J. B. Beavers

Survival of Diaprepes abbreviatus larvae on selected native and ornamental Florida plants.

Of 65 ornamental nursery and 6 native plant species examined during 1976-7 at Plymouth, FL, only 9 species of nursery plants and 1 native plant species other than citrus and sugarcane appeared suitable for the development of larvae of Diaprepes abbreviatus (L.). Transport of infested ornamental plants could convey the weevil within and outside of the regulated area in south and central Florida. Native host species could contribute to local weevil populations in Florida.

Further attempts to establish the weevil egg parasite, Tetrastichus haitiensis in Florida.

In a further attempt to establish Tetrastichus haitiensis Gahan, an egg parasite of the weevil, Diaprepes abbreviatus (L.), releases of laboratory reared stock were made during 1970 and 1971 at Apopka and West Palm Beach, Florida. Recovery efforts made periodically during 1970-73 failed to provide evidence of establishment.

Development of Diaprepes Abbreviatus on Potted Citrus Seedlings

Adult Diaprepes abbreviatus (L.) were recovered from citrus seedlings 132 through 168 days after infestation of the plants with 0- to 24-hour old larvae. Pupae were recovered 98 through 238 days after infestation. The number of larval instars could not be determined from the frequency distribution curves of head capsule measurements.

Diaprepes abbreviatus response to light traps in field and cage tests.

Using electroretinogram techniques spectral sensitivity of the compound eyes of Diaprepes abbreviatus (L.) was determined as 510-550 nm with peak sensitivity at 530 nm. Cage and field tests of gravity and electrocutor light traps with a fluorescent lamp having maximum output of light in this spectral region were made to develop a survey method for this weevil. Of 4 types of traps tested, an electrocutor trap equipped with a funnel and holding chamber collected more weevils in cage and field tests than omnidirectional gravity light traps, stainless steel electrocutor traps, or tree traps. The capture efficiency of the electrocutor trap is not considered sufficient to recommend it as a survey tool for D. abbreviatus.

Two Muscardine Fungi Pathogenic to Diaprepes Abbreviatus

In the laboratory, the fungus Metarrhizium anisopliae (Metschnikoff) Sorokin infected 6.7% of the adults and none of the larvae of the so-called sugarcane rootstalk borer weevil, Diaprepres abbreviatus (L.). In contrast, Beauveria bassiana (Balsamo) Vuillemin infected 92.7% of the adults within 7 days and 76.9% of the larvae within 12 days.