First Report of Caryobruchus gleditsiae (Coleoptera: Chrysomelidae) on Brahea berlandieri in Northeast Mexico

Herein, we report the first occurrence of the palm seed weevil, Caryobruchus gleditsiae Johansson & L. (Coleoptera: Chrysomelidae), from the seeds of the palm, Brahea berlandieri Bartlett (Arecaceae) in northeastern Mexico. Our discovery was serendipitous in that our objective in collecting B. berlandieri fruits was to create a germplasm bank of different palm species from the state of Tamaulipas, Mexico (Reyes-Zepeda, 2016, Final Technical Report of Project: Manejo y conservación del germoplasma de tres especies de palma de interés comercial en el estado de Tamaulipas, México. Registry: UAT-PTC-186. PRODEP-SEP. México. http://dx.doi.org/10.13140/RG.2.2.31107.84002, accessed 10 April 2020.).

In October 2016, we collected 30 fruits from B. berlandieri trees growing at 10 locations in the state (Table 1). Collected fruits were sealed in plastic zipper bags, placed in a cooler at 5 ± 2°C, and transported to the Population Ecology Laboratory, Applied Ecology Institute, Autonomous University of Tamaulipas. There, ripe fruits were washed with tap water and placed on a sieve (1.0 × 1.0 × 0.05 m) inside of an entomologic cage (1.8 × 1.8 × 1.8 m), where they remained under field conditions for approximately 25 d. Then, the exocarp and mesocarp were manually removed from the seeds, and seeds were subsequently washed with tap water and dried at room temperature. Once dried, the seeds were placed in properly labeled plastic bottles with an airtight lid and stored in the laboratory. In January 2017, bruchids were observed inside the plastic bottles (Fig. 1A). These had emerged from the palm seeds (Fig. 1B) from a round exit hole. A specimen was identified as C. gleditsiae (Fig. 1A) using the taxonomic keys of Nilsson and Johnson (1990, Coleop. Bull. 44: 50–59; 1993, Mem. Am. Entomol. Soc. 41: 1–104).

Table 1 Location of B. berlandieri plants and number of C. gleditsiae emerged.

View Fullscreen

View Figure

• Download as Powerpoint
• Download Figure

The length of C. gleditsiae ranged from 0.74 to 0.84 cm, possibly the size of the seed (7.8–9.2 mm; Fig. 1C). Nilsson and Johnson (1993) reported that the length of C. gleditsiae ranges from 7.2 to 12.1 mm in males and 4.3 to 11.0 mm in females. Woodruff (1968, Florida Dept. Agric. Entomol. Circ. 73: 1–21968) mentioned that the size of C. gleditsiae partially depends on the size of the host seed.

Caryobruchus gleditsiae is reported from the Antilles, Bahamas, Bermuda, Cuba, Dominican Republic, El Salvador, Guatemala, Honduras, Jamaica, Panama, Spain (Tenerife), and the southeastern United States. In Mexico, it is reported from Campeche, Chiapas, Guerrero, Hidalgo, Michoacan, Nayarit, Oaxaca, Puebla, San Luis Potosí, Sinaloa, Sonora, Tamaulipas, and Veracruz (White, 1983, The Peterson Field Guide Series No. 29. Houghton Mifflin Co., Boston, MA; Nilsson and Johnson 1990; Romero and Johnson, 2004, Coleop. Bull. 58: 613–635; Yus-Ramos, 2019, Boln. Asoc. Esp. Ent. 43: 229–259). Its main hosts are species of Sabal, but it also has been reported from species of Chamaedorea, Coccothrinax, Copernicia, Litona, Phoenix, Serenoa, Thrinax, Washingtonia, and Yucca (Nilsson and Johnson 1990, 1993; Johnson et al., 1995, Principes 39: 25–35; Johnson and Romero, 2004, Rev. Bras. Entomol. 48: 401–408; Fernández and González, 2015, Rev. Colombiana Cienc. Anim. 7: 120–129). Adults feed on pollen and nectar from their hosts. The female lays one egg on the outer surface of a seed. Upon hatching, the larva pierces the seed coat and enters the seed. Inside the seed, the bruchid develops through three larval stages and the pupa. Upon emergence from pupation, the adult creates a round hole to exit the seed (Woodruff 1968; White 1983; Johnson et al. 1995).

We observed one to two adult C. gleditsiae emerged from the collections of 30 seeds each of B. berlandieri (Table 1). Emergence from these seeds indicates that the female oviposited on the seed while it was in fruit on the plant. The state of fruit maturity when the female oviposited on the fruit is unknown; however, Johnson and Romero (2004) grouped bruchids into three guilds according to their oviposition behavior: (1) those that oviposit only on the walls of the fruit; (2) those that oviposit only on mature seeds while the fruit is on the plant; and (3) those that oviposit only on mature seeds that are in the ground. They placed C. gleditsiae in their third guild, which is contrary to our observations in that the bruchids emerged from seed that was within ripe fruits collected from the plant. We also observed that, inside the plastic bottles, the seeds had one egg per seed, with a total of up to 139 seeds on which oviposition had occurred; yet, no eggs hatched (Fig. 1D). Johnson and Romero (2004) also reported that C. gleditsiae females lay only one egg per seed in Sabal species. Although the number of bruchids that emerged is not significant (one to two bruchids in 30 seeds per B. berlandieri population), more studies are needed to learn the details of their feeding habits, oviposition behavior, and host plant associations to better understand palm seed weevil.

The palm, B. berlandieri, is endemic to the Sierra Madre Oriental. It is found in the states of Coahuila, Nuevo Leon, Tamaulipas, San Luis Potosi, Guanajuato, Queretaro, and Hidalgo (Quero, 2004, Palmae, Pp. 1–23. In Rzedowski, J., and Calderon-de-Rzedowski, G. (eds.), Flora del Bajío y de Regiones Adyacentes, Fascículo 129. Instituto de Ecología, Veracruz, Mexico). Its palm leaves are used to create handicrafts such as hats, baskets, and fans (Quero, 1992, Principes 36: 203–216). It is listed in NOM-059-SEMARNAT-2010 (Norma Oficial Mexicana-Secretaría de Medio Ambiente y Recursos Naturales) under the risk category “Subject to Special Protection” (Pr), which indicates that it may be threatened by factors that negatively affect its viability (NOM-059-SEMARNAT-2010 (Norma Oficial Mexicana-Secretaría de Medio Ambiente y Recursos Naturales)). 2020. NORMA Oficial Mexicana NOM-059-SEMARNAT-2010, Protección ambiental-Especies nativas de México de flora y fauna silvestres-Categorías de riesgo y especificaciones para su inclusión, exclusión o cambio-Lista de especies en riesgo. http://dof.gob.mx/nota_detalle_popup.php?codigo=5173091, accessed 10 April 2020). In this norm are the flora and wild fauna, terrestrial and aquatic, in danger of extinction and threatened and those subject to special protection in Mexico. Very few herbivores have been reported from B. berlandier. One is Pterophylla beltrani Bolivar and Bolivar (Orthoptera: Tettigoniidae), which feeds on palm foliage (Marez-López, 2020, Southwest. Entomol. 45: 209–216). Ours is the first report of C. gleditsiae adults emerging from B. berlandieri seeds in northeastern Mexico.