Texto para as questões de 79 a 81
During the nineteen-seventies and eighties, a researcher at the University of Washington started noticing something strange in the college’s experimental forest. For years, a blight of caterpillars had been munching the trees to death. Then, suddenly, the caterpillars themselves started dying off. The forest was able to recover. But what had happened to the caterpillars?
The researcher, David Rhoades, who had a background in chemistry and zoology, found that the trees in the forest had changed the chemistry of their leaves, to the detriment of the caterpillars. Even more surprising, trees that had been nibbled by caterpillars weren’t the only ones that had changed their chemistry. Some were changing their leaves before caterpillars reached them, as if they’d received a warning. A shocking possibility presented itself: the trees were signalling to one another.
Zoë Schlanger recounts Rhoades’s story in her new book, “The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth.”
The contemporary world of botany that Schlanger explores in “The Light Eaters” is still divided over the matter of how plants sense the world and whether they can be said to communicate. But, in the past twenty years, the idea that plants communicate has gained broader acceptance. Research in recent decades has shown garden-variety lima beans protecting themselves by synthesizing and releasing chemicals to summon the predators of the insects that eat them; lab-grown pea shoots navigating mazes and responding to the sound of running water; and a chameleonic vine in the jungles of Chile mimicking the shape and color of nearby plants by a mechanism that’s not yet understood.
Schlanger acknowledges that some of the research yields as many questions as answers. It’s not clear how the vine gathers information about surrounding plants to perform its mimicry.
New Yorker. 12 June 2024. Adaptado.
Conforme o texto, a experiência conduzida por David Rhoades, na floresta experimental da Universidade de Washington, tornou-se marcante para a botânica, por revelar a
dependência das árvores de inimigos naturais para a manutenção do equilíbrio das florestas.
alteração da composição das folhas, capaz de comprometer a sobrevivência de insetos herbívoros.
variabilidade das lagartas como fator decisivo para a resiliência dos ecossistemas.
influência determinante da fertilidade do solo na recuperação da vegetação.
oscilação natural das populações de pragas como causa da regeneração florestal.
Resolução
O texto relata que as lagartas estavam devorando as árvores da floresta experimental. Depois, as próprias lagartas começaram a morrer, e a floresta conseguiu se recuperar. David Rhoades investigou o que havia provocado essa mudança.
A descoberta aparece no trecho: “the trees in the forest had changed the chemistry of their leaves, to the detriment of the caterpillars”, isto é, “as árvores da floresta haviam alterado a composição química de suas folhas, em prejuízo das lagartas”. A expressão “to the detriment of” significa “em prejuízo de”: portanto, a mudança nas folhas prejudicava as lagartas que se alimentavam delas. Como as lagartas são insetos herbívoros, isso corresponde diretamente à resposta indicada: alteração da composição das folhas capaz de comprometer a sobrevivência desses insetos.
O pesquisador também observou mudanças em árvores que ainda não tinham sido atacadas. Isso levantou a hipótese de que elas recebessem sinais de outras árvores, mas o texto apresenta essa comunicação como uma possibilidade, não como uma conclusão definitiva.