Chemosterilants

Various chemosterilants, which reduce or eliminate reproductive capacity, can be used for insect control as, for example, (12.119). 

Only estimates of the numbers of compounds tested as chemosterilants can be offered. Since 1955, when insect sterility acquired a certain economic potential, close to 10,000 compounds have been screened in various USDA laboratories, primarily in house flies, screwworms, Mexican fruit flies Anastrepha ludens Loew), and boll weevils Anthonomus grandis Bohe-man). Some 600 of these compounds had more or less pronounced streiliz-ing effects, and many were further tested in over 100 species of insects and other organisms. Possibly thousands of additional compounds were screened in other laboratories here and abroad, but an exact count of the active and inactive compounds has not been made. By the end of 1972, more than 1000 insect chemosterilants were described in the scientific literature. This number is more than twice that listed in a survey published by Borkovec (1966). 

A most striking parallel between chemosterilants and mutagens 

Similar chemosterilant (Chang et al., 1964) and mutagenic (Chang and Klassen, 1968 Benes and Sram, 1969 Ninan and Wilson, 1969  

In class 4c, the chemosterilant activity is fairly restricted to triphenyl-tin derivatives, and no mutagenicity data are known for such compounds. There is some controversy regarding the activity of tin chemosterilants in male insects, but in general these compounds are more effective in females than in males. Because a normal function of ovaries depends on a balanced interplay of nutritive, hormonal, and possibly other factors that do not seem to be of similar importance in male gametogenesis, the relationship between sterilizing and mutagenic activity in female chemosterilants is more complex than that in male sterilants. Also, the practical potential of now known tin chemosterilants is limited, and no detailed studies on their metabolism and mode of action have been conducted. Similar considerations apply to boron derivatives (4d), which also are active predominantly in female insects. Nevertheless, because the activity of certain boron compounds has been traced to boric acid (Settepani et al., 1969), a widely used commercial chemical, the implication of possible mutagenic properties in this type of compounds deserves further study. 

From a chemical standpoint, the compounds in classes 4fand 4g constitute an extremely difficult problem for structure-activity studies. Some of them, e.g., the pyrrolizidine alkaloids, have been investigated in great detail (Fishbein et al., 1970, and references therein), and their mutagenic and sterilizing activity is well documented. Others, particularly those that were discovered only recently, are still under investigation, and their full biological evaluation will have to await further development. 

Weirich, G. F., Svoboda, J. A. and Thompson, M. J. (1984) In Biosynthesis, Metabolism and Mode of Action of Invertebrate Hormones. Eds Hoffman, J. and Porchet, M., Springer, Berlin, p. 227. Wellinga, K., Mulder, R. and van Daalen, J. J. (1973a) J. Agric. Food Chem., 21, 348. 

Wellinga, K., Mulder, R. and van Daalen, J. J. (1973b) J. Agric. Food Chem., 21, 993. 

Wiechert, R., Kerb, U., Hocks, P., Furlenmeier, A., Fiirst, A., Langemann, A. and Waldvogel, G. 

In addition to abnormal cellular metabolism one of the characteristics of cancer cells is an increased rate of mitosis, and as a result an increased sensitivity to inhibitors of cell division. Thpreforc, the fact that DNA is the cell component most sensitive to alkylating agents may explain to a certain extent the increased reactivity of cancerous tissues towards these substances. 

On the other hand, from the middle of the 1950s, important results were achieved in the chemotherapy of cancer from treatment with compounds which exert their antimitotic activity as antimetabolites of nucleic acids, folic acid, and purine- and pyrimidine-containing cofactors. 

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A. B. Borkovic, Insect Chemosterilants, Wiley-Interscience, New York, 1966 G. C. LaBreque and C. N. Smith, Principles of Chemosterili cyation, Elsevier,... 

Cinnamyl—sesamol ethers, eg (35), are useful as insect chemosterilants (111). 3,4-Methylenedioxyphenyl-3-halo-2-propynyl ethers (36, X = halogen) are synergists for carbamate insecticides (112). HaloaLkyl or haloalkenyl ethers, eg (37), show acaricidal and insect juvenile hormone activity (113). The first total synthesis of gibbereUic acid was from 2-methoxy-6-aLkoxyethyl-l,4-benzoquinone, a derivative of hydroxyhydroquinone (114). 

