Life table parameters and development of Aphis nerri (Hem.: Aphididae) at five different temperatures under laboratory conditions

An investigation was carried out to study the life history of Aphis nerri Boyer de Fonscolombe on oleander, Nerium oleander L., under laboratory conditions (RH of 70 ± 5% and a 16: 8 (L: D) h photoperiod) based on the age-stage, two-sex life table at 10, 15, 20, 25 and 30 ºC. Duration of total pre-adult stages was 35.61 ± 0.833, 19.6 ± 0.343, 12.02 ± 0.243, 9.12 ± 0.182 and 7.42 ± 0.115 days at 10, 15, 20, 25 and 30 ºC, respectively. As temperature increased, the developmental time and longevity of the A. nerri shortened. The shortest developmental time (17.72 ± 0.244 days) and longevity (10.3 ± 0.234 days) were obtained at 30 ºC. With decreasing temperature, age-stage survivorship (lx) extended. Maximum fecundity of females was observed at 25 ºC with 25.54 ± 0.76 nymphs per female. The intrinsic rates of increase (r) at these temperatures were 0.012 ± 0.0014, 0.075 ± 0.0016, 0.13 ± 0.001, 0.23 ± 0.003 and 0.24 ± 0.003 d-1, respectively. The highest net reproductive rate (R0) was at 25 ºC (25.56 ± 0.73) and the lowest value was at 10 ºC (2.58 ± 0.28). According to our results, 25-30 ºC were the optimum temperature range for A. nerri population growth

Sequential sampling of Rhopalosiphum maidis and Schizaphis graminum (Hem.: Aphididae) in wheat fields of Badjgah, Fars province, Iran

Between 2010 and 2011, spatial distribution and fixed precision sequential sampling plans were determined for two aphids, Rhopalosiphum maidis F. and Schizaphis graminum R., in wheat fields in Badjgah countryside of Iranian Fars province. For this purpose, two fields of two hectares each were selected and sampled on weekly basis. Each sample consisted of 200 randomly selected wheat plants along with the total number of counted aphids. Based on RV, the best sample unit was four stems. This data was used to describe spatial distribution pattern of R. maidis and S. graminum by Taylor’s power law (TPL) and Iwao’s patchiness regression methods. The results indicated aggregated spatial distribution of aphids' populations in wheat fields, based on the mentioned methods. The TPL provided a better description of the aphids' spatial distribution. Since regression line slopes were not significantly different for S. graminum and R. maidis, the same Green model was proposed for both species. In this model, minimum numbers of samples were 20, 12 and 9 for precision levels of 0.15, 0.25 and 0.3, respectively. Comparing Green and conventional methods in 0.15, 0.25 and 0.3 precision levels showed that the number of required samples were reduced 77.8 ± 1.05, 78.3 ± 0.91 and 81.4 ± 0.81 percent, respectively. Based on Wilson and Room's model, when the mean populations of aphids were 1.6, 3.86 and 5.62, the proportion of infestation in the field were 0.5, 0.75 and 0.85, respectively. Therefore, by increasing the infestation percentage of the samples, the number of required samples will be reduced

First record of Goniozus legneri (Hym.: Bethylidae), the larval ectoparasitoid of carob moth, in Iran

A larval parasitoid of carob moth, Ectomyelois ceratoniae (Zeller), was collected in pomegranate orchards in Fars province, Iran, during 2009-2010. This parasitoid, which is newly recorded from Iran, was identified as Goniozus legneri Gordh (Hym.: Bethylidae) by J. de Rond (Lelystad, The Netherlands)

Dispersion pattern and fixed precision sequential sampling of Sitobion avenae (Fabricus) (Hemiptera: Aphididae) in wheat fields of Badjgah (Fars province) in Iran

Understanding the dispersion pattern of a species is an important pre-requisite for developing an effective pest management program. In this study, four hundred wheat plants were surveyed for <em>Sitobion avenae</em> twice a week during 2010 and 2011 growing seasons in two fields of Badjgah (Fars province) in Iran. In each field only one of the two cultivers of Bahar or Shiraz was planted. Analysis of spatial distribution pattern using Taylor’s power law and Iwao’s regression model showed that <em>S. avenae</em> exhibited an aggregated distribution on wheat. Taylor’s power law was estimated from 84 data sets and fitted the data better than Iwao’s regression model. The optimal sample sizes needed for fixed precision levels of 0.25 and 0.30 were estimated using Taylor’s regression coefficients, and the required sample sizes increased dramatically with increased levels of precision. Therefore, the samplingplan we presented here should be used as a tool for an efficient estimation of <em>S. avenae</em> population density in wheat fields for pest management decision

A six-arm olfactometer for analysing olfactory responses of Goniozus legneri Gordh (Hymenoptera: Bethylidae), the larval ectoparasitoid of carob moth

The behavioural responses of <em>Goniozus</em> <em>legneri</em> were investigated in a six-arm olfactometer. Among the different odours examined, carob moth (<em>Ectomyelois</em> <em>ceratoniae</em> Zeller) frass elicited the highest olfactory responses, while <em>Ephestisa</em> larvae, which were less suitable hosts, elicited the lowest response. The different preferences to various odours suggest that <em>Goniozus</em> <em>legneri</em> can discriminate among suitable and less suitable insect hosts