RESUMEN

The citrus red mite, Panonychus citri McGregor, is a key pest of different citrus species in various parts of the world. Considering the key role of resistant host plants in integrated pest management strategies, we evaluated the effects of five citrus species including grapefruit (Citrus paradisi), lime (Citrus aurantifolia), tangerine (Citrus reticulata), orange (Citrus sinensis), and sour orange (Citrus aurantium) on life table parameters of P. citri under laboratory conditions (25 ± 1°C, 65 ± 5% RH, 16:8 L:D). In addition, biochemical traits of the citrus plant species were evaluated in order to understand any possible relationship between important life history parameters with biochemical metabolites of citrus plant leaves. Phytochemicals were determined in leaf extract of citrus plant species. Various citrus species had significant effects on life history and demographical parameters of P. citri. The longest pre-adult time was observed on grapefruit (16.52 ± 0.43 days). Higher fecundity rate was on orange (15.05 ± 2.41 eggs) and tangerine (14.60 ± 3.07 eggs) and the lowest was on grapefruit (7.21 ± 2.00 eggs). The highest intrinsic rate of increase (r) was recorded as 0.071 (day-1) on tangerine, and the lowest value of this parameter was obtained on grapefruit (0.016 day-1). Significant correlations were observed between life history parameters with biochemical metabolites (carbohydrate, phenolic compounds, anthocyanin, and flavonoid). The results revealed that grapefruit was a relatively resistant host plant and tangerine was the most suitable host plant for feeding of P. citri. Our findings could be helpful for sustainable management of P. citri in citrus orchards.

Asunto(s)

RESUMEN

Plant-herbivore interactions can be influenced by plant developmental stages. Effects of four different developmental stages of pomegranate fruit (Hazelnut size, Walnut size, Juicy, and Ripe) were investigated on life table parameters, nutritional yield, and energy contents (protein, glycogen, and lipid) of Ectomyelois ceratoniae (Zeller) under controlled conditions in two pomegranate cultivars, namely Shahvare-Danesefid and Esfahani-Daneghermez as susceptible and resistant cultivars, respectively. Biochemical characteristics of the four developmental stages were determined, and a correlation was made with life-history and nutritional responses of E. ceratoniae. Significant differences were observed in developmental time and adult fecundity of E. ceratoniae across various tested stages in both pomegranate cultivars. The highest value of intrinsic rate of increase (rm) was found in Juicy and lowest in Hazelnut-size stage of Shahvare-Danesefid. The highest rm value was on Walnut-size and Juicy stages, and the lower rate was obtained from the feeding of E. ceratoniae on Ripe and Hazelnut-size stages in Esfahani-Daneghermez. A higher relative growth rate (RGR) was observed in Juicy (in Shahvare-Danesefid) and Walnut-size stages (in Esfahani-Daneghermez) when compared with other developmental stages tested. Life-history parameters of E. ceratoniae were correlated with biochemical qualities of pomegranate stages. Results indicated Juicy (Shahvare-Danesefid) and Walnut-size stages (Esfahani-Daneghermez) were relatively susceptible pomegranate stages, and Hazelnut-size and Ripe stages were unsuitable for feeding of E. ceratoniae in Shahvare-Danesefid and Esfahani-Daneghermez, respectively. Findings of this research could aid in the development of integrated management programs of E. ceratoniae in pomegranate orchards.

Asunto(s)

RESUMEN

The carob moth, Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), is the main pest of pomegranate, Punica granatum L., in Iran and many parts of the world. In this study, the effects of 11 commercial cultivars of pomegranate (Aban-Mahi, Esfahani-Daneghermez, Gabri, Gorche-Tafti, Malase-Danesyah, Malase-Yazdi, Shahvare-Daneghermez, Shahvare-Danesefid, Tabolarze-Mehrmahi, Tafti, and Toghe-Gardan) were evaluated on life history variables, nutritional performance, and energy reserves of E. ceratoniae under the following laboratory conditions: 30 ± 1°C, 60 ± 5% RH, and a photoperiod of 14:10 (L:D) hours. In addition, biochemical characteristics of the tested cultivars were assessed in order to understand any possible correlation between important demographic parameters and nutritional properties with biochemical features of pomegranate juice. Our research showed that various pomegranate cultivars have significant effects on life history, demographical parameters, nutritional indices, and energy reserves of E. ceratoniae. The shortest development time was observed on Shahvare-Danesefid cultivar and the longest was on Esfahani-Daneghermez and Malase-Danesyah cultivars. The highest intrinsic rate of increase (r m ) was observed on Shahvare-Danesefid and the lowest was on Esfahani-Daneghermez. Six major anthocyanin compounds were detected in juice of various pomegranate cultivars. Significant positive or negative correlations were observed between life history variables and nutritional characteristics with biochemical traits of pomegranate cultivars. The results indicated that Shahvare-Danesefid was a relatively susceptible pomegranate cultivar and Esfahani-Daneghermez was the least appropriate (most resistant) cultivar for feeding of E. ceratoniae, which could be useful in the development of integrated pest management strategies for this pest.

