The Development of Integrated Pest Management in Floriculture Progress Report — September 1994
Date September 7, 1994
Title of Project Development and Implementation of Integrated Pest Management Strategies in Floriculture
Institution where work is being conducted University of California, Davis
Amount of Endowment rGrant$ 30,000
Covering Period 1/94 to 12/94
Anticipated Date of Project Completion/Final Report Project is ongoing.
Individual(s) Conducting Project:
(List Project Leader First)
Michael P. Parrella - Title Professor
Telephone Number (916) 752-0492
Development and Implementation of Integrated Pest Management Strategies in Floriculture
University of California, Davis
- A. Project Objectives:
- 1) a. Evaluate the potential of a new nematode species, Thripinema aptini, discovered in a rose growers range in
California, for control of the western flower thrips. Examine the feasibility of utilizing the predatory bug, Orius sp., the
predaceous mite, Amblyseius cucumeris, and the nematode, Steinernema carpocapsae, for control of the western flower
thrips. Explore the basic biology of a new parasitoid discovered in California (Ceranisus sp.) which attacks the western
flower thrips; b. Continue the evaluation of natural enemies, on a comparative basis, for biological control of selected pests
in greenhouses; c) Continue studies on the commercially available predator, Chrysoperla spp., and the commercially
available parasitoid, Aphidius solani, for aphid control; d. Continue statewide implementation of an IPM/biological control
program for potted chrysanthemums and expand this to cut chrysanthemums.
- 2) Continue the basic biology of thrips in an
effort to understand feeding, oviposition, and pupation behavior in selected floriculture crops.
- 3) Continue the search for new
pesticides which have potential for use in floriculture and maintain contact with chemical manufacturers to assure that the
ornamentals industry is not overlooked for potential registrations. Assist in labeling materials for ornamentals and help fill
in data gaps for materials undergoing reregistration. Evaluate new and old pesticides for compatibility with selected natural
enemies in culture at UC Davis. Continue monitoring for insecticide resistance in the western flower thrips and develop
alternative strategies for controlling these arthropods and for managing the development of resistance.
- 2) Continue the basic biology of thrips in an
- B. Major New Advancements Over the Preceding Twelve Months:
- Three major floriculture production areas in California were sampled in November 1993 and in March and June
1994 for western flower thrips parasitized by the nematode, Thripinema aptini. This nematode was found parasitizing
western flower thrips in 1993 (a now California record at that time) and we were interested in determining its general
prevalence in the state. In addition, we hoped to be able to determine if intraspecific groups of this nematode were present in
California. The practical implication of this is that if we found higher levels of western flower thrips parasitized by this
nematode in Santa Barbara vs. San Diego, there could be a genetic basis for this difference rather than a simple
environmental explanation. If this proved to be true, then rearing and conducting experiments with the nematode strain from
Santa Barbara (with its greater inherent ability to parasitize western flower thrips) would be the path of choice. Determining
if genetic differences among these nematode populations exist in the state requires genetic fingerprinting techniques that are
reliable. As we started this work, there were few such techniques developed for thrips, let alone the nematode species
parasitizing the thrips. It was necessary to develop these techniques.
- Interestingly, populations of western flower thrips and their natural enemies were highest in carnations produced in
greenhouses in Santa Barbara County and in field grown roses in Monterey County. The dominant natural enemies were the
parasitic nematode, T. aptini, and the two predators, Orius tristicolor and Amblyseius sp. From these samples we selected
groups of thrips parasitized by the nematode for genetic fingerprinting. Preliminary experiments with the thrips and
nematodes allowed the selection of five primers (from Operon Technologies [Kit A]) and we then tested the reliability of the
random amplified polymorphic DNA technique (RAPDs) by comparing nematode and western flower thrips RAPDs banding
patterns. Data collected to date indicate that RAPDs is a reliable technique for nematode fingerprinting if contamination and
misrepresentation of the presence or absence of bands is taken into consideration To correct for contamination, the western
flower thrips from which the nematode was extracted is also subjected to RAPDs. Any bands from the nematode and thrips
that co-migrate are not scored in the analysis. To correct for misrepresentation of the bands, the reaction is repeated four
times. Presently we are determining the validity of RAPDs by exan-diting banding patterns from a family of nematodes. If
the RAPDs fingerprints show a pattern of inheritance, then we will be able to compare and contrast different nematode
populations found throughout California. Thus we will be able to select that population of nematodes which provides the
highest level of parasitization in the state for subsequent biological and efficacy studies.
