2012 Highlights: UC IPM Annual Report

Chamomile seed bug. Photo by S. Swain.

Virginia creeper leafhopper nymph. Photo by M. Poe.

Brown marmorated stink bug nymph and adult.

Non-native bugs invade california

The influx of invasive species has been on the rise in the last decade. One recent arrival from Mediterranean Europe is the chamomile seed bug, Metopoplax ditomoides, first detected on the West Coast in Oregon in 1998 and in California’s Sonoma County in 2002. This insect is a nuisance to homeowners when it swarms over vehicles and invades houses and other buildings in large numbers in the spring and summer. It has created costly control expenses for commercial firms and has sometimes led to loss of business. Yet excluding this insect from structures is very difficult due to its small size (1/8–1/6 inch).

UC IPM advisors Lucia Varela and Steven Swain have been studying the chamomile seed bug’s life cycle and the host plants where this insect feeds and breeds. Varela and Swain are also investigating possible natural controls. In their studies, they have recovered a parasitic wasp that attacks the eggs of the chamomile seed bug.

This particular seed bug feeds and lays its eggs on brassbottoms, Cotula coronopifolia, a plant native to South Africa. Brassbottoms form carpets of yellow flowers in marsh tidal pools surrounding the San Pablo Bay and the Petaluma River, and these extensive patches of flowers harbor large populations of the chamomile seed bug.

Another invasive insect Varela is investigating, this one in collaboration with Mendocino County Viticulture and Plant Science Advisor Glenn McGourty, is the Virginia creeper leafhopper (VCLH), Erythroneura ziczac. VCLH is similar in appearance and life cycle to the native western grape leafhopper (WGLH), Erythroneura elegantula. The difference is that WGLH is well controlled by a complex of Anagrus species egg parasites while VCLH is not. While insecticides that effectively control WGLH also control VCLH in conventional vineyards, in organic vineyards VCLH control is more difficult due to the lack of natural controls, 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. Most recently it has been detected in the North Coast counties of Mendocino and Lake. (Learn how to distinguish leafhoppers in Northern California vineyards.)

Another invasive species of concern is the brown marmorated stink bug, Halyomorpha halys. This insect was first reported in Pennsylvania in 1996, and by 2010 huge populations were causing extensive damage to the fruit industry in the Middle Atlantic states. The brown marmorated stink bug was first detected in California in 2002, and it is now established in the Los Angles area. Adults and nymphs suck juices from fruit and seeds, creating pockmarks and distortions that make fruit and vegetables unmarketable. To aid in early detection, UC IPM developed a Pest Alert card available online. For more information about this new Pest Alert series, see the Resources section of this publication.

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