The avoidance of conspecific cues during egg-laying decision-making in the Asian long-horned beetle <i>Anoplophora glabripennis</i>

For insects whose larvae are incapable of moving between food resources, the selection of oviposition sites by females is critical to the survival and development of their offspring. In such insects, it is known that females utilise and benefit from conspecific cues for oviposition choice. Studying how information from the behaviour of conspecifics affects egg-laying decision-making is crucial for understanding the biology of insects, which can lead to novel strategies for pest management. We focused on the reproductive behaviour of the Asian long-horned beetle <i>Anoplophora glabripennis</i>, which has become an invasive pest species throughout the world. Here, we show that <i>A. glabripennis</i> avoids sites already containing conspecific cues during egg-laying decision-making. The field survey measuring the distance between neighbouring oviposition scars (in this species, females make scars through the bark of host branches for laying eggs) suggested that the selection of oviposition sites by females is not random. In laboratory oviposition-choice bioassays, females made less oviposition scars on branches containing scars made by other females than those without scars. In addition, female oviposition was also deterred by the presence of their own oviposition scars. Our results indicate that avoiding sites containing conspecific (and their own) traces realises fitness benefit such as reducing resource competition among larvae. This study provides insights into the reproductive behaviour of this invasive longhorn beetle, which is useful for developing environmentally friendly control methods such as oviposition deterrents.