Lace bug

Scheme 1 Defensive compounds from lace bugs (Tingidae)...

Scheme 2 Defensive compounds from Stephanitis lace bug spp...

Lace bugs in the genus Corythucha produce the isomeric 2-acyl-3,6-dihy-droxy-2-cyclohexene-l-ones, with a different pattern of oxygenation [45, 51, 52]. These were synthesized from 1,3-cyclohexanedione 11 (Scheme 3), with key steps being acylation to give 12, protection of the 1,3-dicarbonyl as the isox-... 

Scheme 3 Synthesis of lace bug chemical defense compounds...

Paraffinic oil is a refined petroleum distillate. This pesticidal oil is effective against aphids, lace bugs, leafhoppers, leafminers, mealybugs, scales, psyllids, whiteflies, thrips, and mites on vegetables, fruit and nut trees, landscape trees, shrubs, and flowing plants. 

In the seventeenth century the first naturally occurring insecticide, nicotine from extracts of tobacco leaves, was used to control the plum curcuUo and the lace bug. Hamburg (1705) proposed mercuric chloride as a wood preservative and a hundred years later Prevost described the inhibition of smut spores by copper sulfate. 

Leaves and flowers deformed, yellowish small, tarlike spots on undersidies. Cause Lace bugs. These small pests with lacy wings cause yellow-brown le lf spots. Dark brown droppings on lower leaf surfaces confirm their activity. Remove debris in spring and fall to deter overwintering. For severe problems, spray superior oil, insecticidal soap, or pyrethrin. 

Leaves pale and mottled. Cause Lace bugs. These /s - A", dark-colored bugs have lacy wings. They feed on the undersides of leaves and deposit small black spots of excrement. Severe infestations can cause early leaf drop. Control by spraying leaves with superior oil or insecticidal soap. 

Leaves turn yellow, then brown. Cause Lace bugs. Leaves eventually die. These flat, gray to brown, Vio" long insects have lacelike wings and feed on the undersides of leaves. Treat plants with a commercial pyrethrin spray or dust if damage is severe. Prevent problems by covering plants with row cover until they flower. 

Cause Sycamore lace bugs. This widespread and serious pest feeds on the undersides of planetree foliage. As the Vio", silvery white lace bugs feed, they puncture the leaves and then exude a toxin that turns the area around these punctures red or yellow. Spraying leaves with insecticidal soap just after the leaves unfold should control this pest. 

Leaves stippled with white. Cause Oak lace bugs. Adult lace bugs are Vio", flattened, dark insects with lacy-pattemed, silvery white wings. Both the adults and the tiny nymphs feed on the undersides of leaves, sucking the sap and producing a gray, splotched or stippled appearance to the upper sides of the foliage. Leaves may curl, turn brown, and drop... 

Leaves wrinkled and discolored. Causes Aphids willow lace bugs. See Leaves wrinkled and discolored on page 235 for more information on aphids. 

Willow lace bug adults and larvae also feed on willow leaves, causing severe discoloration. These A - A" pests have distinctive lacy wings and commonly feed on the undersides of leaves. Control by spraying upper and lower leaf surfaces with insecticidal soap. 

Oak. See Quercus Oak lace bugs, 194-95 Oak will, 194,395,395 Obliquebanded leafrollers,311,311 Ocimum basilicum. See Basil Oil sprays, 347,479-80 Okra, 154-55... 

Tingidae. See Lace bugs Tip blight, Pinus and, 183,184 Toads, as beneficials, 8,453 Tobacco, flowering. See Nicotiana Tobacco budworms, viral pathogens for, 461... 

Haplophytine (183), (Fig. 8), a polycyclic indole alkaloid, was first isolated by Snyder and coworkers in 1952, and identified as the principle bioactive component of the wild Mexican flower Haplophyton cimicidum A.D.C. (Apocynaceae) [72-77]. Haplophytine is of comparable toxicity to several widely used insecticides, and it was found to be toxic to a wide range of insects including European com borers, Mexican bean beetle larvae, Colorado potato beetle larvae and adults, grasshoppers, egg-plant lace bugs, and codling moths [75]. 

The 6-hydroxy compounds 3 (R=saturated or unsaturatcd C.. or chains) became of interest when they were identified as the major componi ts of tal exudates of immature lace bugs of the genus Corythucha (12) We recently completed the first synthesis of this class of compounds QQ) this work will be discussed in more detail elsewhere in this volume, but one of its key features included converting die easily available 2 to its dihydrobenzisoxazolone derivative 8. This procedure tied up two of the three oxygens of 2, circumventing competitive enolizations and insuring regioselectivity in the hydroxylation to 9, which was in turn converted, via 10, to 3. (Scheme 1). 

We recently identified 2,6-(dihydroxy)undecanophenone 28 from the andromeda lace bug Stephanitis takeyai (XQ, and our interest in this compound was stimulated when it was found to possess high prostaglandin synthase inhibition activity (12). Although 2,6-dihydroxyacetophenone homologs like 28 are not particularly complicated molecdes, there is no really simple general method for their synthesis. 2,6-Dimethoxybenzaldehyde and 2,6-dimethoxybenzoic acid are commercially available as potential precursors, but the former is expensive and in any event the vigorous conditions required for removal of the methoxyl groups make... 

A family of seemingly defenseless insects, commonly known as lace bugs, possess conical shaped exoskeletal processes in the nymph stage which are covert with secreted microdroplets of clear viscous fluid. We here describe (A) the isolation and identification of 3,6-dihydroxy-2-[l-oxo-10(E)-tetradecenyl]-cyclohex-2-en-l-one ftom the fluid secreted by Corythucha ciliata the sycamore lace bug, and (B) the synthesis of a variety of members of this novel class of compounds. 

Microscopic examination of these apparently defenseless insects reveals protruding conical shaped exoskeletal processes which have secretory setae supporting microdroplets of clear, relatively non-volatile fluid (2). Our objectives were to isolate, iden y, syndiesize, and bioassay components from the secreted microdroplets. Although to date we have been unable to unambiguously demonstrate specific defensive functions for the identified microdroplet components, our efforts to define their function(s) continue. This chapter reviews some of our work to date on the identification and synthesis of compounds from immature lace bugs, particularly of the genus Corythucha. 

In like manner, microdroplets from the rhododendron lace bug, Stephanitis rhododendri (Horvath), were shown (4) to contain 2,6-dihydroxyphenyl-r, 3 -diketones 3 (R = CUH. r, CqH.q, lesser amounts of the... 

We next turned our attention to the genus Corythuchay sj ifically C. ciliatay the sycamore lace bug. Preliminary GC-MS examination of microdroplets secreted by C. ciliata indicated the presence of six compounds, a major component (53%) and five minor. None of the six components yield mass spectra resembling those of compounds isolated from the Stephanitis nymphs. Additionally, comparison of the mass spectra of compounds from C. ciliata to spectra within our instrument resident mass spectral data system provided no real clues as to structures or partial structures. 

We have not thus far attempted to synthesize 11 with a specific absolute configuration at carbon 6. The paucity of compounds isolated fix>m lace bugs has prevented determination of the configuration at that site. Additionally, a bioassay to differentiate between isomers is not yet available. 

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