Growth regulators resistance

Quarrie, S.A. (1984). Abscisic acid and drought resistance in crop plants, British Plant Growth Regulator Group News, 1, 1-15. 

The effect of these resistances has been to drive chemical control from one insecticide to the next. In most parts of the Nile delta the cotton leafworms can still be controlled by some OP compound, such as chlorpyrifos, supplemented where necessary with the insect growth regulator Dimilin. But in southern Texas, Mexico, Nicaragua and Peru the multiple resistances of the tobacco budworm, and to a less extreme degree of H. zea and Spodoptera sunia, have made even 20 insecticide applications a season quite worthless, and indeed there is less damage to the cotton if no chemicals are applied at all. The only materials that can be relied upon to kill these multiresistant H. viresoens are the dichlorovinyl pyrethroid NRDC-143 and the Heliothis nuclear polyhedrosis virus. 

The pest mosquito Aedes nigromacul Ls of the vast San Joaquin valley of California went resistant to organochlorines by 1951, to parathion by 1960, to fenthion by 1965, and to chlorpyrifos (Dursban) by 1970. At present reliance is placed on larvicidal oils, the juvenile-hormone mimic methoprene (Altosid) and the insect growth regulator diflubenzuron (Dimilin), — and on better management of surplus irrigation water. Residual sprays for housefly control, at first so spectacular with the organochlorines, had to move into the OP compounds, which were then knocked out in... 

The multiresistant strains now extant also show a certain cross-tolerance, but not resistance, to the third-generation insecticides such as the juvenile-hormone mimics and other so-called insect growth regulators, as was found in strains of the housefly, flour beetle and tobacco budworm. Resistance to the JH mimic methoprene and Monsanto-585 has been induced by laboratory selection of Culex taxsalis (28) and Culex pipiens (29), and to Monsanto-585 in Culex quinquefasstatus (30). Whatever insect or IGR is chosen, the result of exposure to selective doses in successive generations is usually the development of resistance, repeating our previous experience with chemosterilants, and the... 

Alterations of Physiology. Susceptible plant species or cultivars may be rendered resistant to disease by so altering their physiology, e.g., hormonal balances, ion fluxes, constitutive secondary metabolism, or respiratory rates, as to render them unfit or hostile environments for pathogen development, i.e., to make them non-hosts. This could be accomplished, for example, by the use of growth regulators or breeding. 

Xenoblotics can alter various metabolic pathways In plants. Chemical alteration of phenolic compounds for agricultural purposes has been suggested to have potential (130. 131). Since several major plant enzymes of secondary metabolism are Involved In resistance to pathogens, alteration of secondary metabolism could Influence disease development. Herbicides, plant growth regulators (synthetic and natural), and enzyme Inhibitors such as those presented for PAL (Fig. 

Fritz G, Schroeder P, Aktories K (1995) Isolation and characterization of a Clostridium botulinum C2 toxin-resistant cell line Evidence for possible involvement of the cellular C2II receptor in growth regulation. In Infect Immun. 63 2334-40... 

The effects of lAA chloro-derivatives on the growth and the alkaloid production are presented in Fig. (36). Both lAA chloro-derivatives, 4-Cl-IAA and 5,6-Cl2-IAA, enhanced the growth of the roots compared with lAA at low concentrations. The optimum concentrations for alkaloid production were 0.1 mg/1 for 4-Cl-IAA and 0.01 mg/1 for 5,6-Cl2-IAA. The culture with 4-Cl-IAA (0.1 mg/1) or 5,6-Cl2-IAA (0.01 mg/1) resulted in a decrease of scopolamine and in a slight increase of hyoscyamine yield as compared with lAA, Figs. (35) and (36). It is known that 4-Cl-IAA and 5,6-Cl2-IAA are resistant to peroxidase decomposition [56] and the results indicate that they exert their effects at much lower concentrations than lAA. Thus they may be useful plant growth regulators for tropane alkaloid production in root cultures. 

Alar is used as a translocated plant growth regulator. It reduces internode elongation induces heat, drought, and frost resistance and produces darker foliage and stronger stems. It also produces earlier and multiple flowers and fruits. A spray is often applied at the rate of 1500-10 000 ppm. It is systemic (i.e., it is taken up by the fruit). Its residues cannot be washed off or removed by peeling. Use of alar in apples caused environmental concern a few years ago it has now been banned in the United States. 

Jlurowili. A.R. and Ishaaya. I. (1994). Managing resistance (o insect growth regulators in the sweetpotato whiteflv (Homoptera Aleyrodidae). J. Eton. Entomoi 87, 86(5-871. 

Ishaaya, 1. arid Horowitz, A.R. (1995). Pyriproxifen. a novel insect growth regulator for controlling white flies mechanisms and resistance management. Pesric. Sti. 43. 227-232. 

Functionally, pyrethroids are a group of insect growth regulators that act as neurotoxins resisting the development of insect larvae. They are especially effective against insects that are destructive in the adult stage. They are considered non-toxic to animals and humans. Pyrethrum consists of dried flower heads of chrysanthemum. The plant is a native of Dalmatia (Yugoslavia-Balkans) and is now widely cultivated in Kenya, East Central Africa, Japan, Brazil, Ecuador, and India. 

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