PLANT PEST RESEARCH
Year:2018 | Volume:8 | Issue:2 |Papers Count:7

Increasing the production of products with greater diversity through mixed cultivation can be effective in improving ecosystem services and functions. One of the most important functions of the mixed crop system is the reduction in the population of pests and, consequently, the increase of crop yields. This research is aimed at effects of the intercropping system of soybean and corn on abundance of insect pests, pollinators and natural enemies, an experiment was conducted at the Agricultural Research field of Lorestan University, Iran. The experiment was carried out in the randomized complete block design on five treatments with four replications. The experimental treatments were sole soybean 100: 0, sole corn 0: 100 and 50: 50, 75: 25 and 25: 75 soybean: corn combinations, respectively. Different sampling methods such as pit fall trap, sieve, yellow and blue sticky cards, striking, sweep netting and local counting were applied to collect insects. Sampling was taken five times at interval of 14 days. Total of 7, 395 insects were collected during the sampling period belonging to 10 orders and 39 families. Results showed that the population of the collected insect including pests, pollinators and natural enemies were significantly influenced by the intercropping system. The maximum number of natural enemies and the minimum number of pests were also observed in the 50: 50 soybean: corn treatment. The maximum number of pollinating insects was found in 75: 25 soybean: corn treatment. However, the highest rate of pests and subsequently the lowest pollinating and natural enemy insects were found in the sole corn treatment. On the other hand, a negative relationship between natural enemies and pests as well as soybean yield and pest insects was obtained. The population of some pest families influenced by the system showed an increase in abundance of insects in intercropping system compared to that of the control treatment (i.e., sole cropping). Results showed that, some mixed treatments of soybean: corn proved to have more efficient biological control and more yielding than their sole cultures.

Asian citrus psyllid Diaphorina citri Kuwayama (Hem: Liviidae) is one of the most destructive citrus pests in tropical and subtropical regions. Asian citrus psyllid is a sap-sucking insect and could act as a vector for the serious citrus greening disease. Vector suppression is critical to reduce disease spread. In this research, the effect of kaolin powder was investigated on control of citrus psyllid in a randomized complete block design with 3 treatments including 3, 5 and 7% kaolin powder in Kerman province, during 2011 and 2012. The different concentrations were sprayed over the whole canopy of trees. Results showed that the percentage of the mortality of adults in the two years at concentration of 3%, 5% and 7% suspension of Surround WP ranged from 23.24 - 48.09, 53.47 - 85.49 and 62.23 -88.34%, respectively. Efficacy of 3, 5 and 7% suspension of Surround WP on citrus psyllid oviposition resulted in reduction of 22.86 - 49.69, 65.49 - 91.74 and 73.99 - 96.72%, respectively. The results showed that during two years of experiment, there was no significant difference between the two Kaolin treatments at 5 and 7%. Therefore, spraying citrus trees with processed kaolin, at a concentration of 5%, could significantly reduce the damage of the citrus psyllid.

The eggs and larvae of the Mediterranean flour moth, Ephestia kuehniella (Zell.), are widely used to rear parasitoids and predators for biological control programs. In this study, nutritional responses and digestive enzymes activities of the fourth instar larvae, as well as some immunological parameters of E. kuehniella, were studied on the diet containing casein and zein proteins under laboratory conditions. The fourth larval instar reared on diet containing casein had the highest relative rate of consumption (5.9 ± 0.2) and relative growth rate (11.3 ± 0.3). The highest and the lowest activity of lipase, tripcine, elastase, carboxypeptidase and aminopeptidase in larvae fed were on casein and zein proteins. In the immunological study, injection of tween and Beauveria bassiana (Balsamo) Vuillemin in larvae treated by casein protein significantly increased the total number of hemocyte and the number of granulocytes and plasmatocytes. This study indicated that the nature of the protein in the diet effects on physiological mechanisms of feeding and affect the immune response.

