Florida News Times (EUA)

Caterpillar mimics leaves or rewards ant protection

Publicado em 09 dezembro 2020

For caterpillars that live surrounded by ants, there are two ways to avoid attacks. Be unnoticed or offer ants a sweet treat in exchange for protection. This is the main conclusion of a study funded and published by FAPESP (Sao Paulo Research Foundation). Eco-entomology..

Based on chemical analysis of interacting plants, worms, and ants, Brazilian researchers at the Federal University of Rio Grande do Sul (UFRGS) and the University of Campinas (UNICAMP) found that some worms are chemically very similar. I found that I was doing it. Feed them alive, which helps them hide from ants. However, there are chemically different species that have developed coexistence strategies through the generation of ant calorie rewards.

“Ant preys on many plant-dwelling insects and establishes a commensal interaction that benefits both ants and plants. To live in plants with ants, ants can coexist with ants. Develop a strategy. Living near ants has many advantages. Many ants are aggressive and limit the emergence of certain organisms. Therefore, near ants without being attacked by ants. If you can live in, you may have adaptive benefits, “said Lucas Augusto Kaminski, a researcher and principal of the UFRGS zoology department. Investigator for research.

He was part of a study with a scholarship from FAPESP and José Roberto Trigo, a professor at the institute who died in 2017 and was supported by FAPESP, during a postdoctoral internship at UNICAMP’s Institute of Biology. The we. The first author of this article is Luan Dias Lima, who performed other parts of the study while studying for a PhD at UFRGS.

Evolutionary pressure

In the 2000s, Trigo published a scientific paper showing how cuticle hydrocarbons (CHCs) receive selective pressure from ants. CHC covers almost all insect and plant cuticles (outermost layer) and acts as a waterproofing agent and communication signal. Ants have limited vision and chemically perceive the world through their antennae and antennae. Some insects, such as larvae and leafhoppers, have evolved to exhibit the same CHC as the inhabiting plants, and ants do not recognize them as different from plants and unknowingly protect them from attackers. I will. This type of relationship can be categorized as commensal. It is beneficial for caterpillars and neutral for ants.

In the latest study, researchers used mass spectrometry and gas chromatography to compare the CHC composition of six caterpillar species, three plant species, and two ant species. All caterpillars were myrmecophilous (“love ants”).

The results of the analysis showed approximately 95% similarity between caterpillars and plant CHCs in most cases, with no similarity to ant CHCs. The conclusion had to be that chemical camouflage was involved. This was as the researchers expected. However, in some cases, the similarity is much lower, from 34% to 55%, and the caterpillars involved need to be completely “visible” to the ants.

“This information was clearly not available anywhere,” Kaminsky said. Researchers have now gained insight: what if the very prominence of these species was an evolutionary advantage? Then they noticed another difference.

Some caterpillars are known to have dedicated organs to interact with ants, such as structures that generate substrate vibrations and fine bristles (bristle) used in chemical communications. Other important organs include glands that produce sweet fluids as a calorie reward for ants.

In camouflaged species, this “nectar” production was low or the glands were inactive. In prominent species, these organs were well-developed and produced significant amounts of fluid.

“If the caterpillars are hiding, you don’t need to give them anything, but if you want to generate rewards, you need to stand out. What’s involved here is the evolution of communication between caterpillars and ants,” Barbosa said. Mr. says.

According to the authors, these properties can lead to more and more chemically similar species with nectar-producing glands. This phenomenon is known as mimicry and is common among insects.

For example, being similar to toxic or rewarding species can be an adaptive benefit. Researchers are now proposing that a kind of reward-based imitation can also occur from a chemical point of view.

Caterpillar Chemical turns ants into bodyguards

For more information:
Luan Dias Lima et al, Chemical convergence between the guild of thermophilic caterpillars and the host plant, Eco-entomology (2020). DOI: 10.1111 / een.12941
Quote: Caterpillars, obtained from on December 9, 2020, to imitate leaves or reward ant protection It will be provided (December 9, 2020).

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Caterpillar mimics leaves or rewards ant protection

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