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Predation mediated mortality & migratory behavior of nymphs 82 Survival of nymphs 1.0 0.8 0.6 0.4 0.2 0.0 survival in exclosures survival in controls 0 2 4 6 8 10 12 14 Time passed [days] Figure 5-1: Cumulative survival of phasmid nymphs in exclosures versus controls. Survival is expressed as the probability that an individual survives past a given time (Kaplan-Meier estimate). Survival times of M. diocles nymphs differed significantly between exclosures and controls (Mantel-Cox Test; X 2 = 74.08, df = 1, P < 0.0001). Data were pooled from four experimental runs each lasting 14 days (N = 119 nymphs per treatment). Error bars show ±1 SE. Mortality of nymphs 0.6 0.5 0.4 0.3 0.2 0.1 0.0 control/night control/day exclosure/night exclosure/day 0 2 4 6 8 10 12 14 Time passed [days] Figure 5-2: Cumulative mortality (i.e., death or disappearance) of nymphs in exclosures versus controls at night and in the day. Mortality is expressed as the probability that an individual dies past a given time (Kaplan-Meier estimate). In controls, significantly more nymphs disappeared at night as compared to the daytime (Mantel-Cox Test; X 2 = 31.13, df = 1, P < 0.0001). Data were pooled from experimental runs 1, 2 and 3 (N = 89; evening checks were omitted in run 4).
Predation mediated mortality & migratory behavior of nymphs 83 Table 5-1: Disappearance or death and migratory activity of M. diocles nymphs in a field experiment with predation exclusion. Treatment No. of M. diocles nymphs Exclosure Control Chi-Square test Total 119 119 Disappeared or dead after 14 days 23 87 X 2 = 67.09, p < 0.01 Migrated 30 37 X 2 = 0.75, p = 0.39 Various invertebrate predators were recorded (Table 5-2). Spiders (2 cases) and bugs (Reduviidae) (1 case) were seen preying upon nymphs, and Ectatomma ants were repeatedly found on control plants prior to the disappearance of nymphs. The fate of any lost nymph in the control plots is either a result of 1) predation, 2) intrinsic mortality with subsequent removal by scavengers, or 3) emigration beyond the searched area. Intrinsic mortality was assumed to be the same in exclosures and controls and was therefore approximated as the proportion of nymphs having died on caged plants (19 %, i.e. 23 out of 119 nymphs; Table 5-1). This estimate proved legitimate as mortality levels in the greenhouse experiment did not differ significantly (32 %, i.e. 17 out of 53 nymphs; X 2 = 2.66, df = 1, P = 0.10). The latter correspondence also suggests that mortality levels were not considerably influenced by the exclosures. I consider disappearance due to emigration to have been negligible for two reasons. First, the search area around control plants (1 m radius) was well above the mean range nymphs moved: 47.53 cm (SD 39.13 cm, N = 29) between subsequent checks, with the 75 percent quartile lying below 72 cm. Second, overall migratory activity in controls appeared to be adequately estimated, as the proportion of moving nymphs corresponded well with exclosures (Table 5-1). This was further confirmed by the fact that the proportion of migrating nymphs in the predation-free greenhouse experiment (8 from 53 nymphs) was not different from the exclosures (30 from 119 nymphs; X 2 = 1.49, df = 1, P = 0.22). The proportion of nymphs dying on control plants due to predation was therefore estimated as follows: disappearance in controls (73%) – intrinsic mortality in exclosures (19%) – emigration from control plots (negligible) = 54%.
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ECOLOGY OF PHASMIDS (PHASMATODEA) I
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ECOLOGY OF PHASMIDS (PHASMATODEA) I
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Acknowledgements I Acknowledgements
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Table of Contents III 3 Life cycle,
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List of Figures V List of Figures F
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List of Abbreviations VII List of A
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Introduction 2 Regardless whether s
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Introduction 4 Description of phasm
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Introduction 6 Solanum and Piper (T
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Introduction 8 1.3.4 Data analysis
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Community structure & host range 10
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Page 46 and 47: Life history & potential population
Page 58 and 59: Adult female feeding preference & n
Page 92 and 93: Predation mediated mortality & migr
Page 105 and 106: Concluding remarks 91 6 Concluding
Page 107: Abstract 93 7 Abstract Herbivory is
Page 110 and 111: Literature cited 96 Basset, Y. 1997
Page 112 and 113: Literature cited 98 Brown, B. J., M
Page 114 and 115: Literature cited 100 Croat, T. B. 1
Page 116 and 117: Literature cited 102 Hagerman, A. E
Page 118 and 119: Literature cited 104 Kearsley, M. J
Page 120 and 121: Literature cited 106 McNeill, S., T
Page 122 and 123: Literature cited 108 Reich, P. B.,
Page 124 and 125: Literature cited 110 Strong, D. R.,
Page 127: Appendix 113 9 Appendix Please cont
Page 130 and 131: Appendix 1: Phasmid species previou
Page 133 and 134: Tabellarischer Lebenslauf Angaben z
Page 135: Berger J., Schaefer, M., 1997. Wild
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