Bureau of Methods Development &
Biological Control

Diaprepes abbreviatus was first found in Apopka, Florida in 1964. It is a destructive pest that has spread throughout the citrus areas of the state. While the adults feed and lay eggs on the citrus leaves, it is the larvae that kill the tree by destroying the roots and girdling the crown area. Additional commercial crops such as sugarcane, ornamentals, yucca, papaya, sweet potatoes, cotton and peppers are affected by this pest. The host list features approximately 450 different species that support the Diaprepes life cycle. The large host list and long life cycle creates pressure in Florida’s agricultural community to gain control of this pest.

Laboratory and field research is being conducted by universities, government agencies and private companies to develop effective chemical and biological controls of the various stages of this weevil. Other studies include efforts to improve present methods for surveillance and detection techniques for nurseries and citrus groves, field studies on adult weevil dispersal, trap efficiency, adult weevil longevity and reproductive biology and seasonal larval populations. Many insect stages from egg to adult are needed to conduct these studies and the life cycle is extremely slow and unpredictable. Field collected insects are not always available in the quantities needed. With the assistance of the USDA in Ft. Pierce, an additional colony of weevils was started at DPI in February 2000 to increase the supply of research material.

The Diaprepes life cycle is highly variable in the facility as it is in nature. The entire life cycle, from egg to adult, averages between 120-190 days and longer. Because of this variability, rearing in the laboratory is extremely labor-intensive. The grubs, pupae and adults are handled individually during transfer to fresh diet or sorting.

Small plexiglas cages with 30-50 pairs of adults each are maintained for egg production. Each cage is cleaned twice weekly and held for 3 months. The adults are fed organic carrots, larval diet and citrus leaves raised from seed. Organic green beans can be used when available, as well as silver buttonwood leaves. Fresh food and water is placed in each cage at the time of egg collection.

Pairs of 1-inch strips of wax paper are taped to the inside of the cage for egg laying. The female weevil lays egg clutches of various sizes, gluing them between the 2 wax paper strips. The strips are collected daily and held in Ziploc bags, equipped with a moistened dental wick, to incubate for one week. The newly hatched neonates are ready to be placed on an artificial diet, but can survive for up to 7 days without food.