Archive for the ‘insects’ tag
Tobacco plants change pollinators to ditch worms
Sure, the hawkmoth does a good job of pollinating the plant, Nicotiana attenuata, which grows in the Western United States and flowers at night. But the hawkmoth has this annoying habit of leaving behind its eggs, which develop into caterpillars that like nothing better than to eat the plant.
So N. attenuata strikes back in a novel way, according to scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany. As they describe in Current Biology, it shifts the time of its flowering to mornings and attracts a different pollinator, a hummingbird. (NYT Science, Plant switches pollinators when caterpillars strike)
Whiteflies sabotage plant alarm systems
When spider mites attack a bean plant, the plant responds by producing odours which attract predatory mites. These predatory mites then exterminate the spider mite population, thus acting as a type of ‘bodyguard’ for the plant. However, if the plant is simultaneously attacked by whiteflies, insects that are related to aphids, the plant becomes less attractive to the predatory mites and therefore more vulnerable to spider mites.
The research team studied the strength of the plant’s “cry for help” through a chemical analysis of the plant odour blend and found that one of the odour components (beta-ocimene) is produced in much lower quantities if the plant is not only attacked by spider mites, but also by whiteflies. The production of the odour decreases because of a lower expression rate of the plant gene that codes for a crucial enzyme in the production chain. When the researchers added ocimene to the odour of plants which were attacked by both species, the attraction of predatory mites was restored.
This recent breakthrough demonstrates that there are also herbivores that can interfere with a plant’s “cry for help”, possibly because the whiteflies attempt to interfere with the plant’s defence system. Spider mites also produce more offspring on a plant under attack by whiteflies. For a spider mite, there are therefore two reasons why a bean plant which is being attacked by whiteflies is better than a bean plant that is not being attacked: more offspring and fewer bodyguards. It is therefore no surprise that the researchers found that the spider mite preferred plants infested with whiteflies above plants without them.
Read more Whiteflies sabotage alarm system of plants in distress
More information:
Whiteflies interfere with indirect plant defense against spider mites in Lima bean
Leaf cutter ants employ bacteria to grow fungus
No pigs or chickens yet. But the vast farms where leaf-cutter ants raise their fungal crops may harbor a crew of previously overlooked farmhands — nitrogen-fixing bacteria.
At least eight species of leaf-cutter ants typically live with bacteria that capture nitrogen from the air and turn it into a form that living organisms can use, says microbial ecologist Adrián Pinto-Tomás of the University of Costa Rica in San José. He and his colleagues propose that these bacterial helpers might explain how the ants feed up to 8 million workers in a single colony just by harvesting bits of nitrogen-poor leaves and letting a fungus grow on them.
Neither the fungus nor the ants, nor any other multicellular organisms, can use the atmosphere’s abundant nitrogen directly. Pinto-Tomás and his colleagues tracked the path of nitrogen through ant nests and tested inhabitants for genes active in capturing the nutrient from the air. Live-in bacteria, particularly in the genus Klebsiella, could provide an estimated 45 to 60 percent of the nitrogen in the ants’ food, the researchers report in the Nov. 20 Science.
read more . . . Classic view of leaf-cutter ants overlooked nitrogen fixing partner
More information:
Symbiotic nitrogen fixation in the fungus gardens of leaf cutter ants ( paper is here for purchase )
Farmer ants fertilize their gardens with bacteria
Video leaf cutter ants