- Weekly releases of the predators Orius sp. and A. cucumeris were made into a commercial range of cut
chrysanthemums where western flower thrips and Tomato Spotted Wilt Virus were a problem. These natural enemies
dramatically reduced thrips populations when contrasted with control (no release) cages and with an adjacent grower
greenhouse under chemical control. However, populations of western flower thrips and the incidence of the virus were above
acceptable levels. Other biological solutions to the problem of western flower thrips on floriculture crops are needed. Data are
still being analyzed from this trial and we hope to extract information on the spatial distribution of western flower thrips as a
function of planting data; this will be used to develop population and decision level sampling plans for this pest.
- Biological studies were initiated with the parasite Ceranisus sp. In addition, we sent this species to cooperating
scientists in the Netherlands (Agriculture University, Wageningen) where they are comparing members of this genus from
around the world. The objective is to determine if there is a “best” Ceranisus to use in biological control trials. Our studies
have shown that this parasite prefers to attack early stages of the thrips although we have found that the first pupal stage was
parasitized. The implication here is that this natural enemy may behave in a way that is similar to A. cucumeris which also
attacks only first and early second instars of the western flower thrips.
- We continue to make great strides in our evaluation of natural enemies for whitefly control (pubs. 1-7). When we
publish articles every effort is made to publish in scientific journals (i.e., Environmental Entomology) and then extract
information from these to publish in grower oriented magazines (i.e., Greenhouse Grower, California Agriculture). We
continue to evaluate new natural enemies in a cooperative agreement with the USDA/APHIS laboratory in Mission, TX and
with the California Department of Food and Agriculture in Sacramento, CA. Data on at least seven “new” natural enemies are
being analyzed at this time. In addition, we are in the process of evaluating and comparing several different species of fungi
(Paecilomyces, Beauveria, and Metarhizium) for whitefly control.
- Weekly releases of the predators Chrysoperla rufliabris and A. solani were made into a commercial range of cut
chrysanthemums where aphids were a serious problem. Release rates suggested by commercial insectaries were used and
releases were initiated when aphids were first observed in the crop. Unfortunately, aphid populations quickly zoomed out of
control. We even tried to reduce the aphid populations with repeated application of selective insecticides (soap and kinoprene)
but this did not result in acceptable aphid control. This chrysanthemum crop represented a worst case scenario with four
species of aphids present on the chrysanthemums and emigration a constant problem. In such a situation, other strategies
(including new biological control agents) are needed. Studies on a much smaller scale have shown that the convergent lady
beetle has the potential to control aphids on potted chrysanthemums (pub.
.
- Research has continued with developing a predictable biological control program for chrysanthemums (pub. 9). We
routinely send leafminer parasites to cooperative growers in San Diego, Santa Barbara and Salinas who try them on a number
of leafminer sensitive crops with the advice provided by our system. We can achieve reliable biological control of leafminers
on chrysanthemums. Successful strategies for the biological control of other pests, such as aphids and western flower thrips,
must be added to this model before a complete program can be presented to growers.
- In the war against silverleaf whitefly, Bemisia argentifolii, (formerly Strain B of the sweetpotato whitefly) attacking
greenhouse and field crops, the use of insecticides classified as insect growth regulators (IGRs) offer the potential of whitefly
control with minimal disruption to the environment and with considerable reduction in hazards to greenhouse worker health
and safety. Four IGRs (buprofezin, s-kinoprene, fenoxycarb and pyriproxifen) were applied to eggs, first and second instars,
third and fourth instars and pupae of B. argentifolii on poinsettia plants in separate greenhouse/laboratory experiments.
Mortality readings were taken every seven days following a single application of each material until adult emergence in the
controls was complete. Any adults surviving the IGR applications were evaluated for their ability to lay eggs by contrasting
their fertility against control adults.
- No material had a strong effect on the egg stage, although appreciable mortality (as high as 88% with buprofezin)
was recorded as subsequent immature development continued on the treated leaves. This appeared to be due to the residual
effects of the material on developing immatures rather than mortality to the egg state. When applied to first and second
instars, buprofezin and pyriproxifen provided >95% mortality and kinoprene gave ca. 85% mortality; there were no
differences between mortality provided by fenoxycarb and the control. None of the IGRs evaluated had any appreciable
impact when applied to third and fourth instars or pupae. In addition, when adults surviving IGR application as various
immature stages were evaluated for fertility, no effects were observed compared to the control.
