This article was originally published in the June 2013 issue of the Retail Nursery and Garden Center IPM News.  Read the entire article at http://www.ipm.ucdavis.edu/RETAIL/retail-newsletter.html  

Adult mosquito.  Photo by Jack Kelly Clark

Many gardeners are adding fountains, ponds, and other water features to their landscapes. Water gardens are beautiful and calming, but, if not managed properly, can add an unpleasant element to the landscape—mosquitoes. How can you help prevent mosquito infestations?

Mosquitoes can be managed using an integrated approach that relies mostly on prevention, using biological and chemical controls when necessary. The key strategy is to eliminate all potential breeding sites; even one ounce of standing water can support a population of larvae. What can be done, however, when an outdoor space contains a water element? Here are a few tips.

Water features in the landscape will invariably attract adult mosquitoes, but attempting to control them or prevent their egg laying is difficult. Larvae are easier to manage, since they are concentrated in known areas, don't yet bite, and can't fly away. Larvae prefer shallow water that is less than 24 inches deep, so install water features that are deeper than 2 feet. Ponds or features that provide a steep slope or have vertical walls that quickly drop off into deep water will also be less favorable to mosquitoes. Adding a fountain, waterfall, or other device increases water circulation and reduces the stagnation that allows mosquitoes to breed.

Remove excess vegetation and organic debris that provide mosquito larvae with food, shelter from the sun, and hiding places from predators.

In natural environments, bacteria, nematodes, other insects, crustaceans, and fish often keep numbers of mosquito larvae low. Conserve predators such as dragonflies and backswimmers, which may have colonized ponds, by avoiding broad-spectrum insecticides and consider introducing fish. County vector control services may provide free mosquito fish, voracious consumers of mosquito larvae and pupae. Never release mosquito fish into natural water bodies, since these fish aren't native to California and can disrupt ecosystems.

Although these measures will prevent problems in most cases, mosquito larvae may still develop in some ponds.

In gardens with lots of plants growing in still water, it may be impossible to keep mosquitoes from breeding. Regularly check water features for larvae, which periodically come to the surface to breathe through abdominal siphons Watch for the larvae's characteristic wriggling movement, or use fine dip nets to monitor for larvae. It is important to act quickly to kill mosquitoes when they are small, easiest to manage, and before they become adults and start biting.

Larvicides containing spores or metabolites of the bacterium Bacillus thuringiensis israelensis (Bti) (e.g., Mosquito Dunks, Mosquito Bits, Microbe-Lift, and other products) act as stomach poisons when ingested, killing larvae within a few days. Bti affects only fly larvae, so it won't harm predatory insects living in the pond or water feature. Another effective larvicide is the insect growth regulator (IGR) methoprene (e.g., Pre-strike Torpedos). IGRs interfere with larval molting and also take a few days to kill, but they have a broader spectrum of activity, affecting most juvenile insects and other arthropods that might be in the pond. Both Bti and methoprene are available as granules or pellets, remain effective for about a month, and as with all pesticides, should be used only according to label directions.

For more information about mosquitoes, visit http://www.ipm.ucdavis.edu/PMG/PESTNOTES/mosquitoes.html.

Written by: Andrew Sutherland, UCCE Alameda and UC Statewide IPM Program, San Francisco Bay Area amsutherland@ucanr.edu

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Egg, five nymphal stages, and adult bed bugs, Cimex lectularius. Photo by Dong-Hwan Choe.

Bed bugs are quickly becoming major household nuisance pests. California has recently experienced a multitude of bed bug reports, with San Francisco now considered one of the Top 10 most infested cities in the country.  Bed bug detection can be very difficult and almost always requires special training since bugs prefer to hide in dark, inaccessible cracks and crevices near their hosts' resting spots.  An experienced pest management professional can examine all possible harborages in a home, searching for the bugs themselves and signs of infestation such as the characteristic black fecal spotting and cast nymphal skins, although low-density infestations may escape detection.

