Binary mixtures of feeding deterrents mitigate the decrease in feeding deterrent response to antifeedants following prolonged exposure in the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae)

Abstract

The effect of rearing larvae of Trichoplusia ni on individual feeding deterrents or on binary mixtures of deterrents on their subsequent gustatory sensitivity was measured in paired choice leaf disc bioassays. Our working hypothesis was that mixtures of antifeedants (pure allelochemicals) would mitigate decreased feeding deterrent response following prolonged exposure in this generalist herbivore. Neonate larvae were reared on cabbage leaves treated with individual feeding deterrents (digitoxin, thymol, toosendanin or xanthotoxin), or with binary mixtures of these until the third instar. Feeding deterrent responses to each antifeedant or mixture was then determined in a leaf disc choice bioassay. All of the mixtures produced additive deterrence when presented to naïve larvae. Larvae reared on individual antifeedants showed a significantly decreased feeding deterrent response (except to digitoxin), whereas larvae reared on binary mixtures of antifeedants did not show a decreased feeding deterrent response to any of them. Such mixtures were synergistic in terms of their feeding deterrence to "experienced" larvae. Our experiment supports the hypothesis (Jermy 1986) that mixtures of deterrents can prevent decreased feeding deterrent response following prolonged exposure, and provides one explanation for the multiplicity of chemical defenses found in many plants.

Experience‐altered oviposition responses to a neem‐based product, Neemix®, by the diamondback moth, Plutella xylostella

“…Various strategies, such as the mixture of several deterrents or a mixture of a deterrent with a toxicant, have been shown to have the potential for mitigating the decrease in feeding deterrent responses to antifeedants by insects 2, 32. These strategies may apply to the development of effective oviposition repellents/deterrents.…”

Diversity of the Volatile Organic Compounds Emitted by 55 Species of Tropical Trees: a Survey in French Guiana

“…A high chemical diversity should help increase the plant's protection against attacks from a wide range of enemies in changing environments (Agrawal and Fishbein 2006;Gershenzon and Dudareva 2007). Moreover, diverse compounds may act synergistically to provide greater toxicity or deterrence (Berenbaum and Neal 1985), or to maintain activity for a longer period of time (Akhtar and Isman 2003). Complex VOC blends also may be involved in making the information sent to parasitoids in tritrophic interactions species-specific (Gershenzon and Dudareva 2007).…”

The role of phenols in the influence of herbal extracts from Salvia officinalis L. and Matricaria chamomilla L. on two-spotted spider mite Tetranychus urticae Koch

“…Crude extracts prepared from various plants can be more effective against pests, as compared to individual compounds, because chemicals may interact synergistically or additively (HAY et al 1994;NELSON & KURSAR 1999;AKHTAR & ISMAN 2003;SAKUNWARIN et al 2004).…”