- Results strongly support the concept of proper timing of IGR application to coincide with early developmental
stages of B. argentifolii. Information on the distribution of whitefly life stages in a poinsettia crop (obtained through a
formal monitoring program) can be used to time sprays which will maximize control of whiteflies with any IGR. The stage
specific nature of these IGRs suggests compatibility with parasitoids; these natural enemies prefer to lay eggs in third and
fourth instars. The issue of compatibility is currently being addressed in my laboratory.
- Interestingly, populations of western flower thrips and their natural enemies were highest in carnations produced in
- C. Future Plans Covered by the Endowment Grant:
- Large trials are planned with biological/IPM programs in chrysanthemums, poinsettias and other crops where we
will be testing the most effective natural enemies for control of whiteflies and thrips. These trials will be done with
cooperating growers as well as in my greenhouses on the Davis campus. As discussed above, we am particularly interested in
examining the interactions of different natural enemies used simultaneously for biological control. Considerable research will
concentrate on the new natural enemies of western flower thrips. Detailed studies with many floriculture pests and their
natural enemies will continue–the more data we have the better we are able to formulate control IPM strategies using either
pesticides, natural enemies or a combination of the two. The amount of time and effort that goes into studying biology in
this project should not be underestimated because a good portion of the six graduate students supported by this AFE grant
have basic biology as an important component of their Master’s and Ph.D. work. Research with new “biorational” and other
pesticides will continue in an effort to generate data required for registration. Compatibility studies with natural enemies win
also continue.
- D. Anticipated Benefits for Floral Industry:
- This AFE project is designed to provide flower growers with components of an IPM program which can be applied
in their operations for the purpose of maintaining quality of production while reducing the pesticide use. This is
accomplished at two levels: 1) some data generated by the project is of immediate use to growers (pesticide efficacy,
information on basic biology in relation to pesticide efficacy, how to estimate pest populations in the greenhouse, evaluation
of commercially available natural enemies. etc.) and can be applied to production facilities without delay; and 2) other data is
being compiled which focuses on the development of a mom complete system where biological control is a major component
of an IPM program for floriculture crops. While this data is not of immediate use to growers (for example, some of the
natural enemies we are working with for biological control of the silverleaf whitefly and western flower thrips are not yet
available commercially) we are building the knowledge base for a fully integrated pest control program that can be adopted
by growers in years to come.
- E. References Cited:
- 1. Heinz, K.M., J. Brazzle, C.H. Pickett, E.T. Natwick, J.M. Nelson, and M.P. Parrella. 1994. Delphastus pusillus
as a potential biological control agent of sweetpotato (silverleaf) whitefly. California Agriculture 48(2):35-40.
- 2 . Heinz, K.M. and M.P. Parrella. Biological control of Bemisia argentifolii (Gennadius) (Homoptera: Aleyrodidae)
infesting Euphorbia pulcherrima: evaluations of releases of Encarsia luteola Howard (Hymenoptera, Aphelinidae)
and Delphastus pusillus LeConte (Coleoptera: Coccinellidae). Environmental Entomology (in press).
- 3 . Heinz, K.M. and M.P. Parrella. Biological control of silverleaf whitefly on poinsettia. California Agriculture (in
press).
- 4. Heinz, K.M. and M.P. Parrella. Poinsettia (Euphorbia pulcherrima Wind. ex Koltz) cultivar-mediated differences
in performance of five natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Biological
Control (in press).
- 5&6. Heinz, K.M. and M.P. Parrella. Parasites and predators control silverleaf whitefly infesting poinsettia greenhouses.
Greenhouse Grower (two articles in press in two successive issues of the magazine).
- 7. Nelson, J. and M.P. Parrella. Natural biological control occurring on poinsettias; how a grower can tell. Greenhouse
Grower (in press).
- 8. Flint, M.L., S.H. Dreistadt and M.P. Parrella. Releases of convergent lady beetle can control aphids on potted
plants. California Agriculture (in press).
- 9. Heinz, K.M., L. Nunney and M.P. Parrella. 1993. Toward predictable biological control of Liriomyza trifolii
(Diptera: Agromyzidae) infesting greenhouse chrysanthemums. Environmental Entomology 22:1217-1233.
- 2 . Heinz, K.M. and M.P. Parrella. Biological control of Bemisia argentifolii (Gennadius) (Homoptera: Aleyrodidae)
