Nursery, Greenhouse, and Landscape News

Trap for Flying Insects Could Ease Lady Beetle Nuisance

A new indoor trap uses a blacklight to capture flying insects, including a pesky lady beetle species that sometimes clusters inside homes. The trap, invented by U. S. Department of Agriculture scientists in Georgia, doesn't the harm beneficial insects or use chemical insecticide. Instead, flying insects attracted by the blacklight are caught in a bag that has a non-stick surface. The insects are collected alive for subsequent release or disposal. Once commercially developed, this trap could provide relief to homeowners annoyed by lady beetles that enter their homes in large numbers in the fall. The insects are only seeking refuge from approaching winter, but they are a serious nuisance for many Americans.

In tests, the trap captured nearly 100 percent of Asian multicolored lady beetles (Harmonia axyridis). Many people prefer not to kill these lady beetles, but indoors and in large numbers, they can be bothersome. If agitated or squashed, the beetles can emit a foul smell and secrete a bright yellow substance that stains walls and fabrics. Researchers have applied for a patent and USDA's Agricultural Research Service is currently evaluating applications from companies interested in licensing the technology for commercial use. The new trap was developed by retired ARS scientist W. Louis Tedders, formerly with ARS' Southeastern Fruit and Nut Research Laboratory, Byron, Ga. The new trap is small-about 12 by 24 inches-and can be easily assembled or disassembled in as little as two minutes. If necessary, an insecticide can be added inside the bag for killing harmful pests.

Source:

USDA News Release, December 29, 1998

Aphid and Natural Enemy Movement in Mum Greenhouses

Different species of aphids have different population spatial structures that can influence pest control by natural enemies. For example, green peach aphid moves rather rapidly through a greenhouse and does not reach as high densities on individual plants as will the slower-moving cotton aphid. Successful biological control within such spatially structured populations requires natural enemies to locate relatively scarce patches of prey soon after they colonize a chrysanthemum plant.

The dispersal abilities of different natural enemies influence their effectiveness in controlling aphids on chrysanthemum. Aphid biological control may be improved by releasing sufficient numbers of high-quality natural enemies into the greenhouse and at enough points to facilitate aphid patch location. Green lacewing larvae don't disperse as well as the parasitoid Aphidius colemani does. The wasp was able to spread across nearly 14 ft2 of greenhouse space, whereas third instar lacewings may only spread over 3/4 ft2 of space within 10 hours of their release. However, once they've found an aphid patch, both species are about as efficient in destroying aphids (by eating or parasitizing them). To achieve equal aphid suppression, more of the slower-moving species need to be introduced and from more points. To completely cover a target area within 10 hours of their release, A. colemani should be released from points within the greenhouse no greater than 10-3/4 feet apart. Green lacewings should be released from points within individual benches--since they're unable to move to adjacent benches--no greater than 2-1/4 feet apart.

Other factors, however, may affect natural enemy dispersal enough to change these general guidelines for distances between release points--including natural enemy quality, the number and distribution of aphid patches around the release point, plant cultivar and age, and environmental conditions, such as temperature, humidity and light levels.

Source:

Heinz, K. M. 1998. Dispersal and dispersion of aphids and selected natural enemies in spatially subdivided greenhouse environments. Environ. Entomol. 27(4): 1029-1038.


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