RESUMEN

The melon aphid, Aphis gossypii Glover, is a cosmopolitan pest that infests and damages a wide range of crop plants, especially cucurbits. It is a host of the coccinellid predator, Hippodamia variegata (Goeze), that has the potential to suppress the pest on leaves of cucumber plants grown in greenhouses. Melon aphids were reared on either Storm or Khasib cucumber cultivars to determine whether there would be a difference in their development and reproduction. The aphids from each cultivar were fed to H. variegata adults to assess their effects on the life history of the predator. The aphid population reared on Khasib leaves increased faster than the population on Storm leaves; however, the predators fed aphids from Storm leaves had a higher rate of population growth. Thus, the intrinsic rate of increase and net reproductive rate were greater for aphids reared on Khasib leaves but lower for H. variegata fed those aphids compared with aphids reared on the Storm cultivar. Additionally, clean and aphid-infested leaves from both cultivars were analyzed for total flavonoids, phenol, and chlorophyll, and the density of leaf trichomes was measured. The Storm leaves contained higher amounts of flavonoids and phenol, less chlorophyll, and a greater density of trichomes. Regardless of cucurbit cultivar, aphid feeding increased the flavonoids and phenol content and decreased the amount of chlorophyll.

Asunto(s)

RESUMEN

The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is a serious pest of the potato, Solanum tuberosum L. (Solanales: Solanaceae), in both fields and stores in tropical and subtropical regions. In the present study, the susceptibility of different potato cultivars to P. operculella was evaluated by measuring life table parameters. Tests were undertaken with leaves and tubers of 10 potato cultivars in the laboratory: Agria, Agata, Almera, Arinda, Baneba, Fiana, Marfona, Ramus, Satina, and Volvox. All parameters showed significant differences among tested cultivars. The longest mean generation times were observed on Marfona and Satina cultivars in the experiments on potato leaves and tubers, respectively. The lowest reproductive rate was observed on leaves and tubers of Marfona cultivar. Correspondingly, the lowest values of intrinsic rate of increase and the lowest finite rate of increase were also obtained on Marfona cultivar in tests on potato leaves and tubers. The highest intrinsic rate of incrase values were observed on Arinda and Baneba in the tests on leaves and tubers, respectively. The intrinsic rates of increase were significantly higher on potato leaves than on potato tubers. The lower performance of P. operculella on Marfona cultivar indicated that this cultivar is relatively less susceptible this pest and could be used in integrated pest management programs of P. operculella.

Asunto(s)

RESUMEN

The development and cultivation of tomato cultivars that are resistant to the tomato fruit borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), are very limited in Iran and other parts of the world because of the lack of information about resistant tomato cultivars to minimize the use of insecticides. Therefore, the present study was carried out to identify alternative methods to chemical control. Nutritional performance of the larval stages (fourth, fifth, and sixth instars) of H. armigera on fruit of eight tomato cultivars, including SUN 6108 f1, Rio grande UG, Korral, Super strain B, CH falat, Hed rio grande, Cal.JN3, and Super crystal, was studied under laboratory conditions. Fourth instars reared on CH falat and SUN 6108 f1 respectively showed the highest and lowest values of approximate digestibility. The highest values of efficiency of conversion of ingested food and efficiency of conversion of digested food of fifth instars were on Super strain B. The relative consumption rate and relative growth rate values of the sixth instars were the highest on Korral. The highest and lowest values of consumption index of sixth instars were on Super strain B and Hed rio grande, respectively. The efficiency of conversion of ingested food and efficiency of conversion of digested food values of whole larval instars were the highest on Hed rio grande and lowest on Rio grande UG. The results of nutritional indices indicated that Rio grande UG is an unsuitable host for H. armigera.

Asunto(s)