Journal Of Crop Protection
Volume:8 Issue: 3, Sep 2019

The genus Paratylenchus sensu lato includes members belonging to the genera Paratylenchus sensustricto (species with 10 to 40µm long stylet), Gracilacus (species with 40-120µm long stylet), Gracilpaurus (species having cuticular punctuations) and Paratylenchoides (species having sclerotized cephalic framework). Long stylet species become swollen and feed as sedentary parasites of roots, some feed from cortex of perennial host roots, but most species feed as sedentary ectoparasites on roots. In other words, species with stylet shorter than 40µm commonly feed on epidermal cells, whilst the species with longer stylet nourish primarily in cortical tissue, without penetration into the plant tissue. In general, pin nematodes, Paratylenchus spp. are parasites of higher plants with a higher abundance in the rhizosphere of trees and perennials. In present review, an attempt is made to document published information on the pathogenicity and damage potential of the pin nematodes to plants.

The quest for new sources of cheap and eco-friendly insecticide for insect pest management remains a major challenge facing cowpea farmers in many developing countries. In this study, the toxicity and biochemical mechanisms associated with the insecticidal efficacy of acetone and n-hexane extracts of Xylopia aethiopica (Dunal) and Senna occidentalis (L.) on Callosobruchus chinensis (L.) were investigated. The insecticidal efficacy varied with concentration, exposure time and extracts type. Acetone extract of X. aethiopica was less toxic (LD50 = 2.47%) than its n-hexane extract (LD50 = 1.39%) but with S. occidentalis, acetone extract was more toxic (LD50 = 0.73%) than n-hexane extract (LD50 = 1.37%). Acetone extract of both plants evoked a significant reduction in egg-laying and eclosion ability of adult C. chinensis compared to n-hexane extract except on cowpea pre-treated with acetone extract of S. occidentalis. Only the extracts of X. aethiopica reduced protein concentration compared to control. The activity of glutathione reductase and glutathione peroxidase was significantly reduced by both extracts of S. occidentalis while only n-hexane extract of S. occidentalis elicited a significant reduction in the activity of glutathione S-transferase and trehalase compared to other treatment levels. GC-MS analysis depicted Diisoocotyl phthalate (50.37%) and isomers of Aromandendrene (19.22%) as the main compounds in S. occidentalis and X. aethiopica respectively. Both botanical extracts also contained other insecticidal and insectifuge compounds in differential amounts. Overall, the findings demonstrated the potential of both botanical extracts, particularly acetone extract of S. occidentalis as alternatives to synthetic insecticide for controlling adult C. chinensis.

Effects of four vegetable host plants, artichoke, cabbage, potato and tomato on nutritional indices of the cotton leafworm Spodoptera littoralis (Boisduval) (Lep.: Noctuidae), were studied under laboratory conditions (25 ± 1 °C, 65 ± 5% RH, with a 16: 8 L: D photoperiod). Fourth instar reared on tomato showed the highest approximate digestibility (AD) (90.406 ± 1.125%) and efficiency of conversion of ingested food (ECI) (30.249 ± 4.128%). The highest values of efficiency of conversion of digested food (ECD) and ECI of fifth instars (38.663 ± 4.34 and 20.083 ± 1.581%, respectively) were on artichoke and the lowest of both values on cabbage (ECD: 6.314 ± 1.128 and ECI: 5.448 ± 1.052%).The 3rd to 6th instars as a whole showed the highest ECD and ECI values on tomato (23.412 ± 2.252 and 19.845 ± 1.798%, respectively). However, the highest and lowest values of consumption index (CI) were on cabbage (33.943 ± 2.669) and tomato (6.145 ± 0.578). The highest values of relative consumption rate (RCR) and (AD) were obtained on cabbage (1.49 ± 0.109 mg/mg/day and 86.431 ± 1.141%, respectively). The results of nutritional indices and the cluster analysis indicate that tomato was nutritionally the most suitable food for S. littoralis.

