BIOLOGICAL CONTROL OF ARTHROPOD PESTS AND WEEDS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0225507
• Multistate No.: S-1034
• Project Start Date: May 1, 2011
• Project End Date: Sep 30, 2012
• Program Code: [(N/A)]- (N/A)

Recipient Organization
CLEMSON UNIVERSITY
(N/A)
CLEMSON,SC 29634

Performing Department
School of Agricultural, Forest, & Environmental Sciences

Non Technical Summary
The growing emphasis on environmental and food safety inssues has intensified interests in using biological control as a means of controlling pests. The effective use of natural enemies is dependent upon a comprehensive understanding of their ecology and that of the targets, the production practices, and the most effective means of suing them. The introduction of invasive species and the proliferation of native or naturalized species continue to make biological control relevant. There is a need to create more effective biological control techniques and integrating protection chemicals in systems that produce food, fibers, as well as ornamental crops. Insects, mites and weeds (invasive or native) continue to cause significant amount of damage and costs of control to the agriculture of the US. The oak lecanium scale is perhaps one of the most common soft scale species plaguing the oak trees in both landscape and nursery. Mealybugs are also one of the most common but difficult to control pest in many ornamental production systems. Control of these pests by means of biological control can provide benefits such as reduce the amount of pesticides used, the human, animal and environmental risks associated with pesticide applications, and economic costs of the damage and applications. Understanding the interactions between conventional and novel pest management technology and the natural enemies will lead to a more effective integration of biological control in pest management systems. The studies outlined in this project will improve our understanding of the ecology of the natural enemies and methods in improving their impacts on the pest populations and the economic bottomline of US farmers. The benefits of this project will extend way beyond the southern US as the methods developed can be modified or adopted by farmers in the other regions.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
215	2199	1130	100%

Knowledge Area
215 - Biological Control of Pests Affecting Plants;

Subject Of Investigation
2199 - Ornamentals and turf, general/other;

Field Of Science
1130 - Entomology and acarology;

Keywords

biological control

insect

natural enemy

Goals / Objectives
(1) Characterize and evaluate the effect of established natural enemies.(3) Implementation, evaluation, and enhancement of biological control. (4) Evaluate the benefits and risks of natural enemies.

Project Methods
The three objectives will be achieved through studies in two biological control systems. The first system is the biological control of oak lecanium scale on established willow oaks in the landscape through better understanding of the ecology, impacts and benefits of exisiting natural enemies. This system will be studied by determining the natural enemy complex of the oak lecanium scale in the landscape of SC through beat sheet sampling method, sticky card monitoring method, and collection and rearing of natural enemies in the laboratory. The benefits of the natural enemies in this system can be enhanced by careful studies on the competibility of the natural enemies with exisitng insecticides used for scale control and improvement of application techniques that will minimize the exposure of the natural enemies to the insecticides. The second system is the biological control of citrus mealybug in greenhouse ornemantal production through the introduction of Cryptolaemus montrouzieri and Leptomastix dactylopii, both of which are established natural enemies that are also sold commercially as biological control agents. Studies will be conducted to improve the impacts and benefits of these natural enemies by modifying the release sequence, timing and proportion of the the respetive natural enemies. Data from the studies in both systems will be analyzed with appropriate statistical analyses and results interpreted based on the combined effects of multiple natural enemies in the systems. Presentations will be provided at professional/scientific meetings and grower/clientele group meetings to disseminate and encourage discussion among the audience on the benefits and risks of multiple natural enemies in various systems. Peer-reviewed publications will also be prepared.

