International Journal of Entomology and Nematology Research (IJENR)

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Population Dynamics of African Palm Weevil (Rhynchophorus phoenicis F.) on Breeding Sites of Oil Palm (Elaeis guineensis Jacq.) in Niger Delta, Nigeria. (Published)

Population dynamics of African palm weevil (APW) (Rhynchophorus phoenicis F.) was studied. Four oil palms were randomly selected and sizeable wounds were created, using an axe and cutlass and monitored for arrival of APWs for 21 days. Total number of one hundred and fourty-eighty (n=148) weevils were counted at the breeding sites. The total number of males was 52(35.13%), while the total number of females was 96(64.87%) which corresponds to sex-ratio of 1:1.9. Colonization of the breeding sites commenced with the arrival of few females in the morning (7-9am) followed by the males at noon (1-2pm) and significantly increased in population to peak by 1-3pm till evening and steadily declined at dusk. The population of APWs was significantly higher (P<0.05) in younger oil palms than older palms: Youngest Palm (P1) had 62, Younger Palm (P2) had 66 and Older Palm (P3) had only 20, while the Oldest matured Palm (P4) had no weevil because the tissues did not decompose. Optimum temperature and relative humidity which favoured the aggregation of R. phoenicis at the breeding site was 300C – 310C and 75-82% respectively. Also, the population of R. phoenicis at the breeding sites was highly positively and negatively correlated with the temperature (r=0.96) and relative humidity (r=-0.98) respectively.  The APWs were sluggish in the morning but became active in feeding, courtship, mating and oviposition of eggs at noon when the temperature of the day become hotter and declined at dusk.

Citation: Thomas N. Commander and Dimkpa O.N. Stanley (2022) Population Dynamics of African Palm Weevil (Rhynchophorus  phoenicis  F.) on Breeding Sites of Oil Palm (Elaeis guineensis Jacq.) in Niger Delta, Nigeria, International Journal of Entomology and Nematology Research, Vol.6, No.1, pp.1-10

Keywords: Population, Rhynchophorus phoenicis, breeding site, oil palm Elaeis guineensis., sex-ratio

Effect of Different Temperatures on Some Biological Parameters of Anisopteromalus Calandrae, (Howard) (Hymenoptera: Pteromalidae) and Population Fluctuation of the Parasitoid and their Insect Hosts of the Genus Sitophilus (Coleoptera: Curculionidae) (Published)

Population fluctuation of some different insect species of the genus Sitophilus (Coleoptera: Curculionidae) and their parasitoid, Anisopteromalus calandrae, (Howard) (Hymenoptera: Pteromalidae) were studied at El-Beheira Governorate (Egypt). The present results show that during the first year 2013 S. oryzae reached its peak in August where the average number was 510 adult per kilogram wheat. While S. granarius and S. zeamais reached its peak at December and September achieved 401 and 300 adults per kilogram grain, respectively. The parasitoid A. calandrae was active from March to November and reached its peak in August achieved 112 parasitoid per kilogram. The parasitoid sex ratios of A. calandrae increased gradually with increasing temperature and reached its peak in August of the year 2013 recorded 2.3 female to 1male. The duration of immature stages of the parasitoid A. calandrae decreased with increasing temperature where it was extended from 26.89 day at 20°C to 11.55 day at 35°C. The parasitoid total numbers also increased gradually with increasing temperature from 20°C to 30 °C, recorded 67.67 at 30 °C. Then, the numbers decreased also at 35 °C recorded 62.67. The results illustrated also that there were significant difference in sex ratio between the temperature of 20 °C and 35 °C. Where, at 20°C the sex ratio was 2 females:1male. Whilst, at 35 °C the sex ratio was 2.3 females:1male. No significant differences in the sex ratio were observed between the temperature of 20, 25 °C and 30 °C. From the previous results the temperature of 30 °C was the most desirable temperature for the activity of the parasitoid.

Keywords: Anisopteromalus Calandrae, Biological Parameter, Insect Hosts, Parasitoid, Population, Temperature

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