Mealybug species (Hemiptera: Pseudococcidae) associated with Cacao mild mosaic virus and evidence of virus acquisition

Authors: Puig, Alina; WURZEL, SARAH; SUAREZ, STEPHANIE - MARS, INC.; MARELLI, JEAN-PHILIPPE - MARS, INC.; NIOGRET, JEROME - MARS, INC.

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2021
Publication Date: 11/4/2021
Citation: Puig, A.S., Wurzel, S.B., Suarez, S., Marelli, J., Niogret, J. 2021. Mealybug species (Hemiptera: Pseudococcidae) associated with Cacao mild mosaic virus and evidence of virus acquisition. Insects. 12(11):994. https://doi.org/10.3390/insects12110994.
DOI: https://doi.org/10.3390/insects12110994

Interpretive Summary: Cacao mild mosaic virus (CaMMV) was discovered in Trinidad in 1943, where it was shown to be transmitted by five mealybug species. It was recently detected in Puerto Rico, Brazil, and the USA; however, no information is available on insect vectors in these locations. Mealybugs belong to a diverse group known as Pseudococcidae, and species composition differs among geographic regions. A study conducted on infected trees in Florida found four species of mealybug present: Pseudococcus jackbeardsleyi, Maconellicoccus hirsutus, Pseudococcus comstocki, and Ferrisia virgata. Of these, P. jackbeardsleyi and M. hirsutus have not been tested for their ability to transmit viruses to cacao. CaMMV was detected in 34.6 to 43.1% of the insects tested, however, acquisition did not differ among species. Due to their prevalence (>72%), transmission studies should be conducted to determine the ability of P. jackbeardsleyi and M. hirsutus to transmit the virus. This research improves our understanding of the mealybugs associated with CaMMV-infected plants in Florida and identifies potential new insect vectors. Knowledge of vector species is essential for selecting the most effective control strategies and minimizing disease spread.

Technical Abstract: Theobroma cacao is affected by viruses on every continent where the crop is cultivated, with the most well-known ones belonging to the Badnavirus genus. One of these, Cacao mild mosaic virus (CaMMV), is present in the Americas, and is transmitted by several species of Pseudococcidae (mealybugs). To determine which species are associated with virus-affected cacao plants in North America, and assess their potential as vectors, mealybugs (n=166) were collected from infected trees in Florida, and identified using COI, ITS2, and 28S markers. The species present were Pseudococcus jackbeardsleyi (38%; n=63), Maconellicoccus hirsutus (34.3%; n=57), Pseudococcus comstocki (15.7%; n=26), and Ferrisia virgata (12%; n=20). Virus acquisition was assessed by testing mealybug DNA (0.8ng) using a nested PCR that amplified a 500bp fragment of the movement protein-coat protein region of CaMMV. Virus sequences were obtained from 34.6 to 43.1% of the insects tested, however, acquisition did not differ among species, X2 (3, N = 166) = 0.56, p < 0.91. This study identified two new mealybug species, P. jackbeardsleyi and M. hirsutus, as potential vectors of CaMMV. This information is essential for understanding the infection cycle of CaMMV and developing effective management strategies.