Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
RESEARCH ADMINISTRATION
Non Technical Summary
The range expansion of Diaprepes abbreviatus into new areas continues to challenge agricultural and landscape plant health and survival. This project seeks to evolve and integrate complementary approaches to limit the extent of spread and injury due to this new insect in the U.S.
Animal Health Component
70%
Research Effort Categories
Basic
20%
Applied
70%
Developmental
10%
Goals / Objectives
Research continues in the effort to find solutions to the Diaprepes problem in Florida. Research funded in this program has focused on biology, ecology, host plant relations ad injury mad various strategies to suppress populations of the weevil and to minimize the negative impact on commercially available plants. Finding solutions will require innovative research in many areas including biological control, chemical control, monitoring methods and plant resistance. Solutions to the Diaprepes problem must be environmentally safe, cost effective, and compatible with other aspects of growing operations, which increases the complexity of finding solutions. In view of the literature review discussed below, the Diaprepes Task Force earlier identified the following as areas in which research is needed in order to develop and integrate control strategies for Diaprepes. These areas of research can be summarized in four general objective areas that will be the basis for research
conducted under this continuing special grant. These objective areas have been recently reviewed by the task force and remain as the key areas for research. They are: 1. To further characterize the developmental and reproductive biology, population dynamics, and seasonal phenology of Diaprepes abbreviatus; 2. To define interactions between Diaprepes and citrus, vegetables, and ornamental plants that are hosts, to characterize damage to these plants and to develop monitoring and sampling methods; 3. To develop and evaluate individual strategies to suppress populations of Diaprepes on susceptible plants, including cultural, chemical, biological and host plant resistance; and 4. To evaluate integration of suppression strategies and their impact on reduction of damage due to Diaprepes infestations on crops of importance to Florida and beyond.
Project Methods
There is an obvious need to implement a decision support system for Diaprepes with emphasis on detection, threshold-based remedial actions, and a mix of suppression strategies including the judicious use of pesticides when necessary. Our overall goal is to stabilize pest populations below economically damaging levels thereby preventing further spread while minimizing the impact on the environment. Quantitative sampling methods are vital to the development of a decision support system for Diaprepes based on biological models that emphasize threshold based remedial actions. No methods exist to directly assess larval populations in soil unless destruction of the whole tree is an accepted option. This procedure is labor intensive and lacks grower friendliness but must be done to generate reliable biological data on larval development in relationship to root injury. Unbaited Tedders traps can be effective devices for estimating the seasonal abundance of adults emerging from
the soil beneath the tree. This monitoring method lacks efficiency and cannot be employed as an early detection device for adults entering a citrus planting for the first time. However, the Tedders trap has potential as a scouting tool that can be exploited for the development of biological models basic to a decision support system for Diaprepes. In addition, biological data collected from citrus and alternate host plants found in association with citrus (e.g., Panicum, Sesbania) is limited. Seasonal data on: 1) adult emergence from soil 2) adult life expectancy in the field, 3) female ovipositional behavior and length of ovipositional cycle, 4) time and duration of neonate invasion into the soil and 5) rate of larval, pupal and adult development in the soil is desperately needed to develop models and define threshold-based remedial actions and suppressive strategies for control of key developmental life stages. A wide range of parasites, predators and pathogens attack Diaprepes at
one or more developmental stages within the tree canopy or in the soil. Independent reports suggest that ants are important predators of eggs, larvae and adults, but no research has focused on the relative impact of different naturally-occurring ant species on these life stages. Since ant species show varying propensities for foraging in the tree, on the soil surface, and underground, it is likely that the different life stages of Diaprepes have different ant predators. Previous research with entomopathogenic fungi and nematodes suggest seasonality among naturally-occurring pathogens that might relate to host density and environmental conditions. It is crucial to IPM strategies of the future, that the role of native natural enemies of the various life stages of Diaprepes is better defined. Foliar applications of pesticides to control adult Diaprepes, and soil-applied pesticides and entomopathogenic nematodes aid fungi to control larvae, have been tried with little success. Because
adults of the weevil can emerge year-round and are long-lived, eggs can be laid over extended periods of time.