Bureau of Methods Development &
Biological Control

The root weevil Diaprepes abbreviatus (L.) is one of Florida's most serious pests of citrus and ornamental plants. The weevil was first detected in Florida during 1964 in an Apopka citrus nursery and detected again in the Apopka vicinity during 1968. An eradication effort was initiated immediately by State and Federal regulatory agencies, but the effort failed (Woodruff 1968). Currently 20 counties in Florida are known to be infested with D. abbreviatus (Fig. 1), and economic losses caused by this pest amount to more than $75 million annually to the citrus and ornamental industries (Lapointe et al. 1999).

Adult female D. abbreviatus (Fig. 2) deposit eggs (Fig. 3) with an adhesive between two juxtaposing leaves. Eggs hatch within 5-6 days, after which neonate larvae fall to the ground, dig into the soil and begin feeding on roots. The larval stage can be completed within 4 to 7 months. In citrus, larval feeding on roots can kill both seedling and mature trees. Pupation takes place in the soil and can be completed in as little as a month. Adults emerge from the soil and feed on tender citrus leaves (Browning et al. 1995). The entire life cycle can be completed in 7 to 12 months.

A biological control project for D. abbreviatus was initiated in 1969 by introducing Q. haitiensis collected from Puerto Rico. Over 86,000 adult Q. haitiensis reared in a laboratory in Apopka were released during a 4-month period from July-November, 1969, primarily in the Indian River citrus area. Surveys after these releases showed that Q. haitiensis did not establish in Florida (Sutton et al. 1972, Hall et al. 2001).

D. abbreviatus is subject to at least moderate levels of parasitism by egg parasitoids such as Q. haitiensis in Puerto Rico and other Caribbean and West Indian areas, although the economic benefits of these parasitoids are not known (Hall et al. 2001). However, because biological control by egg parasitoids holds some promise as an IPM tactic for D. abbreviatus and because previous attempts to establish Q. haitiensis in Florida failed, we elected to re-introduce Q. haitiensis into Florida. We speculated a higher probability of success in establishing the parasitoid in the more southern areas of Florida.

Reported here is an overview of the procedures we used to rear Q. haitiensis, numbers reared and released, release locations and establishment information.

Source of Q. haitiensis
The parasitoid was collected by Dr. R. Franqui, University of Puerto Rico, in Isabela, Puerto Rico, and sent to a quarantine laboratory at the Division of Plant Industry, Gainesville, Florida, on August 11, 1998. Rearing methods and field releases of the parasite were started during November 1998.

Obtaining eggs of Diaprepes abbreviatus for rearing the parasitoid
About 150 adults of D. abbreviatus were reared in an aluminum screened cage (30x50x55cm)(Fig. 4). The cage was covered by a piece of saran wrap to keep the humidity in the cage about 70-80%. The weevils were fed with a bouquet of tender citrus leaves and green bean pods. The bouquet of citrus was changed twice a week. The cage was housed in a room at 82°F, 14L:10D. Every afternoon, 12 oviposition substrates were hung in each cage to obtain D. abbreviatus eggs. Each oviposition substrate consisted of one piece of wax paper and one piece of stretched parafilm, equal in size (2x25 cm), stapled together. Weevils oviposited egg masses (Fig. 5 & 6) between the two layers of this substrate. We use the phrase ‘egg strip’ to refer to one of these oviposition substrates containing eggs.

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Fig. 1. Distribution of D. abbreviatus and Q. haitiensis in Florida.

Fig 2. Adult female D. abbreviatus

Fig 3. Eggs

Fig 4. Diaprepes Rearing Cage

Fig 5. Diaprepes Egg Strip

Fig 6. Diaprepes Egg Strips

Fig 7. Separated Egg Strip

Fig 8. Desiccator

Fig 9. Q. haitiensis adult

Fig 10. Adult parasite box