Fecundity and Fertility of Rhynchophorus cruentatus (Coleoptera: Curculionidae)

The palmetto weevil (R. cruentatus F.) breeds in a variety of stressed or dying palms (Giblin-Davis & Howard 1988, 1989). These large (1.9 3.0 cm long) weevils are associated with the native cabbage palmetto, Sabal palmetto (Walter), in Florida (Woodruff 1967). Semiochemicals emanating from stressed or dying palms and male conspecifics (Weissling et al. 1992, 1993, 1994, Giblin-Davis et al. 1994) are attractive to R. cruentatus adults. Although not fully understood, mating apparently takes place on dying palms and females lay their eggs in the leaf bases or directly into the wounds of the host. Larvae develop primarily in the crown region but can occasionally be found in the stem tissue. Last instar larvae migrate to the fibrous stem periphery or petiolar bases and construct cocoons from fiber (Giblin-Davis & Howard 1988). Research on an improved method to culture R. cruentatus has required the collection of a large number of eggs to produce neonate larvae for evaluation of diets. Using pineapple, Anana comosus (L.), as an ovipositional substrate, Giblin-Davis et al. (1989) reported the mean lifetime fecundity of field-collected females as 26 ? 15 eggs per female. However, pineapple proved to be a difficult media to dissect for removal of eggs. More suitable ovipositional substrates were investigated and we found that apple (Pyrus malus L.) slices were easily dissected and were readily accepted by R. cruentatus females. Using apple slices, we reinvestigated the fecundity of R. cruentatus females and determined fertility. Cocoons were harvested in the field from infested palms or in the laboratory from sugarcane (Saccharum officinarum L.) stem (Giblin-Davis et al. 1989). Cocoons were placed individually in covered 100-ml plastic cups with moistened tissue paper (Giblin-Davis et al. 1989) and were stored at 29?C until adult emergence. One male and one female were placed in a 500-ml covered plastic container with moistened tissue. After 48-72 h, males were removed and a slice of apple ('Red Delicious') was added. Slices were thin (5-15 mm; 10-18 g wet weight), convex segments covered by peel. Females oviposit through the apple pulp and most eggs are found along the peel. All containers were placed in an environmental chamber at 290 C with a 13:11 (L:D) photoperiod. Apple slices were usually replaced every 1-3 days until female death. Slices removed from containers were carefully dissected and eggs were removed. This test was repeated five times with four or five females per test (22 females total). Data were converted to the number of eggs laid per female per week. In addition, the total number of eggs laid per female was determined. During two of the tests, eggs removed from apple slices were placed in 15 x 100 mm plastic petri dishes lined with watermoistened filter paper, sealed with parafilm, and placed in the environmental chamber. Neonate larvae were removed from each dish at daily intervals and the dish resealed until all eggs hatched or decomposed. For the first test, fertility was determined every one to three days for 45 d. During the second test, eggs were col