PLANT PEST RESEARCH
Year:2016 | Volume:6 | Issue:2 |Papers Count:7

Population density, sampling program and spatial distribution pattern of the eggs and larvae of Callosobruchus maculatus on cowpea (var. Parastoo) were determined in Tehran region. Bean pod was selected as a sample unit and the reliable sample size with maximum relative variation of 20% was obtained 50. Taylor's power law and Iwao's patchiness regression, Index of dispersion and Lloyd's mean crowding methods were used for determining the spatial distribution pattern of eggs and larvae of the pest. The relationship between length and diameter of pods with number of laid eggs was determined using linear regression. There was significant positive relationship between number of eggs and the length of pods. The relationship between number of eggs and diameter of pods was also significantly positive. There was no significant relationship between number of larvae and length/diameter of bean pods. Moreover, the spatial distribution pattern of immature stages of pest using Taylor's method, index of dispersion and Lloyd's mean crowding was aggregated. Occurrence of the pest in field was observed early summer and irregular population fluctuation was recorded during growing season.

Lesser mulberry pyralid, Glyphodes pyloalis Walker is a serious monophagous pest of mulberry in northern Iran. In this study, life table parameters of G. pyloalis were determined during 2014 and 2015 under field conditions in Rasht, Guilan, Iran. Data were analyzed based on an age-stage, two-sex life table. The results showed that total immature developmental time was significantly different for two generations in 2014, whereas, there was no significant difference among three generations of G.pyloalisin 2015 under field conditions. In addition, total preoviposion period, oviposition period and fecundity of adults in first generation were significantly higher than second generation in 2014. The intrinsic rate of increase (r) of G. pyloalis in first generation (0.093 day-1) was significantly less than the second generation in 2014. Whereas, the net reproductive rate (R0), gross reproductive rate (GRR) and the mean generation time (T) were significantly higher in first generation than second generation in 2014. Furthermore, ther, R0 and T values ranged from 0.081 – 0.093 day-1, 14.66 – 24.62 offspring and 32.91– 33.32 days among three generations in 2015. Because of different life table parameters of the pest generations under field conditions, the results of present study confirmed that collection of life table data under field conditions is invaluable for understanding the seasonal population dynamics of G. pyloalis to construct an effective pest management program.

Effect of Kaolin on second instar larvae of Tomato leaf miner moth, Tuta absoluta (Meyrick) was investigated. Effect of various concentrations (0, 2.5%, 5% and 7.5%) of Kaolin was tested on second instar larvae of tomato leaf miner. Kaolin was sprayed in a completely randomized design with five repetitions on each tomato plant with height of about 30 cm. Then, ten second instar larvae of tomato leaf miner were released randomly on tomato leaves. After 72 hours, data in the mortality of larvae, escaped larvae and feeding amount (in cm2 and % of eaten (were taken. The feeding amount was measured by leaf level device. Data were analyzed with SAS software. Based on the results, different concentrations of Kaolin, had significant repellency properties and mortality on larvae. The mean of larval repellency calculated for concentrations of Kaolin %2.5, %5, %7.5 and control were (3.00±0.39), (3.40±0.39), (3.00±0.39) and (1.60±0.39), respectively. In average less than 20% mortality was observed for various concentrations of Kaolin. In contrast, none of the concentrations of Kaolin had significant effect on feeding amount of the second instar larvae of pest.

The objective of the current research was to evaluate the effect of the entomopathogenic fungus, Beauveria bassiana (Ascomycota, Hypocreales), on foraging behaviour of the parasitoid wasp, Aphidius matricariaeHaliday (Hym.: Braconidae), on whole eggplant under microcosm conditions. A Y-tube olfactometer experiment showed the presence of the fungus caused avoidance of the parasitoid and conversely, its attraction towards the empty arm. Although most ofA. matricariae significantly moved towards clean air (control), but a few were attracted to damaged eggplants infested with the sporulating aphid cadavers. Moreover, no-choice test for the effect of sporulating aphid cadaver on foraging behaviour of the A. matricariae revealed that the presence of the fungus significantly reduced the number of ovipositional attempts. In choice test, the parasitoid spent more time on damaged plants than on intact ones. The presence or absence of the fungus had no impact on allocation time of the parasitoid in an aphid colony. The results indicated that the parasitoid wasp, A. matricariae, was able to distinguish the entomopathogenic fungus and avoided entering the infected aphid colony. Nevertheless, when the parasitoid entered to an infected colony, it avoided contacting with the fungus or ovipositing. The results indicated that the released chemical cues of eggplant and also those of the entomopathogenic fungus, B. bassianaisolate EUT116, play an important role in the foraging decision making and also for increasing its fitness to control the green peach aphid.

