Resistance to insects

One of these proposed functions is to protect a plant from attack by biological agencies, particularly phytophagous insects. In support of this view is the now classical work of Feeny who showed that a decreasing tendency for lepidopterous larvae to feed on oak leaves as they matured could be correlated with a 10-fold increase in tannin concentration between young and mature leaves (30). Moreover, both Feeny and Chan and co-workers (69) showed that such larvae exhibited growth inhibition when their diet included condensed tannin. 

At least five mechanisms have been suggested on how condensed tannins might act as antibiotic agents against insects these include reduction in the avail- 

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Bugs coca is amazingly resistant to insects and mites. Mealy bugs are the worst offenders. These may be removed with a forceps or cotton swab dipped in 50-70% alcohol. Keep infested plants in quarantine. Malathion may be used as a last resort, but then leaves cannot be used until the next flush (of leaves). 

Tg = 70-85 °C, higher than polyolefins because polar C—Cl bond gives dipole-dipole intermolecular attractions Low crystallinity Good impact strength Good chemical resistance Resistant to insects and fungi Non-flammable... 

Resistance of plants to herbivorous animals is determined in many cases by the presence in plant tissues of secondary metabolites that may cause feeding deterrence or toxocity to the animal. Insects cause damage to cereals, decreasing grain production. Development of varieties resistant to insects is then desirable for improving cereal productivity. 

Resistant hirsutum race stocks Texas No. 254 and 810 also are deficient of bisabolene and B-bisabolol stocks 810, 1055, and 1123 have greatly increased caryophyllene oxide contents and stock 953 has greatly reduced concentrations of caryophyl 1 ene, caryophyl 1 ene oxide, and humulene (Table II). It is tempting to attribute the known increased resistance to insects in the Texas race stocks to the changes in volatile profiles, but this hypothesis remains to be proven. 

Figure 3. Cuticular Diterpenoids—Duvanes and Labdanes important in host-plant resistance to insects.

First field testing of transgenic plants resistant to insects, bacteria and viruses... 

Hedin, P.A. et al.. Multiple factors in cotton contributing to resistance to the tobacco budworm Heliothis virescens F., in Plant Resistance to Insects, Heden, P.A., Ed., American Chemical Society, Washington, 1983, 347. 

Hedin, P.A. and Waage, S.K., Roles of flavonoids in plant resistance to insects, in Plant Flavonoids in Biology and Medicine Biochemical, Pharmacological and Structure Activity Relationship, Cody, V., Middleton, E., and Harbome, J.B., Eds., Alan Liss, New York, 1986, 87. 

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