Neem A Tree for Solving Global Problems (1992) / Chapter Skim
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5 Effects on Insects
5 Effects on Insects
Pages 39-50
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From page 39... ...
Further, the materials used in various tests have often been handled and stored differently, taken from differing parts of the tree, or produced under different environmental conditions. But, for all the uncertainty over details, various neem extracts are known to act on various insects in the following ways: · Disrupting or inhibiting the development of eggs, larvae, or pupae; · Blocking the molting of larvae or nymphs; · Disrupting mating and sexual communication; · Repelling larvae and adults; · Deterring females from laying eggs; 39
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From page 40... ...
INSECTS AFFECTED By 1990, researchers had shown that neem extracts could influence almost 200 insect species. These included many that are resistant to, or inherently difficult to control with, conventional pesticides: sweet potato whitefly, green peach aphid, western floral thrips, diamondback moth, and several leafminers, for instance.
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From page 41... ...
However, once the adult thrips and related pests have taken up residence on the plants themselves, they are less sensitive to neem extracts. Oily formulations have shown some success in exploratory trials (perhaps because the oil coated and suffocated these minute creatures)
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From page 42... ...
Insect Effects Mediterranean fruit fly Oriental fruit fly Face fly Horn fly Whitefly Housefly Sorghum shoot fly Yellow-fever mosquito House mosquito Flea Head lice Spotted cucumber beetle Mexican bean beetle Colorado potato beetle Plea beetle Khapra beetle Confused flour beetle Japanese beetle Red flour beetle American cockroach Bean aphid Rice gall midge Disrupts growth, toxic Arrests pupae development, retards growth, toxic to larvae Retards growth, toxic Repels, retards growth, disrupts growth Repels, retards growth, inhibits feeding Inhibits feeding, disrupts molting, repels Inhibits feeding Kills larvae, disrupts molting Toxic to larvae Retards growth, repels, inhibits feeding, disrupts growth, eggs fail to hatch Kills, very sensitive to neem oil traditional use in Asia Retards growth, inhibits feeding Retards growth, inhibits feeding, disrupts molting Eggs fail to hatch, larvae fail to molt with azadirachtin levels as low as .3 ppm, inhibits feeding Inhibits feeding Inhibits feeding, disrupts molting, toxic to larvae Inhibits feeding, disrupts molting, toxic to larvae Repels, retards growth, inhibits feeding, disrupts growth Inhibits feeding, toxic Reduces fecundity and molts, reduces number of fertile eggs Reduces fecundity, disrupts molting Toxic
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From page 43... ...
EFFECTS ON INSECTS Insect Effects Western thrips Diamondback moth Webbing clothes moth Gypsy moth Corn earworm Pink bollworm Fall armyworm Tobacco budworm Tobacco hornworm Cabbage looper Leafminer Serpentine leafminer Brown planthopper Green leafhopper Migratory locust House cricket Large milkweed bug Mealy bugs Milkweed bug Fire ant Boll weevil Cowpea weevil Rice weevil 43 Retards growth Strongly suppresses larvae and pupae, retards growth, inhibits feeding Inhibits feeding, disrupts molting Retards growth, inhibits feeding, disrupts growth Retards growth, inhibits feeding, disrupts molting Retards growth, inhibits feeding Retards growth, repels adults, inhibits feeding, disrupts molting, toxic to larvae Inhibits feeding Inhibits feeding, disrupts growth, toxic Inhibits feeding Retards growth, inhibits feeding, disrupts molting, toxic High pupal mortality, retards growth, inhibits feeding, disrupts molting, toxic to larvae Inhibits feeding, repellent, disrupts growth, mating failures and sterility Inhibits feeding Stops feeding, converts gregarious nymphs into solitary forms, reduces fitness adults cannot fly Disrupts molting Toxic, disrupts growth Repels, inhibits feeding Difficulty in escaping the "skin" of the last molt, disrupts molting Inhibits feeding, disrupts growth Inhibits feeding Inhibits feeding, toxic Inhibits feeding, disrupts growth, toxic
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From page 44... ...
, it appears that larvae of most lepidopterous pests are highly sensitive to neem. Indeed, it seems likely that armyworms, fruit borers, corn borers, and related pests will become the main targets of neem products in the near future.
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From page 45... ...
Those first approaches used alcoholic extracts and were aimed at disrupting metamorphosis or at stopping adult locusts from feeding on crops. The new approach uses neem oil enriched with azadirachtin to prevent locusts from developing into their migratory swarms.
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From page 46... ...
In this connection, repellency seems of primary importance. For instance, treating jute sacks with neem oil or neem extracts prevents pests in particular, weevils (Sitophilus species)
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From page 47... ...
This extremely serious pest is found worldwide and in some locations is playing havoc with vital crops of leafy vegetables such as cabbage.
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From page 48... ...
This commercial product, now available almost nationwide, is expected to be especially useful against those leafminers that attack horticultural crops. Added to the soil, neem compounds enter the roots and move up into the crop's leaves so that leafminers munching on the leaves get their molting-hormone jammed, and they end up fatally trapped inside their own juvenile skins.
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From page 49... ...
In one test, crushed neem seeds thrown into pools proved nearly as effective at preventing mosquito breeding as methoprene, a rather expensive pesticide that is usually imported in developing countries. Aphids In the Dominican Republic, water extracts of neem seed proved effective against Aphis gossypii on cucumber and okra and against Lipaphis erysimi on cabbage.'3 This was in direct-contact sprays.
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From page 50... ...
The animals readily consumed feed containing 0.1-1 percent ground neem seed. The neem compounds passed through the digestive tract and into the manure where they kept the fly larvae from developing.' Blowflies In Australia neem products have been tested against blowflies on sheep.
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