The orientational and feeding responses of E. devastans are determined by stimuli some of which are unspecific and others specific to the host (cotton) and nonhost (castor) plants. The green colour and humidity stimuli are unspecific and attract the leafhopper equally strongly to both the plants. Their odour is specific to each. The odour of the host (cotton) including that of its constituents camphene and α‐pinene attracts while the nonhost (castor) odour repels the leafhopper. After its arrival, unspecific mechanical contact stimuli elicit the insect's proboscis response, followed by ingestion which is determined by certain unspecific gustatory stimuli e.g., sucrose and glucose. Ingestion is further increased by the specific odour of the host (cotton) but not of the nonhost (castor) plants, resulting in a greater food‐intake from the former. Résumé ASPECTS DES RELATIONS ENTRE CERTAINS JASSIDES ET LES PLANTES. 2ÈME PARTIE—RÖLE DES STIMULI SENSORIELS DANS L'ORIENTATION ET L'ALIMENTATION Les réponses d'orientation et d'alimentation d'E. devastans sont déclenchées par des stimuli dont certains sont spécifiques et d'autres non spécifiques, soit à la plante hôte (coton) soit aux plantes non hôtes (Ricin). Ces stimuli peuvent être perçus à distance et peuvent déclencher l'orientation ou le comportement alimentaire, tandis que d'autres sont perçus par contact et ne déterminent que les seules réponses alimentaires. Parmi les stimuli perçus à distance, les stimuli‐visuels, en particulier la couleur verte et l'humidité (vapeur d'eau) ne sont pas spécifiques; tous les deux provoquent une forte attraction des Jassides. La plus grande attractivité des insectes pour le vert, de préférence à d'autres couleurs, faciliterait la rencontre avec les plantes plutôt que d'autres substrats. Les odeurs de la plante‐hôte (coton) ou de plante non hôte (ricin) sont spécifiques à chacune d'elles. L'odeur du coton comprenant celle de ses constituants camphène et α‐pinène, attire les Jassides, tandis que celles du Ricin les repousse. Cependant ces insectes sont également et fortement attirés par ces deux plantes, sans doute en raison de la faible intensité des stimuli odorants et de l'influence prépondérate de la couleur verte. Après être parvenu sur une plante ou toute autre source alimentaire des stimuli mécaniques de contact non spécifiques provoquent l'extension du rostre quelle que soit la nature chimique du substrat. La réponse du rostre est suivie par l'ingestion de nourriture et d'eau. Certains stimuli gustatifs de l'aliment ingéré par exemple des sucres, conditionnent la quantité absorbée: l sucrose à 0,01 M est le plus stimulant, le glucose l'est moins et le fructose demeure sans action. La quantité de nourriture ingérée est par ailleurs accrue par stimuli de l'odeur spécifique de l'hôte (coton), mais non par celle des plantes non hôtes (Ricin). En conséquence les Jassides prélèvent plus de nourriture aux dépens du coton qu'aux dépens des plantes non hötes.