Five fungicides, with active ingredients azoxystrobin, imazalil, thiabendazole, azoxystrobin + difenoconazole and fludioxonil + difenoconazole, were tested against two isolates of Fusarium solani and two isolates of F. oxysporum, causing potato dry rot in Mashhad region. PDA media amended with the fungicides significantly inhibited the mycelia growth of all Fusarium isolates incubated at 25 °C for 7 days; however only Imazalil and Thiabendazole completely stopped the mycelia growth of all fungal isolates even at their lower concentration (40 and 5ppm respectively). The mean penetration of F. solani FPO-67 and F. oxysporum FPO-39, the more virulent of the four isolates, after 21 days of incubation at 25-27 °C indicated that imazalil and thiabendazole at concentrations of 1.5 and 2/1000, completely inhibited the penetration of F. oxysporum FPO-39 into potato tubers, but in the case of F. solani FPO-67 all treatments (1, 1.5 and 2/1000) significantly reduced the development of dry rot compared to untreated control. In natural condition, tuber treatment with Imazalil and Thiabendazole (2/1000), prior storage, reduced F. solani FPO-67 development by 68 and 71.69% respectively. According to the results, these fungicides could play a role in integrated pest management against tuber-borne fungal pathogens.

The subfamily Pangoniinae including the species Pangonius pyritosus Loew, 1859 as well as the species Chrysops hamatuus Loew, 1858 (Chrysopsinae) are recorded for the first time for Iranian fauna. Diagnostic characters besides supplementary photos of the new records are provided.

To assess the variability of Macrophomina phaseolina (Tassi) Goid, the causal agent of charcoal rot of Sesame, sixty isolates recovered from ten geographic regions, were analyzed using inter simple sequence repeat (ISSR) and universal rice primer (URP) markers. Isolates were grouped into eight clusters at 78% genetic similarity level. Our results showed that the five ISSR primers produced 105 bands of which 77.11% were polymorphic and eight URP-PCR primers generated 135 bands of which 66.84% were polymorphic. These methods showed a considerable genetic diversity among Iranian isolates, but no correlation was found between genetic diversity and geographical origins of the isolates. Analysis of molecular variance revealed that a large proportion of genetic variability resulted from the differences among isolates within regions. The findings of this study demonstrated that the low-genetic differentiation (GST) and high gene flow (Nm) among populations had a significant effect on the emergence and evolutionary development of M. phaseolina.

Functional response is an important behavioral characteristic of prey-predator interactions that can be utilized for assessing impact of natural enemies. In this research, the functional response of Nabis pseudoferus Remane females was examined to the third-instar larvae of Tuta absoluta (Meyrick) which were exposed to LC30 (2.03 × 104 conidia/ml) values of Metarhizium anisopliae (Metschnikoff) Sorokin isolate DEMI 001. Six densities of the prey (1, 2, 4, 8, 10 and 16) were exposed to the predator (0, 24, 48 and 72 h) after inoculation. N. pseudoferus exhibited a type II functional response to prey density in all treatments, indicating that predation increases asymptotically to a satiation level. The highest and the lowest attack rates (a) were 0.1052 ± 0.0440 and 0.0509 ± 0.0133h-1 for 48h and 72h post-infection treatments, respectively. Maximum theoretical predation rate (T/Th) was estimated 10.96 in control. Our results suggest that M. anisopliae and N. pseudoferus, can be a useful combination in pest management of tomato leaf miner, although it must be confirmed in field condition.

