PLANT PEST RESEARCH
Year:2018 | Volume:7 | Issue:4 |Papers Count:7

The lesser moth, Batrachedra amydraula is one of the most important pests of Dates. The aim of this study was to investigate the efficiency of Bacillus thuringiensis to control this pest in Date palm plantation condition. Krustaki bacterial isolate was used. The split plot design was used to conduct the research. Main plots consisted of three times of treatments including same time, three days and a week after the appearance of the pest. Sub plots were three different concentrations medium, average and maximum including One-tenth, equal and ten times of LD50 given 2 days and continued for a week.The experiment consisted of four replicates on a Sayer Date palm tree. A chemical control (Diazinon insecticide) and a treated without the chemical and biological control was considered as control group.Percentage of damaged fruit as the symptoms of biological pest activity were been sampling from mid-April once every two weeks of treatment. The results showed that there were significant differences between treatments, so that the maximum infection was recorded on minimum concentration at 3 and 7 days after the lesser moth appearance. The minimum infestation was recorded on maximum concentration and there were no significant differences between the three different times of release. The lowest average growth rate and the highest average reduction of injury growth rate were recorded on maximum concentration and coincided with the pest emergence treatment. The highest performance control was recorded on the maximum concentration coincided with the emergence.

Botanical insecticides are one of the tools in integrated pest management programs. It is necessary to investigate their effect against pests and their side effects on natural enemies of pests. In this research, toxicity of two botanical insecticides, Dayabon Ò and Palizin Ò were investigated against third instar nymphs and adults of Aphis fabae Scopoli as well as pupal stage of its parasitoid wasp, Lysiphlebus fabarum (Marshall). Furthermore, effect of the insecticides were evaluated on the functional response of L. fabarum. All experiments were done under laboratory conditions. These insecticides were highly toxic for third instar nymphs of A. fabae with LC50 values of 750.2 and 636.3 ppm for Dayabon Ò and Palizin Ò, respectively. The LC50 values of the insecticides were 1302.04 and 1062.8 ppm, respectively, for adults. Mean adult parasitoid wasp emergence were 86.08 ± 3.2, 89.74 ± 2.55 and 91.33 ± 2.03%, respectively, for Dayabon Ò, Palizin Ò and control treatments at pupal stage.The insecticides had no adverse effect on fecundity of emerged females. According to International Organization for Biological Control, Dayabon Ò and Palizin Ò were classified as harmless insecticides.The results revealed the type II functional response in all experiments. Attack rate (a) of L. fabarum in control, Dayabon Ò and Palizin Ò treatments were 0.075, 0.050 and 0.056 h-1 and handling time (Th) were 0.459, 0.515 and 0.482h, respectively. There were no differences in the functional response parameters between the treatments. These results suggest that Dayabon Ò and Palizin Ò are suitable candidates for control of A.fabae in combination with L. fabarum.

Sunn pest, Eurygaster integriceps Puton (Hem: Scutelleridae) is one of the most important pests of wheat in Iran, which causes considerable annual quantitative and qualitative damages to the crop.In order to evaluate the resistance of wheat genotypes to the nymphs of Sunn pest, 25 endemic wheat genotypes were studied at the Agricultural Research Station, University of Kurdistan. The experiment was carried out in a random complete block design with three replications. The analysis of variance showed significant differences among the genotypes for the mortality of Sunn pest nymphs, the weight increase of the adults and the percentage of damaged seeds. In addition, the results of correlation analysis showed that there was a positive significant correlation between the percentage of damaged kernel and covering kernel by glume and glomels (P<0.01). However, there was no significant correlation between percentage of damaged kernel and other traits such as glume hairless, glume status and awn status. But the results showed that there was a negative and significant correlation between number of seeds per spike and total weight of insects (P<0.01).Over all, using a cluster analysis by Ward method and based on Euclidean distance, the genotypes were classified in three groups as: resistant, partly resistant and relatively susceptible.

