İzzet Akça

Demography and Population Projection of Aphis fabae (Hemiptera: Aphididae): with Additional Comments on Life Table Research Criteria

ABSTRACT We collected developmental, survival, and reproduction data for Aphis fabae Scopoli (Hemiptera: Aphididae) reared on faba bean, Vicia faba L. ‘Sevilla’ at four constant temperatures (15, 20, 25, and 30°C), 70% relative humidity, and a photoperiod of 16:8 (L:D) h. The highest intrinsic rate of increase (r = 0.4347 d-1) and finite rate (&lgr; = 1.5445 d-1) were observed at 25°C. The population projection based on the age-stage, two-sex life table quantitatively revealed the growth potential and stage structure of the aphid. We have included the following suggestions to aid researchers in life table studies: 1) The bootstrap method should be used to estimate the variance and SEs of developmental time, survival rate, fecundity, and population parameters. 2) The required number of bootstraps is dependent on the life table data—the higher the variation among individuals, the higher the number of bootstraps should be. In most cases, we suggest that 100,000 bootstraps should be used to obtain a stable estimate of variance and SEs. 3) Computer projection based on the age-stage, two-sex life table should be used to reveal the stage structure during population growth. 4) We used a simple equation based on the total fecundity, survival rate to adult stage, and first reproductive age to detect possible errors in life table parameters. 5) To assist readers in comprehending results, life table studies should include the cohort size, preadult survival rate, number of emerged female adults, mean fecundity, survival and fecundity curves, and population parameters.

Effects of Azadirachtin on Beet Soilborne Pomovirus and Soil Biological Properties on Sugar Beet

Beet soilborne pomovirus (BSBV) is an important soilborne virus disease in growing areas of sugar beet. BSBV was transmitted by Polymyxa betae Keskin. Effects of azadirachtin on BSBV and soil biological properties were studied under a greenhouse. The presence of BSBV was tested in soil samples using bait plant test and triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELISA). The concentration of BSBV in sugar beet roots was significantly reduced by the application of azadirachtin to the soils. TAS-ELISA absorption values in 1.52, 3.04, and 7.60 ppm were lower than that 0.38 and 0.76 ppm of azadirachtin. Furthermore, in this study, it was determined the 0.38, 0.76, and 1.52 ppm doses of azadirachtin in soils had high amounts of soil biological properties (Cmic, BSR, DHA), while the 3.04 and 7.60 ppm doses had no statistical significance compared to the control treatments.

Evaluation of suppression of rhizomania disease by earthworm (Lumbricus terrestris L.) and its effects on soil microbial activity in different sugar beet cultivars

The ability of earthworm Lumbricus terrestris L. to suppress the multiplication of Beet necrotic yellow vein virus (BNYVV) transmitted by Polymyxa betae and its effects on soil microbial activity were investigated under controlled conditions. BNYVV-infested and a combination of earthworm with BNYVV-infested soil were compared to non-infested soils for their effects on plant and root weights and virus content of two different sugar beet cultivars by using partially resistant (cv. Leila) and susceptible (cv. Arosa) cultivars to the rhizomania disease. Soil testing with sugar beet baiting plants followed by enzyme-linked immunosorbent assay (ELISA) was used to diagnose virus. The results of the statistical analyses showed that total fresh plant and root weights were negatively correlated with BNYVV infection. Addition of L. terrestris significantly enhanced plant and root weights. The earthworm-added soils had higher microbial activity such as basal soil respiration and dehydrogenase activity. The presence of earthworms in the soil did not statistically suppress BNYVV infection (p < 0.05). Sugar beet production may be enhanced by using resistant cultivars with adding L. terrestris into soil where rhizomania is present.

The Estimation of Adult and Nymph Stages of Aphis fabae (Hemiptera: Aphididae) Using Artificial Neural Network

ABSTRACT In this research, the estimation of adult and nymph stages and adult of Aphis fabae was investigated using artificial neural network. Determining A. fabae nymph stages is difficult. Morphometric study of different parts of an insects body is needed to obtain an index to distinguish between different immature stages. The study was aimed to develop a model of A. fabae nymph stages and adult using length of hind tibia, antenna and body length. It was found that the constructed artificial neural network (ANN) exhibited high performance for predicting A. fabae nymph stages. Correlation was 99% and the estimation of the best ANN model was determined to be 0.016289 at epoch 18. Software computing techniques are very useful tools for precision agriculture and also determining which method gives the most accurate result.

SEX DISCRIMINATION OF ADULT CURCULIO NUCUM L. (COLEOPTERA: CURCULIONIDAE), A PEST OF HAZELNUTS IN TURKEY

The hazelnut weevil, Curculio nucum L., is the key pest of hazelnut (Corylus avellana L., Betulaceae) in many countries. Recently, increasing attention on the pest status of C. nucum in commercial orchards has accelerated the number of studies on its biology, behavior, and ecology (Ural, 1957; Tabamaishvili, 1988; Paparatti, 1990; Pucci, 1992; AliNiazee, 1997; 1998; Milenkovic and Mitrovic, 2001; Tuncer and Ecevit, 1997; Tuncer et al., 2001; Akça and Tuncer, 2005). At times, biological, behavioral, and ecological studies require researchers to determine the sex of adults without dissecting the genitalia and killing the organisms. Many earlier studies used the length of the rostrum in C. nucum as a criterion to distinguish their sex (Ural, 1957; Tabamaishvili, 1988; Sezen et al., 1999; Akça and Tuncer, 2005). In addition to this character, our previous study described several differences in average body size and elytral size between males and females in C. nucum. However, owing to large variation, sex discrimination using these characters, except rostral length, is not reliable. Rostral length is a good character to sex adult C. nucum [averaging 5.56 (4.926.65) and 3.96 (3.35-4.56) mm for female and male, respectively, differing significantly between sexes, t 0.05 (2), 49 = 30.2]; Akça and Tuncer, 2005). However, using rostral length is not convenient because it requires a device for measurement, and it appears to be affected by environmental factors. Also, the differences in rostral length can be as little as 0.5 mm, making it time-consuming and cumbersome to use, particularly for field applications (Akça and Tuncer, 2005). Duan et al. (1999) suggested the use of a suture dividing the last two abdominal tergites of males, instead of snout length, for sexing adult Anthonomus pomorum (Coleoptera: Curculionidae). Lykewise, Sappington and Spurgeon (2000) demonstrated that the tergal-notch in the eighth tergite of male Anthonomus grandis (Coleoptera: Curculionidae) is more accurate than snout characteristics for sexing the adults. This study describes a new, nondestructive character associated with abdominal tergites to discriminate male and female C. nucum adults. Volume 118, Number 1, January and February 2007 87