“Busy nights: high seed dispersal by crickets in a Neotropical forest”

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Flávia Delgado Santana, Fabrício Begattio Baccaro, and Flávia Regina Capellotto Costa

Crickets dispersed an equivalent number of seeds and tended to disperse larger seeds further compared with ants

Beyond being great night singers, crickets are also seed dispersers

Phalangopsis sp. and seed of Goeppertia altissima
(Credit: Flávia Santana)

A large proportion of seed dispersal in tropical forests is performed by iconic vertebrates such as birds, bats, monkeys, and rodents. But in the daytime silence of the forest floor, humble ants also do this job—and do it quite well. Their status as the major invertebrate dispersers had not been challenged until today. But a recent study conducted in central Amazonia by researchers of the Brazilian National Institute of Amazonian Research has shown that in the busy forest nights, crickets do more than sing: they also search for and carry seeds. They are attracted by the same type of seeds favored by ants: arillate seeds, meaning seeds with an attached fleshy part that is consumed by the animal without damaging the seed. Surprisingly, crickets carry as many seeds as ants and eat only the fleshy part, acting therefore as dispersers and not as predators.

Hygronemobius sp. with Ischnosiphon arouma seeds.
(Credit: Flávia Santana)

Now one may ask: if crickets are such conspicuous dispersers, why didn’t people know this before? This is because most studies of seed dispersal are conducted during the day, but crickets prefer “night fever.” The study has also shown that crickets are generally “lazier,” not carrying seeds as far from the mother plant as ants do, but they can carry larger seeds farther, perhaps because larger seeds are too big for ants. A potential consequence of dispersal by crickets is to reduce the aggregation of newly born seedlings around the ant nest, which is the destination of seeds carried by ants. Aggregated seedlings can suffer higher mortality due do the easy of spread of diseases, so reduced aggregation may increase survival. On the other hand, ant nests are considered “safe sites,” providing better conditions for seed germination, and thus crickets could instead decrease the chances for the plant to get established. These consequences were not evaluated in this study and constitute new questions for seed ecology research. This is only one of numerous questions that this study prompts: Are nights busy with dispersal by crickets everywhere? Are all crickets able to disperse seeds? Which plants species are more dependent on dispersal by crickets? What attracts crickets to arillate seeds in particular? Read the Article