The Greater Wax moth, Galleria mellonella Lin. is one of the most important pests of stored products and beehives. Chemical pesticides are used for its control. Inappropriate using of pesticides caused serious environmental problems and also chronic effects on human health. Pest damage is reduced by the optimum use of these materials. The purpose of optimum use is selection of the correct pattern and applying appropriate methods for use of toxins. So in this study response surface method was used in order to determine optimal points to achieve maximum mortality with minimum dosage.The effect of factors such as temperature (25-35oC), humidity (70-80 %) and the dosage (200-500 mL) on the mortality of fifth instar larvae of greater wax moth was evaluated. The experiments were performed according to Central Composite Design. Using the method, the maximum mortality was determined 7.6 fifth instar larvae of greater wax moth at 25oC, humidity 70% and 200μl of deltamethrin in 1000 ml of water. The result showed that temperature and dosage had significant effect on mortality of fifth instar larvae of Greater Wax moth.

Almond, Prunus dulcis M. (Rosaceae) is one of the major orchard crops in Iran, which has main role in almond production in the world. One of the most important almond pests is bud gall mite, Acalitus phloeocoptes (Nalepa) with symptoms of buds dieback on two years old branches. In order to find out some important points in the life cycle of mite such as development times of immature, longevity and fecundity in Khorasan-e-Razavi Province, this study was carried out in almond orchards during 2013-2014. Laboratory studies were conducted at 25 ± 0.5°C, %60±5 relative humidity with 16: 8h L: D. Mean development time of females and males were 16.8 ± 0.020, 16.57 ± 0.25 days, respectively. The female life time fecundity was 33.3±0.35 eggs. Female mean longevity was 15.57±0.25 while that of male was 10.53±0.12 days. A female generation time was 29.35-37.8 days while it took 28.85-36.6 days for male. Mites cause gall in the host plant bud scales and prevent their growth. The results showed that bud gall mite overwintered as second nymphal stage (protogyne) in galls and the first adults begin to move out of the galls in mid-March. Field studies showed that different developmental stages except for adults spent their life inside the gall. Swelling of buds's tissue occurred simultaneously with the beginning of the host's growth. Female oviposited from the early June to late May in the first and second years of study. The development times of immature stages were also determined. This pest was found in Sabzevar, Kashmar, Neyshabur, Torbat-e Jam and Torbat –e-Heydarieh. Meanwhile our investigation showed that, this mite causes gall on the plum trees (Prunus domestica) and apricot (Prunus armeniaca) too.

Study of the effects of genetically modified plants on non-target arthropods, is one of the most important research on transgenic plants safety. These plants are able to affect on natural enemies, directly and/or indirectly. So, in this study, the effect of feeding on Bt cotton and prey (Bemisia tabaci Gennadius) reared on Bt cotton was determined on predatory bug, Macrolophus pygmeus Rambur. Four diets including Bt-cotton+Bemisia tabaci (first group), non Bt-cotton+Bemisia tabaci (second group), Bt-cotton (third group), non Bt-cotton (forth group) were used in this experiment. The results showed that Bt-cotton significantly affected development time and fecundity of the predator. Developmental times of nymphs in the first, second, third and fourth groups were estimated to be 19.85±0.32, 16.08±0.24, 29.42±0.45 and 23.11±0.23 days, respectively. In addition, mean number of eggs laid in the non Bt-cotton +Bemisia tabaci treatment were significantly more than other groups (32.778±0.97), although no significant differences were found on fecundity between Bt-cotton and non Bt-cotton treatments. According to the obtained results, the Bt-cotton potentially could have negative effect on the biological parameters of M. pygmeaus severely and applying transgenic plants as one of integrated pest management agent, needs still more experiments and attentions.