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The population of spider feeding on insect pests of cotton was observed throughout the growth period of the crop, being maximum in the month of July. Chrysoperla was observed from second fortnight of June to harvesting of the crop being maximum in November. The incidence of coccinellids was recorded from the middle of August to middle of September and remained till harvesting of the crop being maximum in the first fortnight of November. A positive significant effect of maximum and minimum temperature on spider and negative significant effect on population of chrysoperla and coccinellids was recorded. Evening RH exerted positive significant effect on spider and negative significant effect on coccinellids.
Two important lady beetle species commonly found in alfalfa fields in Iran are the variegated lady beetle Hippodamia variegata Goeze and the seven spotted lady beetle Coccinella septempunctata (Linnaeus, 1758) (Coleoptera: Coccinellidae). These two species attack many aphid species including the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). In this study, the seasonal population changes of A. pisum, H. variegata, C. septempunctata and the parasitoid, Dinocampus coccinellae (Schrank) (Hymenoptera: Braconidae) were studied in alfalfa fields in the 2012 and 2013 seasonal periods. The highest ladybird densities were noted on July 5, 2012 and on September 6, 2013 (17.2±2.8 and 13.4±1.6) individuals per 20 sweeps, respectively. Parasitism rates by D. coccinellae ranged from approximately 3 to 6% in two subsequent years, respectively. Parasitism was higher early in the growing season. Most parasitised ladybirds were females. There was no significant relationship between the temperature and relative humidity with pea aphid populations, although the aphid populations declined during the hot summer period. In contrast, the relationship between temperature and the H. variegata population was significant and positive in both years of the study. It has been shown that these lady beetle species have a major role in reducing the pea aphid populations in alfalfa fields. Due to the relatively low percentage of field parasitism by D. coccinellae, this parasite might not reduce the biocontrol efficiency of lady beetle species.
The idea of biological control is based on a pest management with deliberate using of antagonistic organisms. Inundative biological control has already successed and become an essential element of integrated pest management programmes. Some literature reports, as well as growers’ experience reveal that effective biological control methods of numerous pest species are available, and they can be easily used in practice, especially in greenhouses crops. According to the new Polish Plant Protection Act, biological methods should be used prior to any application of chemical products. Thus, biological control is now a priority in plant protection. Currently, the following biocontrol agents are recommended: three species of entomopathogenic nematodes (Steinernema feltiae, Heterorhabditis megidis, Phasmophrabditis hermaphrodita), only one biopesticides Preferal (Isaria fumosorosea), 33 species of beneficial organisms against pests and two biopesticides: Contans (Coniothyrium minitans), Polyversum (Pytium oligandrum) against diseases in greenhouses crops in Poland.
The difference between biotic potential of a species and its actual abundance defines the environmental resistance or the effect of all factors that limit the biotic potential. The paper reviews practical exploration of major limitation factors in suppression of the exponential growth of a pest population under „unlimited” carrying capacity (food availability) of cultivated crop in agrocenosis. The following methods are presented: (a) using detrimental alternated food quality of resistant crop cultivars affecting pest population growth and the value of moderate level of resistance in the integrated pest management (IPM); (b) saving natural enemies by using selectively insecticides to upgrade the conservation biological control agents and (c) biodiversity and habitat management to provide suitable environment for natural enemies. The existing gaps in the scientist’s collected experimental data and knowledge and farmer’s practices on the pesticide selectivity for natural enemies still lead to some pest outbreaks in Poland. The evolution in research priorities and recommendations on the role of natural enemies in various agrocenoses by the IOBC working group on “Landscape management for functional biodiversity” indicated the shift from an individual field scale to the landscape scale and the needs for multidiscipline approach.
This paper presents the ultrastructure and characteristic features of Nosema leptinotarsae infecting L. decemlineata collected in Trabzon (Turkey). Fresh spores are oval, 4.69 ± 0.19 μm in length and 2.43 ± 0.12 μm in width (n = 50). The spore wall is thick and measures 180 to 250 nm and consists of a clear endospore (130 to 170 nm) and an electron-dense, uniform exospore (50 to 80 nm). The polar filament is isofilar and has 15–16 coils. The well-developed polaroplast has a lamellated structure with thin lamellae. The ultrastructural features of Nosema leptinotarsae differ from those of other microsporidia infecting chrysomelids.
The black citrus aphid, Toxoptera aurantii Boyer de Fonscolombe (Hemiptera: Aphididae), an important pest of citrus species, feeds by sucking sap from plant leaves. It causes some leaf distortion and malformation of growing leaves and shoot tips. In this study, the eff ects of the botanical insecticide, palizin on T. aurantii and its parasitoid, Aphidius colemani Viereck (Hymenoptera: Brachonidae) were compared with the chemical insecticide, imidacloprid. Th e compounds were evaluated at maximum recommended fi eld concentrations: palizin 2,000 ppm, imidacloprid 500 ppm, water (as control) on adult aphids. Spraying was done with a 100-l engine Honda sprayer (GX120T1, 160T1, 200T) until run-off . Th e number of dead aphids was recorded 24, 48 and 72 hours aft er treatment. According to the results, statistically signifi cant diff erences were found between treatments (p ≤ 0.05). Twenty-four hours aft er treatment, imidacloprid was more eff ective than palizin in reducing the T. aurantii population. Palizin showed high effi ciency (95% mortality) 72 hours aft er treatment. However, at that time, there was no statistically signifi cant diff erence between the mean mortality percentages of imidacloprid and palizin. This shows that botanical insecticide, palizin can eff ectively control T. aurantii. Also, palizin caused low mortality (10.86%) on A. colemani while imidacloprid was more toxic (31.1% mortality). The results of the present study indicated that palizin can be used instead of chemical insecticide, imidacloprid in control programs of T. aurantii.
The western flower thrips, Frankliniella occidentalis (Pergande) attacks a large number of crop plants. The current insecticides have caused resistance in insects and have caused outbreaks of thrips. In many instances, alternative methods of insect management and natural products, offer adequate pest control and pose fewer hazards. Several species of minute pirate bugs of the genus Orius play a significant role in the biological control of a large number of thrips species, such as F. occidentalis. In this study, the insecticidal activity of four ethanolic plant extracts (Cercis siliquastrum L., Calendula officinalis L., Peganum harmala L., Melia azedarach L.) in integration with Orius horvathi (Reuter) were evaluated for controlling F. occidentalis. The present research aimed to find plant extracts with a good impact on F. occidentalis but which have fewer side effects on O. horvathi. The results showed that P. harmala extract can be considered compatible with the natural enemy for controlling thrips. When the predatory bugs O. horvathi, were released three days after P. harmala extract spraying, the integration was more effective. While the P. harmala plant extract plays an important role in thrips control, it is necessary to consider the specified time interval between the application of the P. harmala plant extract and the release of the O. horvathi predatory bugs. The ethanolic extract of M. azedarach caused a balance between the pest population and the natural enemy. This result is very important in an Integrated Pest Management (IPM) program because this ethanolic extract of M. azedarach had lower side effects on the natural enemy. This means that an integration of plant derived chemicals and the natural enemy, O. horvathi, can effectively control thrips.
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