The effect of varying alkaloid concentrations on the feeding behavior of gypsy moth larvae, Lymantria dispar (L.) (Lepidoptera: Lymantriidae)

Abstract

Nine alkaloids (acridine, aristolochic acid, atropine, berberine, caffeine, nicotine, scopolamine, sparteine, and strychnine) were evaluated as feeding deterrents for gypsy moth larvae (Lymantria dispar (L.); Lepidoptera: Lymantriidae). Our aim was to determine and compare the taste threshold concentrations, as well as the ED 50 values, of the nine alkaloids to determine their potency as feeding deterrents. The alkaloids were applied to disks cut from red oak leaves (Quercus rubra) (L.), a plant species highly favored by larvae of this polyphagous insect species. We used two-choice feeding bioassays to test a broad range of biologically relevant alkaloid concentrations spanning five logarithmetic steps. We observed increasing feeding deterrent responses for all the alkaloids tested and found that the alkaloids tested exhibited different deterrency threshold concentrations ranging from 0.1 mM to 10 mM. In conclusion, it appears that this generalist insect species bears a relatively high sensitivity to these alkaloids, which confirms behavioral observations that it avoids foliage containing alkaloids. Berberine and aristolochic acid were found to have the lowest ED 50 values and were the most potent antifeedants.

Bumblebees are not deterred by ecologically relevant concentrations of nectar toxins

“…Other insect taxa have greater gustatory acuity for these compounds; fruit flies, for example, have deterrence thresholds for caffeine and quinine that are 10-100 times lower than those of bees (Sellier et al, 2011). Similarly, gypsy moth larvae (Lymantria dispar) are deterred by caffeine at levels 100 times lower than bees (Shields et al, 2008).…”

Role of the phloem in the biochemistry and ecophysiology of benzylisoquinoline alkaloid metabolism

“…Several structural subgroups have been implicated, including protoberberine, benzophenanthridine, protopine, aporphine, bisbenzylisoquinoline, pthalideisoquinoline, and morphinan alkaloids (Table 1). For example, berberine exhibits potent anti-herbivory activity toward a variety of insects including gypsy moth larvae ( Lymantria dispar ) (Shields et al, 2008), fourth instar larvae of fall webworms ( Hyphantria cunea ), adult Alder leaf beetles ( Agelastica coerulea ) (Park et al, 2000) and fruit flies ( Drosophila melongaster ) (Sellier et al, 2011). Coupled with reduced larval growth and survival rates among generalist pests (Krug and Proksch, 1993), such activity has prompted consideration of berberine as a commercial insecticide (Shields et al, 2008).…”

“…For example, berberine exhibits potent anti-herbivory activity toward a variety of insects including gypsy moth larvae ( Lymantria dispar ) (Shields et al, 2008), fourth instar larvae of fall webworms ( Hyphantria cunea ), adult Alder leaf beetles ( Agelastica coerulea ) (Park et al, 2000) and fruit flies ( Drosophila melongaster ) (Sellier et al, 2011). Coupled with reduced larval growth and survival rates among generalist pests (Krug and Proksch, 1993), such activity has prompted consideration of berberine as a commercial insecticide (Shields et al, 2008). Quaternary ammonium salts of certain protoberberine and benzophenanthridine (e.g., sanguinarine and chelerythrine) alkaloids also show antifungal and antibacterial activities toward economically important plant pathogens (Liu et al, 2009).…”

Larvicidal activity of synthetic tropane alkaloids against Ascia monuste orseis (Lepidoptera: Pieridae)

“…Compounds such as carbaryl, methomyl, carbofuran and methiocarb are among the carbamate insecticides commercially registered. The natural products cocaine, scopolamine and atropine are examples of tropane alkaloids that exhibit insecticidal activity. It is worth pointing out that the scopolamine analogue 8 , lacking the carbamate group, had some insecticidal activity.…”