Heilipus squamosus (LeConte, 1824)

Anzaldo, Salvatore S & Diaz-Grisales, Valentina, 2022, Heilipus squamosus (LeConte, 1824): clarification of the correct name for the " avocado tree girdler " with updates on its biology and distribution (Coleoptera, Curculionidae, Molytinae, Hylobiini), Biodiversity Data Journal 10, pp. 85499-85499 : 85499

Heilipus squamosus (LeConte, 1824)

Heilipus squamosus Original combination Pissodes squamosus

Heilipus squamosus https://www.biodiversitylibrary.org/page/15913340

Heilipus squamosus https://mczbase.mcz.harvard.edu/guid/MCZ:Ent:5176

Heilipus squamosus Synonyms

Heilipus squamosus Boheman, 1836: 171 (not LeConte, 1824).

Heilipus squamosus https://www.biodiversitylibrary.org/page/4109434

Distribution

The previously-published state distribution of Heilipus squamosus is in the south-eastern United States-Georgia ( LeConte 1824), Florida ( LeConte and Horn 1876), Tennessee ( Blatchley and Leng 1916), South Carolina, Alabama and Mississippi ( Wolfenbarger 1950), North Carolina ( O'Brien and Wibmer 1982) and Virginia ( Hoffman 2003). The species was considered rare ( LeConte 1824, LeConte and Horn 1876, Barber 1912) and, apart from specimens from Florida where the species was a pest on avocado, relatively few specimens of this large and distinctive weevil have been collected and deposited in natural history collections.

In the past 20 years, citizen science initiatives (e.g. BugGuide, iNaturalist) have yielded observations of H. squamosus from all States in its previously reported range plus seven additional States, expanding the distribution of this species to the northern and western regions of the United States:

Alabama, Arkansas (new State record), Florida, Georgia, Kansas (new State record), Kentucky (new State record), Louisiana (new State record), Missouri (new State record), Mississippi, North Carolina, Oklahoma (new State record), South Carolina, Tennessee, Texas (new State record) and Virginia (Fig. 2 C).

Biology

The biology of H. squamosus is still incompletely known. Before it became a pest of non-native avocado in Florida, the published natural history information was limited to a record from "under pine bark" ( LeConte and Horn 1876: 141) and from "budding shoots of sassafras" ( Blatchley and Leng 1916: 187). The avocado industry in Florida traces back to the early 20th century, though Persea americana Mill. was first brought to and became naturalised in Florida before 1835 ( Wolfe et al. 1942). Wolfenbarger (1948) reports the earliest evidence of H. squamosus causing damage to avocado to be from the late 1930s and, by the late 1940s, the weevil became "one of the most dangerous pests of the avocado" ( Wolfe et al. 1949). Larvae feed under the bark near ground level and can girdle trees and cause an 8-10% loss of avocado trees in a grove ( Wolfenbarger 1948). The status of H. squamosus as a pest appears to have continued through the 1950s, but the species was rarely observed after ( Wolfenbarger 1971).

The native hosts for the weevil have been suspected to be other members of the Lauraceae , namely Lindera melissifolia (Walter) Blume (pondberry), Litsea aestivalis (L.) Fernald (pondspice), Persea borbonia (L.) Spreng. (redbay) and Sassafras albidum (Nutt.) Nees (sassafras), though no definitive rearing records are known. Of these species, sassafras is widely distributed throughout the eastern United States; the other three are restricted to coastal plains and swampy areas, with pondberry and pondspice being listed as a federally endangered and threatened species, respectively.

Adult weevils have been found on pondberry in North Carolina ( U.S. Fish and Wildlife Service 1993) and on pondspice in Georgia ( Cameron et al. 2008, Fraedrich et al. 2011). An unidentified weevil larva described as being a similar size to the adult H. squamosus was found causing feeding damage to the root collar at the base of a pondberry plant in South Carolina ( Fraedrich et al. 2011). Redbay was suggested as a possible host due to the weevil’s distribution along the East Coast ( Barber 1912, Hoffman 2003); Cameron et al. (2008) observed debarking damage to redbay branches which was noted to be very similar to the damage observed on pondspice branches at a locality in Georgia where H. squamosus was also found, but no more direct associations are known with redbay. Adult weevils have been collected on sassafras in Tennessee ( Blatchley and Leng 1916) and Alabama [AUMNH].

Additional records: Wolfenbarger (1948) reported specimens collected "on cotton, sassafras and Satsuma orange" and, in a subsequent paper ( Wolfenbarger 1950), he adds “camphor” to the list. Camphor, Cinnamomum camphora (L.) J. Presl, is a non-native species of Lauraceae naturalised in parts of south-eastern United States. No additional records were found indicating an association of H. squamosus . Three specimens have been collected from Isle of Wight Co., Virginia on Diospyros virginiana L. (wild persimmon; Ebenaceae ) (CMNC; Art Evans, pers. comm.). One specimen from Spotsylvania Co., Virginia was photographed "on dogbane hemp", Apocynum cannabinum L. ( Apocynaceae ) (iNaturalist, BugGuide).

Figures

Figure 2. Heilipus squamosus. Scale bars = 2 mm. A: lateral habitus. B: dorsal habitus. C: distribution map (circles = iNaturalist / BugGuide records, stars = specimen data, squares = literature records; red symbols = 20 th century records, black symbols = 21 st century records).