Author/Authors :
Arbabtafti, R. Department of Entomology - Faculty of Agriculture - Tarbiat Modares University, Tehran, iran , Y. Fathipour, R. Department of Entomology - Faculty of Agriculture - Tarbiat Modares University, Tehran, iran , Ranjbar Aghdam, H. Iranian Research Institute of Plant Protection - Agricultural Research - Education and Extension Organization (AREEO), Tehran, Iran
Abstract :
Population density and dispersion pattern of Sesamia cretica Led. was determined in
maize fields in Varamin (Ahmadabad and Khaveh) and Rey (Aminabad and Talebabad)
areas (Tehran, Iran) during two agricultural seasons, 2017 and 2018. A whole plant of
maize was selected as a sampling unit to estimate the number of S. cretica larvae. The
highest population density of S. cretica larvae per plant was recorded on the 4th and 8th
October in Aminabad, 17th and 20th September in Talebabad, 6th and 17th September in
Ahmadabad and Khaveh, in 2017 and 2018, respectively. Mean densities of the larvae per
plant were 52.62±12.53, 10.50±2.85, 17.45±3.48, 7.57±1.55 in 2017 and 12.00±5.29,
1.00±0.30, 11.05±2.36, 12.00±3.41 in 2018 in Aminabad, Talebabad, Ahmadabad, and
Khaveh, respectively. The population of captured male adults in all fields in the second
year was less than the first one. Peak numbers of male moths had a difference of 10-22
days between the two studied years. Based on the index of dispersion, the spatial
distribution of S. cretica larvae in all fields in both areas was aggregated during the two
years of study, except for Aminabad in 2018. According to Taylor’s power law, S. cretica
in Ahmadabad and Aminabad in 2017 had a random pattern, while in all fields of the
other regions it had an aggregated spatial distribution during 2017 and 2018. In Iwao's
model, the regression between the mean crowding and the density was not significant in
Aminabad and Khaveh in 2017 and Talebabad in 2018, while in the other fields indicated
the aggregated spatial distribution. The lowest estimate of the sample size was computed
by using Taylor’s power law. The results revealed that population fluctuation of S. cretica
was affected by the region, but in spatial distribution pattern, the oviposition behavior of
the pest was a much more determining factor than the region. The coefficients of the
spatial pattern can be used for improving the sampling program to calculate the
population density of S. cretica precisely.
Keywords :
Dispersal pattern , Maize , Pink stem borer , Population density
