Propolis
         • Used as sealant in hives
         • Used in medicine and dentistry
         • Car and wood waxes
         • Chewing gum
       • Royal jelly
         • produced by bees by secreting proteins from gland in head
         • used in skin care products
       • Bees wax
         • Food
         • Cosmetics
         • pharmaceuticals
         • Candles
     • Pollinators
       • USA pollination worth $40 billion pa
       • Bumble bees
         • Important pollinators of greenhouse crops
         • Buzz-pollinate-tomatoes require this
         • 60,000 colonies imported to UK each year
       • Native bees sufficient to pollinated 90% of watermelon crop
       • 15-30% of all food in USA dependent on bee pollination
     • Predators
       • Wasps as biocontrol for crop pests
       • Ghana- as effective as pesticides in protecting Cashew crop