Search

Helicoverpa armigera (Hübner) is one of the invasive pests of crops worldwide, and several studies have focused to compare the growth, consumption, and digestion of H. armigera larvae on different plants. However, studies evaluating the insect’s food consumption and digestive physiological response using biochemical profile of sunflower cultivars are scarce. In this research, the impacts of various sunflower cultivars (Golsa, Ghasem, Shams, and Zarrin) based on artificial diet were evaluated on enzymes activity and nutritional responses of H. armigera. Among the different sunflower cultivars, the relative growth rate (RGR), efficiency of conversion of ingested food (ECI), and efficiency of conversion of digested food (ECD) were highest on Ghasem. Likewise, the heaviest weight of larvae and pupae was obtained on Ghasem, while the lightest was found on Zarrin. The highest proteolytic activity was detected on Zarrin, whereas the highest amylolytic activities were found on Ghasem and Shams. In addition, ECD and RGR values of H. armigera larvae were negatively correlated with secondary metabolites content (phenol). The cluster analysis revealed that Ghasem was a nutritionally appropriate cultivar for H. armigera, while Zarrin illustrated the greatest level of tolerance against this polyphagous pest. These results could be useful in selection of sunflower cultivars for cultivation and breeding programs that entail H. armigera control.

Sixteen date palm cultivars were studied for their susceptibility to the date palm dust mite, Oligonychus afrasiaticus, at the Date Palm and Tropical Fruit Research Institute of Bushehr, Iran. Three date palms naturally infested by O. afrasiaticus were randomly selected per cultivar. Four fruit strands per bunch of each sampling tree were randomly collected, and the number of healthy and infested fruits was counted. Fruit physicochemical attributes of these cultivars were also recorded at the Kimri stage using standard procedures. The analysis was carried out according to a completely randomized design. The results revealed significant differences among cultivars regarding susceptibility to O. afrasiaticus. The cultivars Barahi, Maktoub, Haleli, and Deglet Noor, were more resistant to the date palm dust mite than the other cultivars. Significant differences among cultivars were also observed in all tested physicochemical characteristics. The percentage of infestation had a significant positive correlation with the Kernel weight, fruit length, and the number of strands. Tannin content ranged from 0.97 to 8.13%, total soluble solids (TSS) from 10.00 to 70.00% Brix, and titratable acidity from 0.70 to 1.50%. No significant correlation was observed between the chemical characteristics of date fruits and infestation to the mite. Such information can be used to screen date palm cultivars for date fruit processing industries and breeding programs.

Tomato leafminer, Tuta absoluta has invaded Iran in recent years and rapidly turned into an important pest of tomato crops in open fields and greenhouses. Tomato is the preferred host of the pest. However, preliminary observations have shown that it can feed and reproduce on the other Solanaceous crops like eggplant and potato. In his study, the fitness of tomato leafminer has been investigated on fifteen commonly cultivated eggplant genotypes including Ghasri Dezful, Paboland Yazd, Mahali Jahrom, Shendabad, Dastgerd Esfahan, Sarkhoun Bandarabas, Chahboland Neishabur, Ghalami Varamin, Black Beauty, Blacky, Yalda, Lady, Linda, Lima and Kime in a greenhouse with the mean daily temperature of 25 ± 2°C, 60 ± 5% Relative Humidity and a natural photoperiod during the May and June. The ovipositional preference of females and some biological parameters like development times and survival rates of egg, larva and pupa, pupal weight and sex ratio have been evaluated on the plant genotypes using free-choice and no-choice tests. Significant differences have been revealed in the number of daily oviposited eggs on both potted plants and excised leaves and in all biological parameters except pupal weight and sex ratio among the eggplant genotypes throughout the experiments. The ovipositional preference of the females was significantly correlated and negatively correlated respectively with chlorophyll content of the leaves of eggplant genotypes (P < 0.01) and with trichome density on the underside of the entire leaf surface (P < 0.05). The eggplant genotypes were clustered into three main categories of resistant (Kime), semi-resistant (Black Beauty and Blacky) and semi-susceptible (other genotypes) using Ward-1963 hierarchical clustering method. The observed differences among the examined genotypes can be used in cropping systems for designing of eggplant breeding and tomato leafminer management programs.