A survey of scale insects (Hemiptera, Coccoidea) on avocados, olives, and grapes in the Peruvian region of Arequipa.

Scale insects (Hemiptera, Coccoidea) are among the most economically important plant pests known throughout the world. They are found frequently on the leaves, stems, roots, and fruit, and are of great concern to importers of these plant products due to their great potential to become invasive species in their new environment when separated from their natural enemies. In Peru, knowledge of scale insects is limited to a few economically important species primarily because local, regional, or national surveys have not been conducted. This study aimed to document and update knowledge of scale insect diversity on avocado, olive, and grape plantations in the Arequipa region of Peru. Samples were collected from fruit orchards in June 2019, February-March 2020, August 2021, and July 2022. Sampling was performed in 35 localities across eight provinces in the Arequipa region where crops are grown for commercial purposes. Leaves, branches, and fruit of each of these three crops at each locality were randomly sampled, and inspected for the presence of scale insects. A total of 13,991 scale insect specimens were collected from 668 samples. Diversity indices were used to assess the structure of the scale insect communities across the three crops. Five families, 22 genera, and 33 species were identified. Species in the family Diaspididae were the most abundant, followed by Coccidae, Pseudococcidae, Ortheziidae and Eriococcidae, respectively. Twenty-eight species of scale insects are reported for the first time in the Arequipa region, nine of which are new records for Peru. The highest species richness was found on grapes, followed by avocados, and the lowest richness was found in olives. A dichotomous morphological key to the species of scale insects reported in this study is provided.