In this study the cellulytic activity of different species of Iranian Trichoderma isolates including Trichoderma harzianum (NAS-H101), T. aureoviride (NAS-AV106), T. pleuroticola (NAS-P109), T. longibrachiatum (NAS-L110), T. ghanens (NAS-K108), T. virens (NAS- Vi114), T. atroviride (NAS-A113) and T. atroviride (NAS-A112) was studied. The extracellular protein concentration of these isolates was determined by the dye binding method of Bradford. The molecular weight of cellulase enzymes was studied using SDS-PAGE. The lowest extracellular protein production was observed in NAS-K108. The highest Endo and Exo-glucanase activity were observed in NAS-L110 and NAS-A113, respectively. The SDS-PAGE profiles had several enzyme bands such as cellobiohydrolases, endoglucanases and β-glucosidases. The NAS-K108and NAS-P109 had both enzyme bands of CBH I and CBH II, but other isolates had only a sharp enzyme band correlated to CBH I or CBH II. The highest synergy was observed in FPase of NAS-A112, that contained a large amount of Cel 6A (CBH II) and a minor amount of Cel 7B (EG I). The results indicated that NAS-A113 overproduces cellulases, ß-glycosidase, and the extracellular enzymes, which suggest that this species might be utilized as a biological agent and or a source of enzymes for cellulose degradation in colloidal cellulose.

In the present study, the toxicity of three oxygenated monoterpenes, viz., (R)-carvone, (R)-camphor and (1R, 2S, 5R)-menthol was evaluated against the adults of the peach fruit fly, Bactrocera zonata (Saunders). Effects of these monoterpenes on oviposition, adult longevity and ovarian development have also been studied. The tested compounds revealed strong toxic effect against the adults of B. zonata. Nevertheless, (-)-carvone showed higher insecticidal activity than (1R, 2S, 5R)-menthol and (R)-camphor. Moreover, the tested monoterpenes induced significant reduction in female longevity at 20 and 50 mg/kg compared with control, with (-)-carvone being the most effective monoterpene. In addition, egg deposition was completely inhibited when the adults were treated with (-)-carvone at 20 and 50 mg/kg, and (1R, 2S, 5R)-menthol and (R)-camphor at 50 mg/kg. Histological studies indicated that monoterpenes induced delay in the development of ovarioles of females that fed on artificial diet treated with 20 and 50 mg/kg of compounds. Changes, such as empty egg chambers; constricted germarium, vacant spaces between ovarioles and failure of oocyte formation were observed.

Deep understanding of biological and behavioral characteristics of trichogrammatid wasps, helps us for better and more efficient rearing of these parasitoids. In the current study, Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) was reared on Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) for several generations and the effect of long-term rearing of the parasitoid on some of its attributes like parasitism capability, emergence rate, sex ratio, and wingless rate of adults was determined in both laboratory and insectarium conditions. The laboratory investigation showed that long-term rearing decreased fitness of the parasitoid, so that, parasitism rate and adult emergence rate decreased. By contrast, sex ratio and number of wingless individuals increased with increasing generations. Our results in insectarium were a little different. However, adult emergence rate had significant difference and trichocards quality decreased with increasing generations. The sex ratio in different periods had no significant difference. Furthermore, there was no significant difference in wingless rate in different rearing time periods. Accordingly, the parasitoid’s fitness was affected by number of generations in both conditions. Although, mass rearing under laboratory condition provided wasps with more desired traits than those reared in insectary, both decreased fitness of T. brassicae when number of generations increased.

Western flower thrips, Frankliniella occidentalis (Pergande), an important pest in rose greenhouses, has several generations per year, and in addition to direct feeding damage to rose flowers it also transmits tospoviruses. Because of resistance to insecticides, alternative strategies are needed to manage this pest, including trapping. In this study, trapping by sticky traps of two different colours (blue and yellow) was experimented at three different heights (at canopy level, and 20 cm above and below canopy level) on two rose cultivars (Red one and Avalanche). The numbers of trapped thrips were counted after five days. The number on the blue sticky traps, regardless of their height of placement and type of cultivar, was significantly higher than that on the yellow traps. Number of thrips on blue traps at 20 cm above the canopy was significantly higher than on blue traps at the other levels in both cultivars. In contrast, the number of thrips that were trapped in yellow sticky tarps in various heights as well as cultivars was not significantly different.