Differences in the establishment of the leafhoppers Empoasca devastans and E. kerri motti on different plants are determined by an interaction of the following chief types of their responses in six main stages: (1) Orientation, (2) Feeding, (3) Metabolic utilization of the ingested food determining its nutritive value, (4) Growth, (5) Survival and egg‐production, (6) Oviposition. Both the leafhoppers showed equally high attraction and proboscis response to all the six test plants, namely, Gossypium hirsutum, G. herbaceum, G. arboreum, Solanum melongena, S. tuberosum, and Ricinus communis. The quantity and nutritive value of the food ingested by E. devastans decreased in the order: G. hirsutum, S. melongena, S. tuberosum, G. herbaceum, G. arboreum, and R. communis. The growth, particularly in respect of moulting/metamorphosis to adult, also decreased in the same order except that S. melongena was superior to G. hirsutum. But, the suitability of the plants for adult survival decreased in the order: S. tuberosum, S. melongena, G. hirsutum, G. herbaceum, G. arboreum, R. communis. The egg‐production and ovipositional response decreased in the order: S. melongena, G. hirsutum, S. tuberosum, G. herbaceum, G. arboreum, R. communis. The interaction of the above responses would render S. melongena most suitable for the establishment of E. devastans and the suitability of the remaining plants would decrease in the order: G. hirsutum, S. tuberosum, G. herbaceum, and G. arboreum, while R. communis would be completely unsuitable. The quantity and nutritive value of the food ingested by E. kerri motti from R. communis as well as its growth, survival, egg‐production and oviposition on this plant were the highest. Therefore, this plant would be most suitable for the insect's establishment. S. tuberosum and G. hirsutum were next to R. communis in respect of the quantity and nutritive value of the food ingested, growth and adult survival, but there was no egg‐production nor oviposition. Therefore, these two plants would support the growth of the larvae and survival of the adults, if present, but not reproduction. The remaining plants were completely unsuitable for both egg‐production and oviposition, and therefore would not support the insect's establishment. Résumé MODES DE RELATIONS ENTRE CERT AINES ESPÈCES D'EMPOASCA ET LEURS PLANTES‐HÔTES. ***IÈRE PARTIE — RÉPONSES AUX ESPÈCES DE PLANTES Les différences observees dans les conditions d'installation des Jassides Empoasca devastans et E. kerri motti sur différentes espèces de plantes sont déterminées par la résultante des réponses aux six principales phases des rapports de l'insecte avec la plante: (1) orientation, (2) alimentation, (3) utilisation métabolique de la nourriture absorbée, ce qui conditionne sa valeur nutritive, (4) croissance, (5) survie et fécondiTÉ, (6) conditions de ponte. Les deux espèces d'Empoasca montrent une même grande attraction et une réponse positive de la posture du proboscis, à chacune des six espèces de plantes tesTÉes, c'est‐à‐dire Gossypium hirsutum...

Informationon the range and interaction of certain sensory stimuli determining the orientational responses of Empoasca devastans to the host (cotton) and nonhost (castor) plants is given. These responses of the leafhoppers, resulting in their arrival on various plants during host selection, are determined by the sensory stimuli from both the plants and from their background. The responses differ qualitatively and quantitatively according to the combination patterns of the different sensory stimuli perceived. The humidity (water vapour) and odour stimuli from the plants attract the insects up to only 1 cm. The humidity from the background of the plants in an irrigated bed attracts the insects from a longer distance (180 cm). The visual stimuli from the plants, particularly colour, attract the insects from the maximum distance (360 cm). When presented the same stimuli, e.g., cotton plants, in two different directions at different distances, the insects show a greater attraction to the nearer plants. The background stimuli which influence the insects' orientational responses to the plants include light and humidity. The insects show a greater attraction to a plant in a higher intensity of light or humidity than to the plant in a lower intensity of light or humidity. Even the nonhost (castor) plant, under high intensity conditions, attracts the insects more than the host (cotton) plant under low intensity conditions. The possibility of manoeuvring the orientational behaviour of the leafhoppers for their control is considered.The role of orientational and feeding responses of the leafhopper Empousca devmtans Dist. in determining its establishment on different plants has been considered in Part I and the nature of stimuli determining the above responses in Part II of the present series of papers. The orientational responses of the leafhopper are determined by three distancestimuli of the plants, i.e., visual (green colour), humidity (water vapour) and odour. The colour and humidity of the host (cotton) and nonhost (castor) plants are unspecific, being almost identical, and attract the leafhopper equally strongly. The odour of the two plants is specific to each, that of the host (cotton) attracting whiIe the nonhost (castor) odour repelling the insect. After its arrival on a plant, the leafhopper's feeding response and ingestion of food are determined by certain gustatory stimuli which may be unspecific and, also, by the specific odour of the host (cotton) plant. Further information on the role of the distance-stimuli, particularly their range and interaction, in determining the orientation of the leafhopper to the host (cotton) and nonhost (castor) plants is given here. RELATIONSHIPS BETWEEN LEAFHOPPERS AND PLANTS, 111* In Fig. 1, the width and height of the chamber are shown as 30 cm instead of 60 cm which is the actual dimension (Footnote added in proof).

Various dyes present in water have adverse effect on human life, plants and on animals. There are various technologies used to effectively remove these dyes from effluent water.The methodology, advantages and disadvantages of various technologies are discussed in detail. Special emphasis is made on removal of azo dyes using biosorption method. Kinetic procedure of biosorption is also discussed in detail.

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