Ovicidal

Use pattern Hexythiazox is a thiazolidinone acaricide which has ovicidal, larvicidal and nymphicidal activities against many kinds of phytophagous mites infesting pome fruits, stone fruits, citrus, vegetables and other food crops. On these mites, hexythiazox works by both contact and stomach action... 

Action Insecticide, larvicide, ovicide insect growth regulator acting by interference with deposition of insect chitin... 

Uses Dormant ovicidal spray for fruit trees (highly phototoxic and cannot be used successfully on actively growing plants) selective herbicide and insecticide. 

Optimization of biological properties in a series of miticidal and mite ovicidal 2-aryl-l,3-cycloalkanediones, Ia,b, and enol esters, II, was achieved through analog synthesis and testing supported by the development of quantitative structure/ activity trends during the course of the project. QSAR equations developed during an initial phase provided the basis for both... 

Objectives. Given an extensive databank of more than 200 compounds, many of which had excellent miticidal and ovicidal potency and the opportunity to continue the synthesis of permutations in pursuit of even better compounds (but with the probability of encountering more of the same), what did we hope to achieve by multidimensional analysis at this stage of the project Answers... 

The drug affects the scolex and proximal segments of the cestodes, resulting in detachment of the scolex from the intestinal wall and eventual evacuation of the cestodes from the intestine by the normal peristaltic action of the host s bowel. Because niclosamide is not absorbed from the intestinal tract, high concentrations can be achieved in the intestinal lumen. The drug is not ovicidal. 

Several nematicidal acetylenic compounds have been isolated. Most are from the Asteraceae (127). Recently isolated are (8R,9R, 10S)-9,10-epoxyheptadec-16-ene-4,6-diyne-8-ol and other compounds from Cirsium. iaponicum (128,129). 1-Phenylhepta-l,3,5-triyne and 2-phehyl-5-(1 -jjropynyl)-thiopene, from Coreopsis lanceolata and cis-dehydromatricaria ester from Soli dago altissima have been shown to be fly ovicidal substances (130,131). 

In the case of oil sprays a direct relationship has been shown by Cressman and Daw-sey (7) between the amount of oil deposited and insect kill or control. A similar relationship has been shown by Chapman ei al (4) using oil as an ovicide in control of the fruit tree leaf roller. This relationship appears to hold regardless of the emulsifier used. The literature indicates that much attention has been given to the infiuence of emulsifiers on differences in effectiveness of oils. In many cases differences in effectiveness are attributed directly to the influence of the emulsifier. In spite of the various ways in which effects of emulsifiers have been interpreted, it appears that the basic influence of the emulsifier is on amount of oil deposited. 

Ovicide action. Theories on the mode of action of ovicides suggested by Hoskins (12) and Martin (13) are summarized as follows ... 

Insecticide Action. The mode of action involved in the toxic effect of oils on hatched forms is no better understood than in the case of ovicides. Several theories which have been advanced are siunmarized by Shepard 19) as follows ... 

As in the case of mode of action of ovicides, much work remains to be done before the mechanism whereby oils kill insects is clearly understood. 

Figures 3 and 4 indicate that the relations of composition and molecular size to the efficiency of petroleum oils against eggs of the citrus r mite are of the same type, with essentially the same critical values, as those foimd by Pearce, Chapman, and Frear (ff) for eggs of the oriental fruit moth. The ovicidal efficiency is nearly constant above a molecular weight of 340 and falls off very rapidly to indeterminate amounts below this level.

Additional studies were made of the oil as an insecticide and ovicide, when applied as an emulsion. In all cases the isoparaffinic fraction was solubilized by the addition of Triton B-1956, a nonionic phthalic glycerol alkyd resin. The emulsions were applied to the point of mnoff (200 to 400 gallons per acre). The results of these tests are shown in Table I. 

The isoparaffinic fraction employed in these studies is promising as an insecticide and ovicide—for use alone or in combination with other insecticides. 

Benzimidazoles are thought to act against nematodes by inhibiting microtubule synthesis. Albendazole also has larvicidal effects in hydatid disease, cysticercosis, ascariasis, and hookworm infection and ovicidal effects in ascariasis, ancylostomiasis, and trichuriasis. 

The mechanism of action of thiabendazole is probably the same as that of other benzimidazoles (see above). The drug has ovicidal effects against some parasites. 

Neem extracts, pure constituents (i.e. azadirachtin) and formulated products showed positive results against Tetranichus mites [279-283]. Less polar extracts were considerably more toxic than polar ones or cold-pressed neem oil or commercial neem oil, and reduced the fecundity of the mites on treated plants and the survival of nymphs hatched from treated eggs application of pentane extract or neem oil in sublethal concentrations, caused growth disrupting effects on the nymphal stages and ovicidal effects. Quantification of the insecticidal substance azadirachtin in the extracts revealed that this compound was not the most active principle against the mites [284]. 

Insecticidal activity is shown by a number of oxygen heterocycles. Xanthone is an ovicide for the codling moth and the naturally occurring coumarin mammein (713) shows insecticidal properties. 

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