Insecticidal Activity of Caffeine Aqueous Solutions and Caffeine Oleate Emulsions against Drosophila melanogaster and Hypothenemus hampei

Abstract

The bioactivity of caffeine aqueous solutions (0.20-2.00 wt %) and caffeine oleate emulsions (20 vol % oil, 2.00 wt % surfactant, 0.04 wt % caffeine, 0.05 wt % oleic acid) was assessed against two biological models: Drosophila melanogaster and Hypothenemus hampei. The caffeine aqueous solutions showed no insecticidal activity, whereas caffeine oleate emulsions had high bioactivity against both D. melanogaster and H. hampei. By preparing the caffeine oleate emulsions with anionic surfactants (i.e., sodium lauryl sulfate, sodium laureate, and sodium oleate), we obtained a lethal time 50 (LT50) of 23 min. In the case of caffeine oleate emulsions prepared with nonionic surfactants (i.e., Tween 20 and Tween 80), a LT50 of approximately 17 min was observed. The high bioactivity of the caffeine oleate emulsion against H. hampei opens the possibility of using this insecticide formulation as an effective way to control this pest that greatly affects coffee plantations around the world.

NMR Reinvestigation of the Caffeine–Chlorogenate Complex in Aqueous Solution and in Coffee Brews

“…The molecular structure of caffeine-oleate complex in aqueous systems has been recently reported. 28 In the present work, espresso coffee brews have been characterized under experimental conditions close to those of Tavares and Ferreira. 27 In Figure 4, the typical 1 H-NMR spectrum of espresso coffee brew is reported.…”

“…The hydroxyl in position 4′ on chlorogenic acid might interact with the carbonyl in position 2 on caffeine, possibly through a bridging water molecule. Based on the work by Araque et al 28 on caffeine interacting with oleate, we looked for a possible contact between the carboxylate of the quinic moiety with the imidazole hydrogen of caffeine. Although the two groups can come close up to 0.34 nm, we believe this interaction must be excluded in our complex as we should have found NOEs between H 12 and H 8 of caffeine and H 2 protons of the quinic portion.…”

Long-Term Functional Side-Effects of Stimulants and Sedatives in Drosophila melanogaster

“…In addition, caffeine was clearly detrimental to survival. It was quite surprising to us to find that caffeine was such a toxic substance, at least at dose-levels that we estimate to correspond to normal human intake, in that caffeine has been tested for insecticidal activity and none has been found [27].…”

Adulticidal Activity of Coffee Essential Oils against Two Fruit Fly Species (Tephritidae) under Laboratory Conditions

“…The coffee oil (unsaponifiable matter) consists of various compounds in free form such as diterpenes, alcohols, cafestol, and caveol [29], and those substances are responsible for the important biological effects of coffee oil as a fungicide [30] and an insecticide. Caffeine showed high efficacy as an insecticide against coffee berry borer Hypothenemus hampei [31] and demonstrated a larvicidal effect on Aedes aegypti [32].…”