Pest monitoring is a key component of integrated pest management program in agricultural ecosystems, so that prior to deciding on the use of pest management practices, appropriate information on pest density should be available. In this study, the efficacy of yellow sticky cards and D-vac method was investigated to determine the most practical method for sampling of some wheat pests including, Oscinella frit L., Chlorops pumilionis Bjerk. (Diptera: Chloropidae), Cephus pygmaeusL. (Hymenoptera: Cephidae) and Psammotettix alienus Dahlb. (Hemiptera: Cicadellidae).This study was conducted at Zarghan region of Fars Province, during 2013 and 2014.Taylor power law was used to determine the spatial distribution of the pests. In order to determine the optimal sample size, the sequential sampling with constant accuracy of 0.2 and Green's method were used. In yellow card sampling method, C. pygmaeus had a clumped distribution and P. alienus, C.pumilionisand O. frit had a random distribution. All four pest species collected with the D-vac method had a random distribution pattern. The results showed that the number of required sampling units decreased with increasing population density of the pests. Whenever the average density of the C. pumilionis, O. frit, C. pygmaeus and P. alienus in each yellow card is one, the number of required samples with a precision level of 0.2 would be 21, 27, 42 and 48, and when the average density of these pests in each unit of the D-vac method is one, the number of required samples would be 19, 13, 33, and 39, respectively. Results showed that based on precision and efficiency considerations, the most practical sampling method for monitoring these four pests is using yellow sticky cards. The results of this study can be useful in integrated pest management programs of these four pests in wheat fields.

Streblote siva (Lefebvre) (Lepidoptera: Lasiocampidae) is one of the important potential pest of Conocarpus erectus L., Ziziphus spina-christi (L.) Willd. and Acacia ampliceps Maslin at Bushehr, Khuzestan and Hormozgan provinces. The life table parameters of S. siva was studied on C. erectus and Z. spina-christibased on the age-stage, two-sex life table at 27±2 ºC, 65±5% RH, and a photoperiod of 12: 12 (L: D) h under laboratory conditions using TWO SEX-MS Chart program. The mean and standard errors of the life table parameters were estimated using paired bootstrap method with 200, 000 bootstraps.Results showed that S. siva completed its development on every two hosts. The intrinsic rate of increase (r) of S. siva on C. erectus and Z. spina-christi was 0.081 and 0.068  d-1. The finite rate of increase (l) revealed that the population of S. siva increased as 1.08 and 1.06 times per day on C. erectus and Z. spina-christi, respectively. The mean generation time (T) was 56.24 and 62.74 days on C. erectus and Z. spina-christi, respectively and this difference was statistically significant. The net reproductive rate (R0) of S. siva was 94.83 and 62.93 offspring, respectively. According to the results, it seems that C. erectus is a more suitable host plant for this pest.

The spherical mealybug, Nipaecoccus viridis (Newstead) is one of the major citrus pests with economic importance in the world which also occurs in southern Iran, including Khuzestan province. In this research, prey stage preference and functional response of the coccinellid Hyperaspis politaWeise feeding on N. viridis were studied at 30 ± 1oC, 65 ± 5% RH and a photoperiod of 14: 10 (L: D) h. Results indicated that the eggs of mealybug were preferred more than any other stages by most stages of H. polita, whereas adult females were less preferred.Results of logistic regression for 4th larval stage, adult female and adult male of ladybeetles by feeding on mealybug eggs, the preferred stage, revealed functional response type II, II and III, respectively. The searching efficiency (a) for 4th instar larvae and adult females were 0.2553 and 0.1983 h-1, respectively, using Rogers equations. Constant coefficient (b) for adult males was estimated to be 0.00405. The minimum handling time (Th) was estimated to be 0.0881 for 4th instar larvae and maximum was 0.3101 for adult males of ladybeetles. The maximum theoretical predation rate (T/Th) was calculated as 298.51 eggs/day by 4th instar larvae and minimum was 77.39 eggs/day by adult males. According to our results, it seems that H. polita has the potential for biological control of N. viridis. Nevertheless, additional field investigations of H. polita and comparison to other available predators would be necessary.

Lysiphlebus fabarum (Marshall) is an important endoparasitoid of the black bean aphid, Aphis fabaeScopoli. In this study, sublethal effects of the field recommended concentration of deltamethrin (0.5 ml a.i./l) were evaluated on the parasitoid in a growth chamber at 21±1°C, 60 ± 5% RH and a 16: 8 h (L: D) photoperiod. One-day-old mummies were exposed to the insecticide via dipping method.Distilled water was used in the control treatment. The demographic parameters of emerged adults from treated mummies were studied. The results showed that the field recommended concentration of deltamethrin negatively affected biological and the stable population parameters, e.g., number of eggs laid(mummified aphids), emergence rate of adults and longevity, the intrinsic rate of increase (r) and finite rate of increase (l) and the mean generation time (T). Overall, the results of this study indicated that deltamethrin caused deleterious effects on the parasitoid and semi-field and field tests seem to be necessary.