Latex fluids are endowed with insect repellent activity not specifically related to their proteins or volatile substances

Abstract

Latex is an endogenous milky fluid synthesized and accumulated under pressure in a network of laticifer cells. In this study, latices from five plant species were examined for deterrent effect on oviposition of two Coleoptera (Bruchidae) pests. The latex from Euphorbia tirucalli, Calotropis procera and Plumeria rubrae exhibited deterrent activity on oviposition of both Callosobruchus maculatusand Zabrotis subfasciatus beetles. The latex from Cryptostegia grandiflora and Himathantus drasticus were less effective to C. maculatus and Z. subfasciatus oviposition, respectively. Eggs laid on latex-treated seeds were not affected.The emergence and the mean time of development and weight of larvae grown in treated seeds were similar to the controls. The deterrent activity of C. procera and P. rubra was dose and time-dependent for Z. subfasciatus rather than to C. maculatus. The deterrent effect was completely eliminated if the whole latices were fractionated in protein fractions, rubber and small metabolites. Exposing insects to crude latices did not alter ovipostion on untreated seeds. These results suggest that latices possess deterrent activity on insect oviposition mediated by a repellent effect, but that proteins and volatile substances are probably not involved. The repellent-like activity can be considered as a defensive role played by these fluids that relies on the combined action of their components.

Effects of plant latex based anti-termite formulations on Indian white termite <i>Odontotermes obesus</i> (Isoptera: Odontotermitidae) in sub-tropical high infestation areas

“…As literature reveals, plant latexes contain different chemical components which show high anti-feedant, effects on herbivorous insects, when treated with different doses [67] in artificial diets [68]. These candidate molecules which exhibit repellency are monoterpenes, alkaloids, phenolic glycosides, [6] and 2-tridecanone [67]. However, in the present study when fractionated latex samples were used, its toxicity remained intact with the fractions and showed higher insecticidal activity in Odontotermes obesus.…”

“…Thus, proteins, enzymes and allergens protect plants from herbivorous insect attack [64,65], but it is still unclear that repellent activity in plant latexes is due to presence of proteins or volatile substances occur in latex fluid [66]. As literature reveals, plant latexes contain different chemical components which show high anti-feedant, effects on herbivorous insects, when treated with different doses [67] in artificial diets [68]. These candidate molecules which exhibit repellency are monoterpenes, alkaloids, phenolic glycosides, [6] and 2-tridecanone [67].…”

Ethnomedicinal, pharmaceutical and pesticidal uses ofCalotropis procera(Aiton) (Family: Asclepiadaceae)

“…[162] It signifies presence of some distasteful components such as monoterpenes, phenolic glycosides, [163] 2-tridecanone, [162] alkaloids, resins, tannins, saponins, enzymatic proteins and allergens in natural latex that show diverse biological activities. [164] These components make the food distasteful/unpalatable or highly allergic to insects [165] that deter crop pests from feeding on plants. [165] However, no volatile has been isolated from plant latex so far and major toxicants from latex are either proteins or enzymes which lack deterrent activity and act as non-restraint molecules.…”

“…[164] These components make the food distasteful/unpalatable or highly allergic to insects [165] that deter crop pests from feeding on plants. [165] However, no volatile has been isolated from plant latex so far and major toxicants from latex are either proteins or enzymes which lack deterrent activity and act as non-restraint molecules. Thus, deterrent activity may be a consequence of feeding deterrent cum repellent effect, which is possibly operated by some volatile substance from latexes and play multi-defensive role in plants.…”

Sublethal Effects of the Milky Latex of Sodom Apple, Calotropis procera (Alton) on the Growth, development, and some Physiological Aspects of the Greater Wax Moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae)

“…The latex was extracted in the laboratory at the same day of branch collection by cutting the petiole of the fresh leaves and left to flow off in Eppendorf tubes. The latex was gently agitated during collection to overcome the tendency of the coagulation-like effect and was immediately used in the experiments (Ramos et al, 2011).…”