First Japanese Beetle Collected in Texas:
Dr. Bastiaan M. Drees, Professor and Extension Specialist
Department of Entomology
Texas A&M University
College Station, TX
Japanese beetles, Papillia japonica Newman (Coleoptera: Scarabidae), are serious pests of turf and ornamental plants in the states east of the Mississippi river except Florida, Mississipi and Minnesota. This is an imported pest species and has previously not been reported from Texas. Recently, surveys conducted by the United States Department of Agriculture's Agricultural & Plant Health Inspection Service/Plant Protection & Quarantine (USDA APHIS/PPQ), using pheromone and floral scent baited traps to attract adult beetles, have documented the occurrence of this pest in Texas at the following locations: In the Dallas/Fort Worth metroplex, a total of 62 Japanese beetles were trapped at four nurseries and one golf course. In the Austin metropolitan area, 16 Japanese beetles were trapped at a single nursery. All of the finds at nurseries were associated with balled/burlaped and containerized trees.
Description. Adult beetles are about 1/2 inch long and are shiny, metallic green. They have coppery-brown wing covers (elytra) and six small patches of white hairs along the sides and the back of the body (abdomen) under the edges of the wings. Larvae are similar to other species of white grubs, and are off- white in color, have a brown head, and are found in a curled, C-shaped position. Full-grown grubs are about 1 inch long.
Life Cycle. Japanese beetles spend 10 months of the year in the soil as grubs, feeding on plant roots. Adults begin to appear in mid-June and are active for approximately 4 to 6 weeks.
Plant damage. Grubs attack turfgrass as well as roots of nursery stock and produce damage similar to that produced by other species of white grubs. Roots are consumed, causing turfgrass to turn yellow and die in patches. Upon examination, the turf can sometimes be "rolled up" like a carpet due to lack of roots. Adult beetles feed on leaves, flowers and fruit of a wide variety of ornamental and food plants, often feeding on loose groups or aggregates. Feeding produces tattered-looking leaves, as beetles chew out the tissue between the veins leaving a lace-like skeleton or eat away large irregular areas. One of the plants particularly attractive to adults is rose.
ConserveÆ SC (SPINOSAD) A New Pesticide for Texas Growers:
Conserve SC (DowElanco), containing spinosad is registered for a variety of insect and mite pests of outdoor nursery and ornamental plants (woody and herbaceous), including:
beetles (chrysomelid leaf-feeding beetles) caterpillars (bagworm, beet armyworm, eastern tent caterpillar, fall webworm, hickory tussock moth, spruce budworm, yellownecked caterpillar) fly larvae (honeylocust pod gall, serpentine leafminer) sawflies (exposed larvae) thrips (exposed Cuban laurel, western flower thrips) spider mites (two-spotted).
It has a 4 hour Restricted Entry Interval (REI) and a CAUTION signal word. Spinosad (pronounced "spine- oh-sid") is a novel product with a mode of action unique from conventional nerve-active insecticides. The name for this new insecticide class is spinosyn.
Discovery. The product is produced by a microorganism, Saccharopolyspora spinosa, a rare actinomycete bacterium reportedly collected from soil in an abandoned rum distillery on a Caribbean Island in 1982 by a vacationing Eli-Lilly scientist. It has not been found in nature since that time, and was subsequently described as a new species. The bacteria produces compounds (metabolites) while in a fermentation broth. The first novel fermentation-derived compound, spinosad, was characterized in 1988 and since that time over 30 different compounds ("spinosyns") have been found. Further manipulation of these chemicals could yield even more compounds ("spinosoids"). Chemicals produced in this manner are often called fermentation products (such as abamectin or AvidÆ).Chemical characteristics. Conserve SC actually contains two chemicals, spinosyn A and spinosyn D. These are crystalline solids with low odor, no volatility, and with low water solubility. Soil sorption is moderately strong and they degrade primarily through photolysis. The half life of these compounds on a plant leaf is about 2 days. When sprayed on leaves, the compounds have translaminar movement: they move from one leaf surface to the other through the leaf tissue. Phytotoxicity has not been observed at the 1x and 2x rates of the water-based formulations tested to date.
Target specificity. Conserve SC has a "moderate" spectrum of activity. It is most effective on chewing insects including beetles (particularly Chrysomelidae), caterpillars and sawfly larvae. Leafmining flies, fungus gnat and shore fly larvae are also potential target pests. It appears to have good activity on thrips and sporadic activity against mite species. Although active against hymenoptera (honey bee LC50 = 11.5 ppm; Encarsia formosa LC50 = 29.1 ppm as topical treatments), toxicity of dry residues should be less toxic. No "flare-ups" of aphid populations have been observed after treatment. Sucking insects are not affected unless very high concentrations are applied.
Mode of action. Spinosad causes excitation of the insect nervous system, leading to involuntary muscle contractions, prostration with tremors, and finally paralysis. These effects are consistent with the activation of nicotine acetylcholine receptors by a mechanism that is clearly novel and unique among known insect pest control products. Spinosad also has effects on GABA receptor function that may contribute further to its insect activity. The reason for extraordinary margins of selectivity between certain insects, mammals, and other non-target organisms is not fully understood. In target organisms, the compound is 5 to 10 time more effective when ingested than when used as a contact insecticide. As such, the chemical has little effect on sucking insects. Spinosad is considered to be a "fast-acting" insecticide with a performance profile similar to synthetic insecticides like pyrethroids. Death occurs in 1 to 2 days and there appears to be no recovery. Generally, treatment provides 7 to 14 days of control. Although spinosad is thought to have a novel mode of activity, resistance management is perceived to be an essential practice in perpetuating the long-term effectiveness of this insecticide.
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