PERSPECTIVES AND OVERVIEWThe behavior of insects, and all animals, is governed by interactions amongneurons within their nervous systems. Insecticides have been selected andsometimes designed for their remarkable ability to kill insects. Most attackspecific sites within the insect’s nervous system (59, 63; see section on modesand sites of action). Therefore it is not surprising that insecticides at levelsthat do not lead to mortality can influence behavior. However, there havebeen few detailed studies concerning the potential behavioral effects ofsublethal doses of insecticides.Studies of the behavioral effects of neurotoxicants are important for severalreasons (89). First, detailed observations of the behavioral symptoms poisoned insects will help to elucidate the modes of action of both novel andconventional insecticides. Second, it is clear that almost all insecticidesinterfere with the normally well-orchestrated behavioral patterns of pestinsects and thus might contribute to management of their populations. Animportant related point is that beneficial insects may be adversely affected bythese compounds in a way that is overlooked by current screening procedures.Lastly, selection may favor those insects that respond to insecticides in theenvironment by minimizing their contact with the toxic material; thus thepotential for evolution of behavioral resistance to insecticides is anotherimportant consideration.Insecticides are the cornerstones upon which pest management practices arebased, and are likely to remain so as long as effective and inexpensivechemicals are available. However, many insect-pest management techniques1490066-4 170/88/0101-0149 $02.00Annual Reviews www.annualreviews.org/aronline

Sublethal Effects of Neurotoxic Insecticides on Insect Behavior

Publisher Summary Salivary function is especially interesting in Hemiptera because of the effects the saliva has on the living and surviving organisms, on which many of these insects feed. The saliva of Hemiptera is by no means a simple secretion—in addition to the usual salivary functions of moistening food and mixing it with hydrolytic enzymes before ingestion, the saliva of phytophagous species plays an important physiochemical role during the mechanical penetration of plant tissues by the piercing and sucking mouthparts; in accomplishing this task, the saliva may vary in its chemical composition and physical consistency from one moment to the next. Moreover, deposits of solidifying components of the saliva of many species persist in the food plants, modifying the long term effects of feeding by the insects. This chapter compiles the various types of investigation on salivary functions in the Homoptera and Heteroptera, and suggests profitable lines of future investigation based on analogous functions in different taxonomic groups.

The Saliva of Hemiptera

Publisher Summary This chapter discusses the resistance of plants to insects. Resistance is the ability of a certain variety to produce a larger yield of good quality than other varieties at the same initial level of infestation and under similar environmental conditions. Three basic components or mechanisms are involved in plant resistance. First, plants may be nonpreferred for oviposition, shelter, or food, primarily, because of the lack of or presence of chemical or physical factors. Second, resistant plants may affect the biology of the insect adversely that is called antibiosis. Third, resistant plants may be tolerant, surviving under levels of infestation that would kill or severely injure susceptible plants. Several problems may occur at various stages in the development of any host plant resistance program. Some of these problems include: proper finance, entomological problems, and problems in technique development. Resistance is most often found in off types or exotic wild species, and considerable crossing and selection is required to move the resistant genes into a desirable agronomic background. The greatest use of resistant varieties would undoubtedly be as one component part of pest management system.

Resistance of plants to insects.

The factors responsible for determining the host-plants and feeding sites of aphids, and the various probing activities (the role of the labium, stylet insertion, surface saliva deposition, the behaviour of the aphid, virus transmission) are examined. There is a brief review of stylet structure and movement and the possible sensory nature of these organs, followed by a detailed review of the characteristics of aphid stylet paths in plant tissues. The penetration of epidermis and vascular tissues is treated separately while that within the intermediate tissues is covered in relation to leaves and stems, roots, trees, galls and excised tissue as well as in separate sections on Aphis fabaeScopoli and Myzus persicae (Sulzer). Stylet destinations and behaviour in the sieve tubes are discussed together with general features such as rate and depth of penetration, guidance to the feeding site, effects of tissue hardness and stylet withdrawal. The ingestion rate of plant sap is reviewed and its constitution and importance examined together with the significance of artificial diets. The salivary secretions including sheaths and tracks, their functions and their role in the transference of material between aphid and host are dealt with. The nature of the physical and internal damage resulting from aphid feeding is briefly covered, and also some plant-insect interrelations. The aphid species whose stylets have been examined in plant tissue are listed.

Plant penetration by feeding aphids (Hemiptera, Aphidoidea): a review

Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

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Laccase: Microbial Sources, Production, Purification, and Potential Biotechnological Applications

This reaction was evident primarily as a gustatory response and not as an alighting response. The insects caged on Mudgo had high mortality, a slow growth rate, small body size, and low fecundity. Newly emerged female planthoppers caged on Mudgo had underdeveloped ovaries that contained few mature eggs. PIanthoppers did not exhibit any diMculty in inserting their stylets or reaching the vascular bundEes in Mudgo plants. Still when caged on this host they lost weight and excreted very little heneydew. These results indicated that Mudgo plants either lacked feeding stimuli or

Kazushige Sogawa

Papers

Mechanisms of Brown Planthopper Resistance in Mudgo Variety of Rice (Hemiptera : Delphacidae)

Studies on the Feeding Habits of the Brown Planthopper, Nilaparvata lugens (STÅL) (Hemiptera : Delphacidae) : IV. Probing Stimulant

Correlation between Migratory Flight of Rice Planthoppers and the Low-Level Jet Stream in Kyushu, Southwestern Japan

Studies on the Salivary Glands of Rice Plant Leafhoppers : III. Salivary Phenolase

Effects of Nutrient Compounds on Sucking Response of the Brown Planthopper, Nilaparvata lugens (Homoptera : Delphacidae)