This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A research team led by professor Zhang Yuanming from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences has revealed that the outcomes of desert plant-herbivore interactions are strongly context-dependent. The paper is published in the journal Plant, Cell & Environment.
Plant-herbivore interactions are typically antagonistic: herbivores damage plant tissues, often reducing plant growth and reproduction. But plants do not always suffer from herbivory. Their responses can range from undercompensation to exact compensation, in which attacked plants eventually recover to levels similar to those of unattacked plants, and on to overcompensation, in which attacked plants show higher growth or reproduction.
For desert ephemerals, which have a short growing period and concentrate resource use in the spring moisture pulse, it remains unclear how often these less typical responses occur in the field and what they mean for the plants' ecological performance. To address this question, the researchers conducted a comparative study of naturally infested and uninfested plants of the annual desert ephemeral Strigosella scorpioides and its stem-boring weevil Lixus ochraceus in the Gurbantunggut Desert. The researchers tagged plants before visible weevil oviposition scars appeared, then compared growth and reproductive traits at different developmental stages.
They also carried out phytochemical analysis, Y-tube olfactometer assays and seed germination tests to examine how plant-insect interactions affect the plants and insects under low-intensity herbivory. At the first sampling stage after weevil oviposition, no significant differences were detected between naturally infested and uninfested plants in the morphological and biomass traits measured. At later developmental stages, however, differences in growth and reproduction gradually emerged.
At peak growth, the total biomass of naturally infested plants was about 2.2 times that of uninfested plants, and their fruit number was about 2.1 times higher. This stage-dependent pattern suggests that, under a low herbivore load (usually only one weevil developing per plant), weevil occupancy can coexist with higher late-stage growth and reproduction of the host plant, consistent with overcompensation. The researchers also found clear differences in the chemical profiles of naturally infested and uninfested plants.
Naturally infested plants had lower concentrations of the three glucosinolates detected and a lower relative abundance of benzyl isothiocyanate (BITC) among the volatiles. By contrast, they had higher benzaldehyde content in their tissues and a higher relative abundance of benzaldehyde among the volatiles. Y-tube olfactometer assays showed that female weevils' orientation responses to the two candidate volatiles depended strongly on their concentrations.
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