The Development of Integrated Pest Management in Floriculture Progress Report — December 1994
Date December 31, 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 nematodes, 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. e. Continue statewide implementation of an IPM/Biological control program for
potted chrysanthemums and expand this to cut chrysanthemums.
biology of thrips in an effort to understand feeding, oviposition, and pupation behavior in
selected floriculture crops.
potential for use in floriculture and maintain contact with chemical manufacturers to
assure that the ornamental’s 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.
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 new 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.
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 5 primers
(from Operon Technologies [Kit AT) 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 4 times. Presently we are determining the validity of RAPDs by examining
banding patterns from a family of nematodes. However at this point, results are not
encouraging. The RAPDs fingerprints do not show a pattern of inheritance, which makes
it difficult to compare and contrast different nematode populations found throughout
California.
into a commercial range of cut chrysanthemums where western flower thrips and Tomato
Spotted Wilt Virus was 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 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 date; this will be used to develop
population and decision level sampling plans for this pest.
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 parasitized. The implication here is that
this natural enemy may behave in a way that is similar to Amblyseias cucumeris which
also attacks only 1st and early 2nd instars of the western flower thrips.
whitefly control. (see publication #s 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, Texas and with the
California Department of Food and Agriculture in Sacramento, CA. Data on at least 7
‘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.
made into a commercial range of cut chrysanthemums where aphids were serious
problems. 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 4 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
(publication # 8).
for chrysanthemums (see publication #9). We routinely send leafminer parasites to
cooperating 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.
whitefly and may fit well into an integrated pest management program. Many of these
materials have characteristics that are favorable for an insecticide in the 1990s: low
mammalian toxicity, reduced residual activity, short re-entry intervals after application,
no hazard to the health and safety of farm workers, lack of problems with ground water
contamination, good activity against the target pest, compatibility with natural enemies,
and no impact on non-target organisms. Although it is rare to find all these qualities in a
single material, the IGRs (and particularly the juvenoids) are gaining a great deal of
attention. Many of these materials are used for whitefly control in other parts of the
world (Europe, Japan, Israel, etc.) and registration is being pursued for some of these
materials in the United States. We evaluated four insect growth regulators (buprofezin,
pyriproxifen, kinoprene and fenoxycarb) for their ability to kill the various immature
stages of the silverleaf whitefly and for their potential compatibility with natural enemies
of this pest. The materials buprofezin and pyriproxipfen provided the best control, and
activity was highest against the early instars of the whitefly. Such limited activity
suggests that these products, acting alone, may be insufficient to control the silverleaf
whitefly. However, if the materials are compatible with the natural enemy complex
attacking this pest, then these IGRs may fit into an IPM program where both the natural
enemy complex and the insecticide cause mortality to the whiteflies. Adult parasitoids
readily oviposited in whiteflies treated with any IGR and parasitoid emergence was
recorded from all treatments. However, only pyriproxifen showed no significant
difference in parasitoid emergence when compared to the control. We are still in the
process of evaluating the viability of these treated parasitoids. Similar results were found
when these materials were evaluated for compatibility with a predatory coccinelid beetle.
Only pyriproxifen was found to have no impact on larval development or adult longevity.
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 are 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 6 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 will also
continue.
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 more complete system where biological
control is a major component of an IPM program for floriculture crops. While this data is
;1800fnot 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.
Parrella. 1994. Delphastus pusillus as a potential biological control agent of
sweetpotato (silverleaf) whitefly. California Agriculture 48(2): 35-40.
(Gennadius) (Homoptera: Aleyrodidae) infesting Euphorbia Pulcherrima:
evaluations of releases of Encarsia luteola Howard (Hymenoptera; Aphelinidae) and
Delphastuspusillus LeConte (Coleoptera: Coccinellidae). Environmental.
Entomology (in press).
poinsettia. California Agriculture. (in press).
Koltz) cultivar-mediated differences in performance of five natural enemies of
Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Biological Control (in
press).
silverleaf whitefly infesting poinsettia greenhouses. Greenhouse Grower ( 2
articles in press in 2 successive issues of the magazine).
(10): 98 - 103.
beetle can control aphids on potted plants. California Agriculture (in press).
control of Liriomyza trifolii (Diptera: Agrornyzidae) infesting greenhouse
chrysanthemums. Environmental Entomiology 22: 1217 - 1233.
