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Invasive plants disrupt both floral and faunal communities of the invaded regions. Influence of invasive plants on ecosystem functioning and dynamics in the invaded region can be understood by taking into consideration complex interactions between native insects and non-native plants. This review attempts to synthesize available key literature on the effects of plant invasion on native insect communities and the role of native insects in control or spread of invasive plants. The toxic or attractive nature of invasive plants will have bearing on the novel associations that native insects form with the invasive plants and consequently in regulating their population. This study examines the consequences of herbivory and pollination on invasive plants upon encounters with native insects in the invaded regions and illustrates a sequence of possible changes that native insects and invasive plants interactions may bring about within a biotic community.

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This study provides the first quantitative description of vertical stratification in calling heights of ensiferan species constituting most of the dry-season nocturnal acoustic community of an evergreen forest in Kudremukh National Park in south-west India. Calling heights of an average of 26 individuals of each of the 20 ensiferan species were measured and subjected to an analysis of variance to test for differences in mean calling height between species and a cluster analysis to check for the presence of discontinuous calling height layers. There were significant differences in mean calling heights between species. Calling heights of different gryllid and tettigoniid species ranged from the ground to the canopy. More gryllid than tettigoniid species occupied the ground and herb layer. Our study revealed vertical stratification of calling heights, with discrete layers corresponding to the canopy, understorey and the ground layer. These clusters emerged from the raw data of calling heights of individuals without a priori distinction of layers. We found no significant correlation between the calling heights of species and call features, including mean dominant frequency of narrow band calls, mean syllable rate and mean duty cycle.

We evaluated trained listener-based acoustic sampling as a reliable and noninvasive method for rapid assessment of ensiferan species diversity in tropical evergreen forests. This was done by evaluating the reliability of identiWcation of species and numbers of calling individuals using psychoacoustic experiments in the laboratory and by comparing psychoacoustic sampling in the Weld with ambient noise recordings made at the same time. The reliability of correct species identiWcation by the trained listener was 100 % for 16 out of 20 species tested in the laboratory. The reliability of identifying the numbers of individuals correctly was 100% for 13 out of 20 species. The human listener performed slightly better than the instrument in detecting low frequency and broadband calls in the Weld, whereas the recorder detected high frequency calls with greater probability. To address the problem of pseudoreplication during spot sampling in the Weld, we monitored the movement of calling individuals using focal animal sampling. The average distance moved by calling individuals for 17 out of 20 species was less than 1.5 m in half an hour. We suggest that trained listener-based sampling is preferable for crickets and low frequency katydids, whereas broadband recorders are preferable for katydid species with high frequency calls for accurate estimation of ensiferan species richness and relative abundance in an area.