Oils against pests

The insecticidal efficiency under laboratory conditions of various members of two series of narrow boiling petroleum fractions was determined for adult female California red scale, Aonidiella auranfii (Mask.) and eggs of the citrus red mite, Paratetranychus citri (McG.). Correlations between efficiency and various properties of the fractions such as structural character, molecular weight, and viscosity were observed. These correlations Indicate that conventional spray oils used on citrus in California may contain appreciable amounts of hydrocarbons of low insecticidal activity. The evidence indicates that the insecticidal efficiency of spray oils against citrus insect pests may be considerably improved by proper selection with respect to structural character and molecular size. 

The quick-breaking emulsion concept developed by DeOng et al, (6) in 1927 materially improved the insecticidal efficiency of spray oils against insect pests of citrus. After annoimcement of these results, a large number of proprietary spray oils was placed on the market in California. During the next several years considerable variation in pest control and in damage to citrus orchards occurred with oil sprays. 

Chapman, Pearce, and Avens (4, 20) investigated the relation between chemical composition and insecticidal efficiency of various dormant and foliage spray oils against several common insect pests of deciduous trees, and found it to be positive. They concluded that an oil which is highly paraffinic in character is the most desirable type. Saturated narrow-cut petroleum fractions were used by Pearce, Chapman, and Frear 21) in a study of the influence of molecular weight and structural constitution on the insecticidal efficiency of such oils to eggs of the oriental fruit moth, Grapholitha molesta (Busck). Correlations between efficiency and various properties were compared on the basis of composition. The value of paraffinicity was illustrated, and the importance of other properties was indicated. 

Test methods have been developed for both dormant and summer spray oils to predict accurately the behavior of a given oil, from the viewpoint of both tree or plant response and efficiency against pests. In the earlier days of spray oils, it was difficult to predict the behavior of a given product without actual exhaustive field trials, but by making use of the experience and testing techniques that are now available, spray oils can be selected with definite knowledge as to their behavior under practical usage conditions in the field. 

Pascual Villalobos (2003) found the potential of plant essential oils against stored-product beetle pests. Coriander oil (10 pi) showed activity against the bruchid Callosobruchus maculates, the cereal storage pest. 

Park, I.K., Choi, K.S., Kim, D.H., Choi, I.H., Kim, L.S., Bak, W.C., Choi, J.W. and Shin, S.C. (2006) Fumigant activity of plant essential oils and components from horseradish (Armoracia rusticana), anise (Pimpinella anisum) and garlic (Allium sativum) oils against Lycoriella ingenua (Diptera Sciaridae). Pest Management Science 62(8), 723-728. 

Many other compounds are presendy in use a 1993 database search showed 27 active ingredients in 212 products registered by the U.S. EPA for human use as repellents or feeding depressants, including octyl bicycloheptene dicarboxamide (A/-2-ethylhexylbicyclo[2.2.1]-5-hepten-2,3-dicarboxamide), dipropyl isocinchomeronate (2,5-pyridine dicarboxyhc acid, dipropyl ester), dimethyl phthalate, oil of citroneUa, cedarwood oil, pyrethrins, and pine tar oil (2). Repellent—toxicant or biting depressant systems are available which are reasonably comfortable for the user and can protect completely against a number of pests for an extended period of time (2). 

The literature indicates that oils have been tested against a wide variety of pests. In some cases it is the egg stage against which oils are directed and in other cases the adults or partially mature insects. However, the oil-susceptible species fall into rather distinct biological groups. 

Perhaps the best known of these are the scale insects, family Coccidae (order Homop-tera), represented by the San Jose scale. This species has for many years been a serious pest of deciduous fruits. Another group within this family, the mealy bugs, are also susceptible to oil sprays. Oils used in control of these species are directed against the adults or partially grown forms. 

Petroleum oils are widely used in the treatment of citrus crops in California. They have proved to be the most efficient insecticide per unit of cost for most of the dominant pests of citrus in this area. In an effort to improve oil sprays from the standpoint of both tree safety and insecticidal effectiveness, the research on oil sprays at the University of California Citrus Experiment Station has been intensified. Part of this new effort has involved close cooperation with other laboratories, particularly with the New York State Agricultural Experiment Station at Geneva. The same petroleum fractions and other hydrocarbon compositions were tested simultaneously against citrus and deciduous fruit pests. This coordinated approach has been mutually advantageous, and it is expected that it will lead to an understanding of the fundamental principles involved in the use of hydrocarbon oils as insecticides in general. 

The two species selected for the laboratory studies—California red scale and citrus red mite—are dominant economic pests of citrus in southern California (5). Constant vigilance against infestations of these species is of primary concern to the growth and production of citrus in the area, and petroleum oil sprays are the most important means of control available. 

For killing undesirable plants and for protecting crops against insect pests, it is highly desirable to understand the properties of the petroleum oils which are responsible for plant toxicity. 

Cinnamon oil exhibited fumigant toxicity to adults of Acanthoscelides oblectus and inhibited its reproduction through ovicidal and larvicidal action. Both cinnamaldehyde and cinnamyl alcohol showed ovicidal and larvicidal activity (Roger and Hamraoui, 1994). Cinnamaldehyde possessed antifeedant activity against Ceratitis capitata, a pest causing damage to fruit crops (Moretti et al., 1998). 

On a small scale, there is possibly no less expensive way of protecting stored agricultural produce like grain against predation by pests than using a thin coating of vegetable oil. It must be... 

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