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A population study of the coconut pest Segestidea uniformis (Willemse) (Orthoptera: Tettigoniidae) on an equatorial island

Published online by Cambridge University Press:  10 July 2009

P. M. Room ,
C. H. Perry  and
P. T. Bailey
P. M. Room
Affiliation:
Department of Primary Industry, Box 2417, Konedobu, Papua New Guinea
C. H. Perry
Affiliation:
Department of Primary Industry, Box 2417, Konedobu, Papua New Guinea
P. T. Bailey
Affiliation:
Department of Primary Industry, Box 2417, Konedobu, Papua New Guinea
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Abstract

A population of the coconut pest Segestidea uniformis (Willemse) was monitored on a small island 2° from the equator in Papua New Guinea between 1973 and 1978. Totals of 54 000 first-instar nymphs were caught on sticky traps on palm trunks and 8750 other nymphs and adults were recovered from the crowns of palms. Generations were completely overlapping, and there was no evidence of seasonality in population fluctuations. The sex ratio was 50:50 in the first six instars, but 90% of seventh instars and 30% of adults were female. Explanations for these variations are given. The population declined from an annual mean of 24 individuals of all ages per palm crown in 1973 to 9 in 1976 and increased again to 29 in 1978. Most post-hatching mortality occurred as first instars climbed from the ground to the crown of palms, probably due to the lizard Gehyra oceanica and rainfall. The number of adults was more sensitive to mortality occurring after the first instars had arrived in the crowns. This mortality appeared to be related to the duration of periods without rainfall, supporting earlier observations that damaging outbreaks of S. uniformis populations do not occur in places which experience a regular dry season. Production of coconuts appeared to be inversely related to the population density of S. uniformis, which did not rise above a level estimated to cause 20% defoliation of the palms during the study. Nut production also seemed to be related to the number of hours of sunshine received in the preceding 12 months. Biological control aimed at nymphs and adults in palm crowns is suggested as an option for controlling S. uniformis which deserves investigation.

Type
Original Articles
Information
Bulletin of Entomological Research , Volume 74 , Issue 3 , September 1984 , pp. 439 - 451
Copyright
Copyright © Cambridge University Press 1984

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