A group of ecologists studied the forest springtail (Folsomia candida) and the needle-shredder beetle larvae (Rhagium species).
The larvae of springtails and needle-shredders live in decomposing pine litter. They compete with each other for decaying organic matter.
Carabid beetles are active predators that feed on both springtails and needle-shredder larvae.
Complete the pyramid of biomass for these feeding relationships, starting from the base provided in the diagram below:
Adult female horseflies (Haematopota pluvialis) normally feed on sugar-rich plant nectar. However, when eggs are developing inside them, they seek out livestock hosts to feed on their blood.
Suggest why the female horseflies show different feeding behaviour when they develop eggs.
Before feeding, female horseflies inject saliva containing anticoagulant proteins that prevent blood clotting at the wound site. Suggest how preventing clotting helps the horsefly.
After the horsefly has finished feeding, the livestock host's immune system responds against the salivary proteins. Antibodies are produced.
Describe how antibodies help the host's body destroy these proteins.
Scientists are investigating biological control methods to reduce horsefly numbers.
They found a symbiotic bacterium species living in the gut of the horsefly larvae that synthesises essential B vitamins for them, while the larva provides a sheltered, nutrient-rich habitat.
What name is given to this type of relationship shown by the horsefly larvae and the bacterium?
The scientists have developed a biological toxin that only becomes active in highly acidic (low pH) environments.
Explain why this toxin could kill the horsefly larvae but not harm other species of soil insect larvae whose guts are alkaline (high pH).