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1. Dispersal and host detection are behaviours promoting the spread of invading populations in a landscape matrix. In fragmented landscapes, the spatial arrangement of habitat structure affects the dispersal success of organisms. 2. The aim of the present study was to determine the long distance dispersal capabilities of two non‐native pine bark beetles (Hylurgus ligniperda and Hylastes ater) in a modified and fragmented landscape with non‐native pine trees. The role of pine density in relation to the abundance of dispersing beetles was also investigated. 3. This study took place in the Southern Alps, New Zealand. A network of insect panel traps was installed in remote valleys at known distances from pine resources (plantations or windbreaks). Beetle abundance was compared with spatially weighted estimates of nearby pine plantations and pine windbreaks. 4. Both beetles were found ≥25 km from the nearest host patch, indicating strong dispersal and host detection capabilities. Small pine patches appear to serve as stepping stones, promoting spread through the landscape. Hylurgus ligniperda (F.) abundance had a strong inverse association with pine plantations and windbreaks, whereas H. ater abundance was not correlated with distance to pine plantations but positively correlated with distance to pine windbreaks, probably reflecting differences in biology and niche preferences. Host availability and dispersed beetle abundance are the proposed limiting factors impeding the spread of these beetles. 5. These mechanistic insights into the spread and persistence of H. ater and H. ligniperda in a fragmented landscape provide ecologists and land managers with a better understanding of factors leading to successful invasion events, particularly in relation to the importance of long‐distance dispersal ability and the distribution and size of host patches.  相似文献   
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ABSTRACT. Horizontal head movements of the praying mantis, Sphodromantis lineola Burm., were recorded continuously. They responded to the presence of a live blowfly prey in the antero-lateral visual field with a rapid saccadic head movement. The angular movement of a fixation saccade was correlated positively to the displacement of the prey from the prothoracic midline. Saccade magnitude and velocity are related. After the stimulus moved out of the visual field, the mantis made a second saccadic head movement, a return saccade towards the body midline. We observed return saccades in which the head overshot or undershot the body midline, as well as saccades which returned the head exactly to its initial position. In 92% of trials with intact mantids, the return movement succeeded eventually in rotating the head back to its initial position, whereas after removal of the neck hair plates this occurred in only 47% of trials. There is a consistent relation between saccade extent and velocity. Velocities of return saccades were slower than those of fixation saccades. It is suggested that sensory inputs from the neck hair plate proprioceptors modify both the magnitude and the angular velocity of fixation and return saccadic head movements.  相似文献   
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