Notes on the Avocado Psyllids

Background. Avocado (Persea americana) is a plant that probably needs no introduction. The plant is grown around the world and everybody loves avocados! Probably less loved, however, are the creatures responsible for doing this to avocado leaves:

image credit: © José Humberto Castañón González, some rights reserved (CC-BY-NC)

If you have an avocado tree growing in your backyard or somewhere else in your neighborhood, you've probably never seen these leaf galls. Unless you happen to live in Mexico, where Trioza anceps - the psyllid responsible for these galls - is the most frequently observed native Mexican psyllid on iNaturalist.

As of now, the psyllid is not known to be established in the USA or elsewhere outside of its native range in Mexico/Guatemala, where it is quite common. For a plant that has been imported around the world, it is unusual that one of its primary parasites has not yet been inadvertently introduced as well, as has happened with so many other plants (the Asian citrus psyllid comes to mind), though it may just be a matter of time. But while Trioza anceps is common in Mexico, it does not seem to be present in other parts of Persea americana's native range such as South America, which may indicate that the psyllid is very narrowly host specific to only the Mexican/Guatemalan race/subspecies of Avocados.

Species. Trioza anceps is the most commonly observed avocado psyllid due to to the conspicuous nature of its galls, but it is actually just one of at least four species of Trioza on Avocado. All appear to have fairly narrow natural distributions, again indicating that species may have a preference for specific races/subspecies of avocados. The four psyllid species are outlined below.

1. Trioza anceps. Creates leaf galls projecting on the upper surface of the leaves, as pictured above. Mexico/Guatemala
2. Trioza perseae. Similar to Trioza anceps, but leaf galls project from the ventral surface of the leaf. Peru/Columbia. Tuthill notes that this species only effected indigenous South American avocados not the Mexican/Guatemalan variety, even though some of the foliage intermingled. I could not find any evidence of this species on iNaturalist in South American Persea americana observations.
3. Trioza godoyae. This species does not create leaf galls like the previously mentioned species but instead creates marginal leaf roll galls, similar to those created by the Red Bay Psyllid (Trioza magnoliae) on Persea palustris. Known only from Costa Rica. While these galls should be conspicuous, there are no examples of this species yet on iNaturalist.
4. Trioza aguacate. Adults are similar to Trioza anceps, but nymphs do not induce leaf galls. Instead, they cause the deformation of leaves and young shoots. Known only from Mexico, apparently sympatric with Trioza anceps.

Publicado el junio 21, 2022 12:21 TARDE por psyllidhipster psyllidhipster


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