Anti-insect activity

Notwithstanding this, their use in plant protection has so far brought modest results. This is due mainly to their narrow range of anti-insect activity, the necessity of critical timing in their application, insufficient persistence, lack of immediate action, and the possibility of reinvading population. 

Continuing with the study of bioactive constituents of members of the Lauraceae family, we conducted an investigation of the anti-insect activity of Lauraceae species endemic to Japan. 

Despite interest in the anti-microbial and anti-insect activities of flavonoid C-glycosides (e.g. from maize), and the potential therapeutic value of isoflavone C-glycosides such as genis-tein 8-C-glucoside (Fig. 6) or puerarin from Pueraria lobata, no plant gene encoding a C-glycosyltransferase has yet been cloned. 

Cyanogenic lipids (cyanolipids) occur together with conventional triacylglycerols in the seeds of many plants of the soapberry family (Sapindaceae) in certain cases they represent more than 50% ofthe seed oil. Members of this family have been widely studied for their pharmacological (antioxidant, anti-inflammatory and anti-diabetic properties) and anti-insect activities, and many species have economically valuable tropical fruits and wood. Some cyanogenic lipids also occur in plants of the Hippocastaneaceae and Boraginaceae families, which are not used for human consumption. 

Lord and Potter1 have claimed that it is important not to generalize the known anti-cholinesterase activity of organo-phosphorus insecticides in mammals to account for their action in insects. They could find no specific cholinesterase in two species of insect, but there was a general esterase inhibited by the insecticides. 

The secondary metabolites of the endophytic fungi associated with dicotyledonous plants (dicots) are chemically diverse (Table 1). There is an equal diversity in the activities of these compounds, including antibacterial, antifungal, nematicidal, phytotoxic, cytotoxic, antineoplastic, anti-insectant, anti-herbivory, and a variety of other activities. The compounds isolated, structurally elucidated, and explored biologically in the short time since previous reviews continue to display that same wide array of chemical and biological diversity. 

The diterpenoids of Isodon (Labiatae) species have been reviewed. The presence of an a-methylenecyclopentanone moiety in these diterpenoids is important for their anti-tumour and anti-bacterial activity. " Inflexin (79) is a cytotoxin and insect antifeedant which has been isolated from Isodon inflexus. Isodomedin (80) is another member of this series, isolated from /. shikokianus, which shows this type of biological activity. Its structure was assigned on the basis of its H and C n.m.r. spectra and on an interrelationship with kamebanin (81), isolated from /. kameba. 

Iridoids have shown a broad range of biological activities, such as an antibacterial, antifungal, anti-inflammatory, antitumoral, hepatoprotective, cardioprotective, antioxidative, antiprotozoal and anti-insect properties [13,14,15,16,17,18,19]. In vitro activities inhibiting the hepatitis C virus, the differentiation of the adipocyte, and PPARa activation activities have been also described [20, 21]. 

Many triterpenes also have anti herbivore activity. In general, those which are highly oxygenated seem to be more active in this regard M). The role of cardiac glycosides, insects and their predators has been reviewed (91-94). A number of metabolically altered triterpenes from the Rutaceae, Meliaceae and Simaroubaceae are antifeedants. Extracts of neem tree seeds (Azadirachta indica. Meliaceae) were shown to be repellent to a number of insects when applied to various crop plants at low concentrations. The probable active compound is tetranortriter-pene, azadirachtin (9 ). This compound from the leaves and fruits... 

The CBs used as pesticides are N-substituted esters of carbamic acid. CBs developed in the 1950s as insect repellents were found to have insecticidal activity, leading to the development of the napthyl CBs with high anti-ChE activity and selective toxicity against insects. One example is carbaryl it is widely used because of its low toxicity to mammals and its degradability. Aldicarb, a plant systemic, is more toxic than carbaryl. A few years ago aldicarb was associated with a July 4th holiday incident when West Coast residents complained of anticholinergic symptoms after eating aldicarb-contaminated watermelon. 

According to Ramadan and cowoikers (36), aqueous extract of the baobab fruit pulp produces a marked anti-inflammation activity. The effect was comparable to that induced by standard phenylbutazone (15 mg/kg). This antiinflammatory effect may be due to the presence of sterols, saponins and triterpenes in the aqueous extract. The extract also shows a marked antipyretic activity (36). The antipyretic activity of the extract resembles that normally induced by standard dose of administered acetylsalicyhc acid (ASA) in hyperthermic rats. Leaves are applied locally for a variety of inflammatoiy conditions, insect bites and guinea worm sores (8). Anti-pyretic activity has been reported (36). 

The anti-feedant activity of these compounds has been tested against various insects, including food storage pests such as Tribolium confusum. 

Usnic acid (7.53)—a highly biologically active dibenzofuran—is a phenol oxidation product of an acylphlorogludnol. It is produced by numerous lichens, including several Usnea species. Apart from its antibiotic and anti-leukemic activity, it has insect anti-feedant activity. Its presence may account for the observation that many lichens are resistant to serious insect attack. 

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