Among the more than 6000 known thrips species, about 300 have a curious habit: through feeding, these thrips can induce modifications in the plant tissue, creating a structure named gall. Galls can be in a variety of forms, such as leaf rolls or folds, “pouch-like” structures, rosettes, and others. These galls share two traits: a partially or fully enclosed chamber, where the thrips live; and thickened plant tissue that serves as food to these insects.

Thrips are not the only living beings able to create galls. A variety of other beings, from insects like some dipterans and hymenopterans, to some bacteria and fungi, can induce galls in plant tissue. However, thrips are different from other galling insects, by creating galls through their feeding. Thrips can also have multiple individuals sharing the same gall. There are records of galls with thousands of thrips living inside it!

But what is the advantage of living within these structures? Like a house that protects its owners from rainfall, wind and other environmental conditions, galls protect the thrips living in it. Inside the gall there are no rain, strong winds, too much light, predators, and other things that negatively impact the development and survival of thrips. Thus, they are able to spend less time and energy searching a favorable environment or fleeing from predators, and may invest more in feeding or reproducing.

The images show some galls induced by species of Holopothrips, the main group of galling thrips in the New World!

Reference: Lindner, M.F.; Ferrari, A.; Mound, L.A. & Cavalleri, A. (2018) Holopothrips diversity—a Neotropical genus of gall-inducing insects (Thysanoptera, Phlaeothripidae). Zootaxa 4494(1):1–99.

Holopothrips infestans galls in Acca sellowiana

Holopothrips acrioris gall in Myrcia selloi

Holopothrips flavisetis galls in Myrtaceae

Holopothrips molzi gall in Myrcia guianensis

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This post was originally created for the fan pages of Laboratório de Entomologia Sistemática (LES) from Universidade Federal do Rio Grande do Sul (UFRGS). Reposted here with permission from the authors.

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