Progress 05/01/11 to 09/30/12

Outputs
OUTPUTS: The natural enemy fauna of two scale insect species, the oak lecanium scale (a soft scale, Coccidae) and Melanaspis deklei (an armored scale, Diaspididae), were characterized and their effects on the scale insect populations were evaluated (Objective 1). Samples of willow oak branches infested with oak lecanium scales were collected in the urban landscapes in Florence,SC, Griffin,GA, Raleigh,NC, and Virginia Beach,VA. 33 parasitoid species and 5 predator species (identification pending) were collected. By carefully examining the collected plant samples for parasitoid mummies, up to 25% of immature scale and 75% of adult scales were parasitized. Some of the adult scales continued to produce eggs even after parasitism; the influence of this observation on the actual impact of parasitoids on oak lecanium scale population is unknown and will be investigated. Sampling with yellow sticky cards indicated that the majority of parasitoid and predator species were most active during the enlargement of adult females and hatching of eggs, roughly April to June. 12 parasitoid and 2 predator species (identification pending) were collected from wax myrtle branches infested with Melanaspis deklei in Myrtle Beach, SC. The parasitoids and predators were active throughout the year. Up to 25% mortality of the scale insect population can be attributed to the parasitoids. Impacts of the predators of both the oak lecanium scale and Melanaspis deklei are more difficult to quantify. Two studies were conducted to develop methods in enhancing biological control (Objective 3). A study was initiated to determine the side effects of systemic neonicotinoids insecticides on the natural enemies of oak lecanium scale. The study was conducted on well-established willow oak trees in an urban landscape. The insecticides (dinotefuran and imidacloprid) were applied as soil drench, trunk spray or granular broadcast. A negative impact on the actions of natural enemies is expected when the post-treatment parasitism rate was lower than the pre-treatment data. This study is on-going. An additional study was conducted to determine the residual toxicity of chlorfenapyr against Amblyseius swirskii, a population commercial biological control agent for whitefly and thrips in greenhouses. Chlorfenapyr residue of up to 18 days was found to be moderately toxic to the predator mite. PARTICIPANTS: A Ph.D. student (Ernesto Robayo) is completing the survey of oak lecanium scale natural enemies. Additional data were provided by Drs. Kris Braman (University of Georgia), Pete Schultz (Virginia Tech) and Steven Frank (North Carolina State University). TARGET AUDIENCES: Both studies respond to the needs of nursery growers, landscape care professionals, arborists, plant managers, and homeowners for effective management of scale insects in urban landscapes and ornamental plant productions. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
A better understanding of the impacts of natural enemies is crucial to the development of an integrated pest management program. Knowing the predominant natural enemy species of the oak lecanium scale and Melanaspis deklei, we can design follow-up experiments to determine the actual impacts of these natural enemies in regulating the scale insects populations and the methods to employ to enhance their effectiveness. Since the parasitoids and predators of oak lecanium scale are active during the time of crawler emergence, we will have to revise the typical recommendation of spraying insecticides during the time of crawler emergence for scale insect control in order to minimize the negative impacts of the insecticide applications on the natural enemy populations. For Melanaspis deklei, topical application for crawler control may not be the best option because the natural enemies are always present. In this case, a specific period may need to be identified for targeted application knowing full well that some of the natural enemies may be impacted. Understanding how the natural enemies move within the same landscape may be the key to design such a targeted spray program to avoid eliminating the entire population and allow rapid recolonization by the natural enemies. Evaluating the compatibility of pesticides with biological control agents is an important step in designing an effective biological control system, particularly in ornamental plant systems where the extremely low economic threshold necessitate the use of pesticides. Results from these studies will allow ornamental plant producers and landscape care professionals to select pesticides that are the most compatible with natural enemies, thus reducing the pest population and conserving the natural enemy populations at the same time.

Publications

• No publications reported this period

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: A study on the biology and ecology of the oak lecanium scale has reported that egg hatch of the species occurred in May and extended into early June in SC. By holding mummies in plastic vials, 33 parasitoid and 5 predator species (identification pending) has been collected. Biological control by the parasitoids accounted for up to 25% of the mortality of the scale insect in the landscape. The impacts of the predators were not able to be determined because the predators were yet to be identified and highly mobile. By trapping with yellow sticky cards, the peak activity period of parasitoids was identified to be between April and June, coincide with the emergence of the scale insect crawlers. A study on the biology of the newly reported armored scale species, Melanaspis deklei, has reported 3 generations per year, with peak crawler emergence occurring in May, July and October-November. By keeping collected twigs in glass vials, 12 parasitoid and 2 predator species (identification pending) were collected. Up to 25% mortality of the scale insect population can be attributed to the parasitoids. Impacts of the predators are more difficult to quantify. Both the parasitoids and predators are active throughout the year. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Various audience. Both studies respond to the needs of nursery growers, landscape care professionals, arborists, plant managers, and homeowners for effective management of scale insects in urban landscapes and ornamental plant productions. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The impacts of the studies into the biology and ecology of the oak lecanium scale and Melanaspis deklei remains to be assessed. These scientific investigations help to provide better understanding and prediction of the pest status of these invasive pests of ornamental plants and trees. Understandings of the impacts of the natural enemies and when they become active are crucial to developing an integrated pest management program where the landscape care professionals can apply insecticides when the scale insect populations are most vulnerable and yet spare the natural enemies from the negative impacts of the insecticide applications.

Publications

• No publications reported this period