Chlorine dioxide gas generated from chlorite has been used as a chemosterilizing agent substitute for ethylene oxide in medical appHcations (174,175). Aqueous foam compositions containing chlorine dioxide have also been developed for the sanitization of hard surfaces (176). 

Dithiazolones, chloro-chlorination, 6, 915 Dithiazolylium salts antifertility activity, 6, 944 as chemosterilants, 6, 944 as herbicides, 6, 944 IR spectra, 6, 907 reduction, 6, 918 Dithiazolylium salts, amino-reactions... 

A number of aldehydes possess antimicrobial properties, including sporicidal activity however, only two, formaldehyde and glutaraldehyde, are used for disinfection. Both these aldehydes are highly effective biocides and their use as chemosterilants reflect this. 

Caffeine is the alkaloid that made coffee fruit and seed so much desired. Caffeine is probably also part of the defense system of the coffee seed, since caffeine has been recognized as an antifungal,149 a selective phytotoxin,150 and a chemosterilant toward certain insects.151... 

Preservative/antimicrobial preservative, antimycotic agent, bacteriophage control agent, chemosterilant/wine maturing agent, disinfection agent... 

Chemosterilant Sterilizes insects or pest vertebrates (birds, rodents)... 

Fluoro-orotic acid was found to be an effective insect chemosterilant. When fed at a 1 per cent concentration (w/w in milk powder) for 24 h, it induced complete and permanent sterility in female adult houseflies (Musca domesticd) [205,206]. Other biological activities of 5-fluoro-orotic acid have been discussed in Part I of this review. 

N. E. Mclndoo, ed., "Plants of Possible Insecticidal Value," USDA, Washington, D.C., 1945 "Materials Evaluated as Insecticides, Repellents and Chemosterilants, Odando and Gainesville, Fla., 1952—1964," USDA, Washington, D.C., 1967. 

Various borate esters are chemosterilants for house flies (51). Tributyl borate, available from Eagle-Picher, Miami, Oklahoma, which is isotopically enriched in boron-10, is being used as a chemical precursor in the synthesis of pharmacologically active boron compounds suitable for boron neutron capture therapy. 

Methylesculetol-6,7-dinicotinate (32) is useful as an antiinflammatory and vasodilator oflow toxicity (101). The synthesis of asarone [5555-15-1] (2,4,5-trimethoxy-l-propenylbenzene), which is used as a tranquilizer, has been patented (102). It occurs in calamus root, Acorns calamus L.y and is a chemosterilant for insects (103). 6,7-Dihydroxycoumarin-4-methylsulfonic acid and its salts are useful in the treatment of capillary permeability and fragility and for protecting oxidizable metabolites and drugs against biooxidation (104). Certain chromones derived from hydroxyhydroquinone, eg (33), and its salts, esters, and amides are valuable in the prophylactic treatment of asthma (105) (see Antiasthmatic agents). 2-Methoxy-6-multiprenyl-l,4-benzoquinones are intermediates in the microbiological synthesis of coenzyme Q compounds (106). 

Genetic Control. Manipulation of the mechanisms of inheritance of the insect pest populations has occurred most successfully through the mass release of sterilized males, but a variety of other techniques have been studied, including the environmental use of chemosterilants and the mass introduction of deleterious mutations, eg, conditional lethals and chromosomal translocations (58 ndash 60) (see GENETIC ENGINEERING). 

The Pesticide Index (ref. 14) lists the following categories of pesticides acaricides, attractants, chemosterilants, defoliants, fungicides, herbicides, insecticides, molluscicides, nematicides, plant regulators, repellents, and rodenticides. Listings are in alphabetical order with structural and molecular formulae for single chemical entities. Other data include CAS nomenclature and number Wiswesser Line Notation LD-50 and test animal data when available physical appearance and safety information. Also provided are a CAS nomenclature index separate molecular (line) formulae of chemicals identified by their common names a separate section of Wiswesser line notations, also with common names an appendix of manufacturers, and an appendix of recent publications dealing with pesticide names. 

Other plant-feeding insects, such as the cabbage looper, have piled one resistance upon another, so that we must look to pheromones and chemosterilants for their control. The western corn rootworm has now joined the onion maggot in going OP-resistant. Resistance problems on pests of rice in Japan are becoming as severe as those on cotton in the Americas. 

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... 

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