Pests, catching

Pheromone traps are mechanical devices containing scents that attract a specific insect species. Pheromone traps are available for Japanese beetles and a wide range of other insects. The insects are enticed into the trap by the scent and are unable to get out. These traps attract pests from a considerable distance, but do not immediately catch all the insects they attract. They are best used some distance from the garden to attract the insects away from, not into. 

It is not only drugs that have to be manufactured enantiomerically pure. This simple lactone is the pheromone released by Japanese beetles (Popilia japonica) as a means of communication. The beetles, whose larvae are serious crop pests, are attracted by the pheromone, and synthetic pheromone is marketed as Japonilure to bait beetle traps. Provided the synthetic pheromone is the stereoisomer shown, with the Zdouble bond and the R configuration at the stereogenic centre, only 25 jug per trap catches thousands of beetles. You first met this compound in Chapter 32, where we pointed out that double bond stereocontrol was important since the -isomer of the pheromone is virtually useless as a bait (it retains only about 10% of the activity). Even more important is control over the configuration at the chiral centre, because the S-enantiomer of the pheromone is not only inactive in attracting the beetles, but acts as a powerful inhibitor of the R-enantiomer—even 1% S-enantiomer in a sample of pheromone destroys the activity. 

Small-scale field trials with fully stabilised micro-encapsulated formulations were carried out in Egypt during 1980 on two cotton pests - pink bollworm, Peotinophora gossypiella, and the Egyptian cotton leafworm, Spodoptera littoralis. Plots of 10 n x 10m were sprayed with the formulation and there were three replicates of each treatment. A plastic funnel trap (3) baited with synthetic pheromone was positioned at the centre of each plot. The effectiveness and persistence of communication disruption were measured by the reduction in catches of male moths in the traps in the treated plots relative to the catches in similar traps in untreated, control plots. 

Leaves skeletonized. Causes White-marked tussock moths Japanese beetles. Whitemarked tussock moths are V/i" long yellow caterpillar has 4 clumps of white hair on its back, along with 2 tufts of black hair on the head and 1 at the rear. Birds and natural parasites usually keep this pest under control. Tf damage occurs, reduce future populations by scraping the frothy white egg masses off trunks and branches. Band trunks with a sticky coating, such as Tanglefoot, to catch caterpillars as they crawl up the tree. Spray leaves with BTK to control serious infestations. 

Beneficial Effect Mantids catch and devour both pests and beneficial species. They eat virtually any insects they catch. 

Trap size is limited only by the materials on hand, since scientists haven t yet decided exactly what is too big or "too small. Naturally, larger traps will catch more pests. Commercial traps are available in a range of sizes from 3" X 5" and up. Long, narrow, rectangular, or oval shapes may attract the most pests. 

To catch whitcflies and other pests, paint boards yellow (Federal Safety Yellow No. 6.S9 from Rustoleum Company and Saturn Yellow from Uay-Glo Colors are 2 colors most pests find attractive) before applying homemade or commercial sticky coating. 

Protection Offered You can use trap crops to catch a variety of insect pests. Un-... 

Praying mantid Mantis religiosa Any insect they con catch, including beneficial species. Not advisable to release in garden because ot destructive effect on native species. Not effective as control for pest insects. 

The use of pheromones in trap catch data is an important integral part of these forecasting systems and combined with control methods they contribute substantially to insect pest management programs and population monitoring. The use of pheromones in both monitoring and control of pests will eontinue to increase as more research and data become available. 

Bark beetles of the genus Ips are pests which attack pine and spruce trees. They use ipsdienols as aggregation pheromones, Ips confusus emitting the (5)-(-l-)-, and Ips paraconfusus the (.K)-(-)-enantiomer The beetles receive the myrcenes (section 2.2) occurring in conifers with their food and metabolize them to ipsdienols some evidence for de-novo synthesis by the bugs is also reported. In order to catch the beetles, pheromone traps are supplied with both enantiomers of ipsdienol which are produced from (-l-)-verbenone, a constituent of the Spanish verbena oil (section 2.4.3). This terpenone, also available by oxidation of a-pinene, is isomerized to the enantiomers of 2(10)-pinen-4-one via three steps (reduction, protonation, oxidation). After separation, both enantiomers are reduced by lithiumaluminumhydride. Pyrolytic cycloreversion of the resulting diastereomeric 2(10)-pinen-4-ols provides the enantiomers of ipsdienol... 

Baby leaves and herbs are attractive to a wide range of pests especially aphids, leaf miners, caterpillars and slugs. The contamination of the crop with insects is also a commercial issue. Seedling diseases can affect the crops such as Pythium and Rhizoctonia but the main disease is downy mildew which can lead to complete crop loss if untreated. Resistant lines are available for some of the larger volume crops like spinach but downy mildew evolves new strains rapidly and plant breeders are always playing catch up . 

At the present time the first two categories are operational, although more research is needed to relate trap catches to insect populations. Use of pheromones for population suppression by the other techniques is now in the highly promising stage for many pests, and is operational for several we shall consider the promises and problems on a crop-by-crop, insect-by-insect basis. Coverage will be selective and emphasis will be on the more advanced systems and those most familiar to the authors. 

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