Patterns of Relationships Between Certain Leafhoppers and Plants, Part Iii. Range and Interaction of Sensory Stimuli

Abstract

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).

Cropping Systems, Insect Movement, and the Spread of Insect-Transmitted Diseases in Crops

“…Chemical confusion is unlikely to be applicable to most homopteran insects, however, because aphids and leafhoppers are known to be largely unaffected by olfactory stimuli (Kennedy et aI., 1959a, b;Saxena and Saxena, 1975).…”

Visual Detection of Plants by Herbivorous Insects

“…Rather, relative values, measured in animal body lengths, may be a better descriptor of the perception distance of insects (8 1, 91). For example, the relative distance over which certain leathoppers are visually attracted to a plant patch (surface = ca 900 cm2) is equal to ca 600 leafuopper body lengths (1 length = ca 6 mm, distance of plant perception = ca 3.6 m) (139). A parallel situation for a human (height = 1.8 m) would be attraction to a plant equivalent in height to the Statue of Liberty in New York (height = 90 m) fr om a distance of ca 1.1 km.…”

Random Search by Herbivorous Insects: A Simulation Model

“…My approach has been to quantify the success of insects at finding host plants as a function of biologically meaningful model parameters: plant dispersion, plant density, stand size, average move length, "radius of detection" (the distance within which an insect can detect host plants), turning angle concentration, and probability of death (both while moving and resting). However, since plant diversity may interfere with an insect's ability to detect host plants (Saxena and Saxena 1975, Smith 1976, Rausher 1981, Andow 1985, for some species of insects the effects of plant diversity may be implicitly examined by varying the radius of detection. Plant diversity is the one commonly cited (e.g., Stanton 1983) feature of vegetation texture that my model does not directly address.…”