Effect of two types of mineral oils, EC and mayonnaise at two concentrations of 5ml/L and 7 ml/L, insecticidal soap Palizin Ò 2.5 ml/L, chlorpyrifos 1.5 ml/L, chlorpyrifos 1.5 ml/L+EC oil at concentration of 5ml/L, chlorpyrifos 1.5 ml/L+mayonnaise oil at concentration of 5ml/L and water as control was investigated on Unaspis euonymi as an important pest of boxwood, Euonymus sp. Six branches were sampled randomly from each treatment one day before spraying and 3, 7, 14 and 21 days after spraying and number of live insects were counted on 2 cm at the top of branch and 2 cm2 in the middle portion of underside of two leaves. Corrected mortality and mean comparison were determined by using the Henderson-Tilton formula and Tukey test at 0.05% probability level, respectively. In 2016, at 3 days after spraying on leaves, mineral oil EC at concentration of 7 ml/L with 67.9% mortality and chlorpyrifos 1.5 ml/L+EC 5 ml/L with 78.3%, 69.1% and 52% mortalities, respectively at 7, 14 and 21 days after spraying were more efficient treatments. On the branches, chlorpyrifos 1.5 ml/L+EC 5 ml/L was more efficient than other insecticides in all sampling days after spraying causing highest percentage of mortality. In 2017, chlorpyrifos 1.5 ml/L+EC 5 ml/L treatment was more efficient against U. euonymi when the leaves sprayed. Chlorpyrifos 1.5 ml/L+mayonnaise 5 ml/L at 3 days after spraying of the branches caused 55.7% mortality and at 7, 14 and 21 days after spraying, chlorpyrifos 1.5 ml/L+EC 5 ml/L with 69.7, 79.2 and 80.4% mortality was more toxic than other treatments. The results indicated that chlorpyrifos in combination with oil can be used in control programs of U. euonymi.

Sugarcane whitefly, Neomaskellia andropogonis Corbett (Homoptera: Aleyrodidae) is one of the important pests of sugarcane fields in Iran. In this study, the efficacy of two new insecticides including Sivanto Ò and Oberon Speed Ò was evaluated for controlling different life stages of whitefly on IRC99-02 and CP69-1062 sugarcane varieties under laboratory conditions. The concentrations of 20, 60, 100, 200, and 400 ppm of two insecticides were applied using leaf dipping method. The highest concentration of Sivanto Ò (400 ppm) caused 67.9% mortality on whitefly eggs in IRC99-02 variety; while Oberon Speed Ò did not show much ovicidal activity. Sivanto Ò effectively controlled the adult’s stage and the highest mortality percentage (90%) was observed at 400 ppm in IRC99-02 variety of sugarcane. While at the same concentration, Oberon Speed Ò caused 60 and 70% mortality in IRC99-02 and CP69-1062 varieties, respectively. Both insecticides were effectively controlled whitefly nymphs and pupae. Our results indicated that both of the insecticides had high toxicity on sugarcane whitefly. Also, parasitoid wasps were compatible with the insecticides and applied insecticides did not negatively affect their parasitism activity.

It is necessary to investigate side effects of insecticides on natural enemies of pests. In this study, toxicity of spirotetramat, acetamiprid, pirimicarb and flonicamid was investigated on parasitoid wasp, Lysiphlebus fabarum (Marshall). Furthermore, sublethal effect of the insecticides were evaluated on the functional response of the parasitoid to densities of 2, 4, 8, 16, 32 and 64 of third instar nymphs of Aphis fabae Scopoli under laboratory conditions. Residual bioassay method was used to determine the toxicity of the insecticides on parasitoid adults. For functional response assay, mated females (<12 h old) were exposed to LC25 of mentioned insecticides and distilled water as control in glass tube. Experiments were conducted in 15 replicates. The LC50 values of acetamiprid, pirimicarb and flonicamid were 22.5, 75.6 and 302.1 ppm, respectively. The mortality was 16% at three times the field rate (500 ppm) of spirotetramat. Functional response on control and insecticides treatments fitted the type II. Attack rate (a) in control, spirotetramat, acetamiprid, pirimicarb and flonicamid treatments were estimated 0.0689±0.01, 0.0480±0.01, 0.0272±0.06, 0.0475±0.01 and 0.0532±0.01 h-1 and handling time (Th) were 0.4322±0.04, 0.5148±0.06, 1.1004±0.18, 0.4558±0.08 and 0.4601±0.04 h, respectively. The results indicated that spirotetramat, flonicamid and pirimicarb had lower side effects on L. fabarum in comparison with acetamiprid and they are suitable candidates for controlling A. fabae in combination with L. fabarum.

In a study to investigate the fauna of Mirinae subfamily in Guilan province during 2017, many mirid species were collected and identified. Among collected species, Grypocoris fieberi Douglas & Scott, 1868 is reported as a new species for Iranian fauna. This species was collected on Cirsium sp. and weeds (Apiaceae) from Damash (36°43´N, 49°48´E.1737m) and SalanSar (36°55´N, 49°23´E.1703m). Collected specimens were deposited at the Natural History Museum of the University of Guilan, Rasht, Iran.