Herbivores

This book provides an overview of the current knowledge of herbivory. This book contains chapters from a wide variety of topics that fall into the following broad sections: (I) ""Plant Defense Mechanisms and Herbivore Adaptations,"" (II) ""Herbivory and Food Processing of Grazing Animals,"" and (III) ""Herbivory Effects on Plant Communities."" More specifically, the contributions of this book, written by experts in their respective fields, focus on topics including the chemical plant defense against herbivores as well as herbivore adaptions to plant cyanide defenses, the utilization of biomarkers to study grazing behavior of ruminants, modeling for describing ruminant herbivory, as well as improving grain processing to improve dairy cow performance. Contributions on positive indirect interactions in marine herbivores and algae are included, as is one focusing on herbivory by lizards. These chapters represent recent contributions showing the diversity of ongoing research in this field of study. This book targets a wide audience of general biologists as well as botanists, ecologists, and zoologists including both teachers and students in gaining a better appreciation of this rapidly growing field

Neurophysiological and behavioral responses of gypsy moth larvae to insect repellents: DEET, IR3535, and picaridin.

The interactions between insect repellents and the olfactory system have been widely studied, however relatively little is known about the effects of repellents on the gustatory system of insects. In this study, we show that the gustatory receptor neuron (GRN) located in the medial styloconic sensilla on the maxillary palps of gypsy moth larvae, and known to be sensitive to feeding deterrents, also responds to the insect repellents DEET, IR3535, and picaridin. These repellents did not elicit responses in the lateral styloconic sensilla. Moreover, behavioral studies demonstrated that each repellent deterred feeding. This is the first study to show perception of insect repellents by the gustatory system of a lepidopteran larva and suggests that detection of a range of bitter or aversive compounds may be a broadly conserved feature among insects

Dose response curves (in percent mean consumption) to increasing concentrations of (A) IR3535, (B) picaridin, and (C) DEET.

<p>Asterisks denote the concentration of repellent that significantly decreased feeding relative to the control. Vertical bars represent standard errors.</p

Figure 4

<p>A. Representative traces of responses elicited by the deterrent-sensitive neuron in the medial styloconic sensilla to increasing concentrations of (A) IR3535 (B) Picaridin and (C) DEET. Up-arrowheads represent the response of the large-amplitude deterrent-sensitive neuron.</p

Representative traces of responses elicited from gustatory receptor neurons contained in the medial and lateral styloconic sensilla of <i>Lymantria dispar</i> larvae to various stimuli.

<p>(A) 30 mM KCl (lateral), (B) 10 mM Picaridin (lateral), (C) 30 mM KCl (medial), (D) 10 mM DEET (Medial), (E) 10 mM IR3535 (Medial), (F) 10 mM Picaridin (Medial) (G) a mixture of 10 mM DEET, IR3535, and picaridin, (H) 10 mM caffeine, and (I) a mixture of 10 mM caffeine and 10 mM each of DEET, IR3535, and picaridin. Stimulations of lateral styloconic sensilla with the three repellents, picaridin (shown above in B), IR3535, or DEET did not elicit responses from the gustatory receptor neurons. Up-arrowheads represent the response of the large-amplitude deterrent-sensitive neuron and bars represent the response of the small-amplitude KCl-sensitive neuron.</p

Temporal dynamics of the response of the deterrent-sensitive neuron to 10 mM concentrations of (A) IR3535, (B) picaridin, and (C) DEET.

<p>All repellents elicited a phasic-tonic firing pattern which peaked within the first 100–200 ms following stimulus onset and gradually decreased over the next 800 ms for picaridin and 1000 ms for both DEET and IR3535. A tonic rate of activity (marked by an asterisk) occurred after 1200 ms for picaridin and 1300 ms for DEET and IR3535.</p

Total number of impulses per second produced in the interval 0.05–1.05 s after initial stimulation of the medial styloconic sensilla in <i>L. dispar</i> by the deterrent-sensitive neuron to 10 mM DEET, IR3535, and picaridin compared with the control (30 mM KCl in 10% ethanol).

<p>Different letters represent significant differences between groups. Vertical bars represent standard errors.</p