Thankfully, several monitors are available that attract or intercept bed bugs. Bed bug monitors fall within one of two categories: active monitors and passive monitors. Active monitors employ attractants—heat, carbon dioxide, host odors (kairomones), pheromones, or a combination of these—to lure bed bugs out of their hiding areas and into a pitfall or sticky trap within the monitor. These devices have the potential to detect bed bugs in the absence of a host (vacant room).  Passive monitors either exploit a bed bug's affinity for dark crevices or rely on chance encounters with pitfalls or sticky traps. Interceptor monitors are pitfall devices that rely on the presence of a host (a sleeping human) to attract hungry bugs and trap them en route to their meal.

A team of UC researchers led by UC Berkeley entomologist Vernard Lewis recently evaluated a series of five bed bug monitors.  Overall the study concluded that active monitors recovered a steady proportion of bed bugs as densities increased and that all monitors tested were able to detect bed bugs at low densities.

Read more in the February 2013 issue of the UC IPM Green Bulletin.  More information on bed bug biology and management is available in the just revised Pest Note: Bed Bugs on the UC IPM web site.

-Andrew Sutherland, UCCE Alameda and UC Statewide IPM Program, San Francisco Bay Area amsutherland@ucanr.edu

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Life states of the goldspotted oak borer.  From left: fourth-instar larva, fourth instar larva in a hairpin configuration and in a constricted form, pupa and adult.  Photo by Mike I. Jones

First identified in California in 2004, the goldspotted oak borer (GSOB), Agrilus auroguttatus, has killed more than 24,000 oak trees in San Diego County since its arrival, probably in the late 1990s.   In 2012, it was detected in Riverside County and it is expected to spread northward in the state. 

The most seriously damaged oaks are those in the red oak group including coast live oak, Quercus agrifolia, and black oak, Q. kelloggi.   It also infests canyon live oak, Q. chrysolepis but has not been found to kill the other native oak species in the area, the Englemann oak, Q. englemanni.  So far losses have been most serious in parks and forested areas, but landscape trees are also being killed.

A new Pest Note from the UC IPM program outlines management guidelines for this serious pest.  Flatheaded borers such as GSOB are difficult to manage and seriously infested trees cannot be saved. The primary way GSOB spreads into new areas is through the movement of infested wood and the authors recommend leaving infested wood on site for 2 years.    If wood is to be moved, the Pest Note provides guidelines for treating it through containment, grinding, and debarking.   Guidelines for replanting infested areas, less susceptible oak species, biological control, insecticide applications and developing GSOB management plans are also described. 

Many other borers attack oaks but do not kill trees.  GSOB infested trees can be distinguished by the characteristic D-shaped emergence holes it leaves behind.  A special feature of the Pest Note is a table illustrating the emergence holes of borer species on southern California oaks.  Many photos are also included.

The information in this Pest Note: Goldspotted Oak Borer is based primarily on research studies by the authors:  Mary Louise Flint (UCIPM and Entomology/UC Davis), Tom Coleman and Steve Seybold (USDA/US Forest Service), and Mike Jones (Entomology/UC Davis).  Find it at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74163.html

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Nymph of the Virginia creeper leafhopper (VCLH), Erythroneura ziczac.  It is a new invasive pest on grapes.
(Photo by Mike Poe, UC IPM)

The influx of invasive species has been on the rise in the last decade.  One invasive insect recently detected in the North Coast counties of Mendocino and Lake is the Virginia creeper leafhopper (VCLH), Erythroneura ziczac. UC IPM Advisor Lucia Varela, in collaboration with Mendocino County Viticulture and Plant Science Advisor Glenn McGourty, is investigating VCLH.  VCLH is similar in appearance

and life cycle to the native western grape leafhopper (WGLH), Erythroneura elegantula. View the videos to distinguish the two species. The difference is that WGLH is well controlled by a complex of Anagrus species egg parasites while VCLH, as a new invasive, is not. While insecticides that effectively control WGLH also control VCLH in conventional vineyards, in organic vineyards VCLH control is more difficult due to high populations, and damage has been observed. Native to the northern Midwest, VCLH was first spotted in Northern California in the late 1980s. Since then it has been moving southward and was detected in the northern Sacramento Valley and northern Sierra Foothills by 2008.

See UC IPM's 2012 Annual Report for more news on non-native bugs invading California. 

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