Insect interactions with plants

A number of different stresses can elicit inducible compounds important in insect interactions with plants. Some of these compounds appear to attract insects to a plant in distress, such as the southern pine beetle, Dendroctonus frontalis, to Pinus spp. Other compounds appear to prevent attack [22]. Ozone decreases soybean resistance to insect herbivory and overrides induced resistance [Lin, H.C. Kogan, M. Endress, A.G., Environ. Ento. 1990, in press.]. This might be due to a diversion of phenolics into coumestrol instead of more toxic compounds such as glyceollin. 

The sugarcane rootstalk borer weevil is attracted to aggregate by food, others of its kind, and by their frass.161 If the pheromones involved can be identified, they can be used in traps. Insects interact with the terpenes in plants in a variety of ways.162 The insect may find the host plant in this way, either to eat it, or to lay eggs in it. Terpenes such as pulegone (11.34),163 thujone, camphor, and citronellal repel insects (11.35). Linalool has been used as an insecticide on house plants. 

This chapter describes the application and development of trace gas detection based on PTR-MS within life sciences. The chapter begins with a short overview about the ion chemistry that is used in these mass spectrometer systems to sensitively measure trace gases. The overview is followed by the experimental description of the system, including practical aspects such as how to perform a calibration or the use of natural isotopic ratios to gain some information about the identity of the detected compounds. The main part of the chapter deals with applications and measurements performed with PTR-MS to study processes inside plants, fruit, bacteria, and insects interactions between plants and pathogens and also as a tool for human health research. 

Hartmann T, Ober D (2000) Biosynthesis and Metabolism of Pyrrolizidine Alkaloids in Plants and Specialized Insect Herbivores. 209. 207-243 Haseley SR, Kamerling JP, Vliegenthart JFG (2002) Unravelling Carbohydrate Interactions with Biosensors Using Surface Plasmon Resonance (SPR) Detection. 218 93-114... 

One additional factor that comes into play in the overall chemistry of the communication system relates to chemical signals from host plants that can override the photoperiodic control of phermone production. With the com earworm, it was found that a volatile chemical signal from com silk, probably ethylene, was required by wild insects for stimulation of pheromone production (33). This signal probably interacts with controls on the photoperiodic release of PBAN. 

Before we can predict the response of a plant variety to a specific pollutant or group of pollutants, we must understand the following factors genetic variability (both between and within species), climatic and edaphic factors, interactions with other pollutants, interactions with biotic pathogens and insects, and the growth and physiologic age of susceptible plant tissue. The overall conceptualization of relationships between pollutant exposure and ultimate effects is shown simplistically (Figure 11-1) in an adaptation from van Haut and Stratmann. ... 

It is possible that these ecoregulatory enzymes, used by the insect to inhibit targeted plant toxlficatlon systems, may themselves be the principal target of the production of tannins by plants. The discovery of other examples of secondary chemical interactions with enzymes dedicated to the regulation of toxifica-tion and detoxification mechanisms may be expected as our knowledge of chemically mediated plant-insect interaction expands. 

As many of the same types of diterpenes play an active role in the resistance of other plants to insect attack (see above), it is interesting to investigate the role of diterpenes in Solidago and its interactions with insects. Solidago has the advantage that the behavior and the ecology of many of the associated insects are well known (80). 

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