Journal Of Crop Protection
Volume:11 Issue: 2, Jun 2022

The present work was undertaken to compare the insecticidal activity of two Rosmarinus officinalis L. (Lamiaceae) essential oils chemotypes from the Mediterranean region against different life stages of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) in constant environmental conditions. The essential oils were extracted by hydrodistillation and analyzed by the gas chromatography-mass spectrometry technique (GC-MS). α-pinene (29.42%), camphene (24.62%), and camphor (20.95%) were obtained as the majority compounds in the essential oil of R. officinalis from Algeria, as well as the main essential oil compounds of R. officinalis from Spain were α-pinene (25.62%), 1,8-cineole (21.06%) and camphor (18.39%). Ovicidal activity of oils was studied by topical application, while adulticidal and larvicidal activities were assessed by fumigation and ingestion, respectively. R. officinalis from Spain presented the highest toxic activity against eggs (78.33% inhibition), young larvae (LC50 = 3.40 mg/ml) and adults (LC50 = 0.17 mg/ml). On the other hand, R. officinalis from Algeria presented lower egg hatching inhibition with 60% and fewer fumigant and antifeedant activities (LC50 = 0.30 and 4.97mg/ml for adults and young larvae, respectively). The results of this study indicated the efficacy of rosemary essential oil as an alternative to synthetic insecticides in a postharvest treatment program for the control of E. ceratoniae.

Increasing insect resistance to the high toxicity of organophosphates and other conventional insecticides highlights the importance of developing and identifying alternative chemicals to successfully manage insect pests, including the striped rice stem borer (SRSB) Chilo suppressalis (Walker). SRSB is one of the most serious pests in paddy fields worldwide, especially in northern Iran. The present study was conducted to determine the efficiency of six insecticides viz., diazinon 10 G (Bazodin) 15 kg/ha; fipronil 0.2 G (Regent) 20 kg/ha; chlorantraniliprole 0.4 G (Ferterra) 12.5 kg/ha; thiamethoxam 25 WG (Actara) 0.2 kg/ha; flubendiamide 20 WG (Takumi) 0.9 kg/ha; dinotefuran 20 SG (Starkle) 0.75 kg/ha against SRSB. The experiments were carried out in randomized complete block design with three replications in experimental paddy fields of Rice Research Institute of Iran, Guilan province, 2018 and 2019. Chlorantraniliprole had the lowest dead heart and whitehead percent and the greatest efficiency against SRSB, followed by flubendiamide and dinotefuran. Our results suggested that chlorantraniliprole, flubendiamide, and dinotefuran can replace diazinon and fipronil in paddy fields. Furthermore, a new equation has been proposed for the calculation efficiency of insecticides based on the SRSB damage percent.

The Indian meal moth, Plodia interpunctella (Hubner), is one of the main economic pests of stored products, including dried figs, in Iran and the world. In this research, the effect of different doses of gamma radiation (50-1000 Gy) and temperature (20-35 ± 1 °C) was investigated on the life stages of P. interpunctella. The results showed that P. interpunctella eggs and adults exposed to gamma radiation (50 Gy) died after a short time. Therefore these stages are so sensitive to gamma radiation and were not used for further investigation on a combination of gamma radiation and temperature. In all temperatures, the survival period of larvae significantly decreased with increased radiation doses, especially at 600, 800, and 1000 Gy. Similarly, at 33 and 35 °C, low gamma radiation doses (50, 100, and 200 Gy) caused early larval mortality. In all temperatures, doses of 800 and 1000 Gy of gamma radiation resulted in 100% mortality of pupae; thereby, adult emergence declined to zero. However, in lower radiation doses of 50, 100, and 200 Gy and at 35 °C, the pupal mortality increased to 70, 70, and 83.33%, respectively. Results are promising for the integrated management of P. interpunctella on dried figs in storage.

The black bean aphid, Aphis fabae Scopoli, is a critical pest feeding on various host plants. This study was conducted to investigate the effect of kaolin on A. fabae and one of its natural enemies, Hippodamia variegata (Goeze). The investigation was carried out in Barkat broad bean cultivar during 2017-2019 in field and greenhouse conditions in Karaj, Iran. The experiment was conducted as a factorial randomized complete block design with four replications. Kaolin (Sepidan® WP %95) was tested at 3, 6, and 9%, and the sampling was carried out one day before application and three, six, nine, twelve, and fifteen days after application. As soon as the insects settled, kaolin foliar application began. The laboratory tests on black bean aphid showed the highest efficiency of kaolin 9% at 12 days after application, while the least was three days after application with kaolin 3%. Field trials indicated the highest efficiency of kaolin 9%, 9 days after application. Kaolin 9% caused the highest detrimental impact on H. variegata 15 days after foliar application.

Among the best ways to control chickpea wilt disease caused by Fusarium oxysporum f.sp. ciceris (Padwick) is the use of resistant genotypes. Accordingly, the resistance of forty-one different chickpea genotypes was evaluated, over two growing seasons, under natural field infection conditions. Follow-up experiments revealed that most chickpea genotypes exhibited typical yellowing and wilting symptoms associated with wilt disease. Quantifying disease incidence at different stages revealed considerable variation among chickpea genotypes ranging from 28.13% to 66.15%. Among the genotypes tested, five can be qualified as resistant and sixteen genotypes moderately resistant, while eighteen were susceptible and only two can be considered very susceptible to Fusarium wilt. The results show that disease severity increases over time, correlated with disease incidence, and vice versa. Furthermore, grain yield was negatively affected by disease incidence; however, the disease did not affect the hundred-grain weight. The genotypes characterized by resistance to wilt and combined with productive performance can be used as such or integrated into breeding programs to develop Fusarium wilt-resistant varieties.

The present research aimed to study the insecticidal activity of four ethanolic extracts of Cercis siliquastrum L., Calendula officinalis L., Peganum harmala L., Melia azedarach L. against Frankliniella occidentalis (Pergande) as well as hatching time and hatching rate of Orius horvathi (Reuter). The results revealed that the extracts had no significant effect on the hatching time of the predatory bug. The result showed concomitant use of the extracts with releasing eggs of the O. horvathi could control thrips effectively. The lowest (73.66 ± 7.01%) hatching rate belonged to P. harmala, indicating concomitant use of P. harmala extract with releasing eggs of O. horvathi can cause effective control of adult thrips. Moreover, concomitant use of C. siliquastrum, C. officinalis extracts with releasing eggs of O. horvathi can control immature thrips effectively.

Orobanche crenata, an obligate holoparasite, causes severe damage to faba bean grown in the Mediterranean region. A greenhouse experiment was conducted to determine and compare the potential of salicylic acid (SA), and acetylsalicylate (AcSA) used as seed soaking (0.5-1.5 mM, each) or foliar spray (2-6 mM, each) to increase faba bean tolerance to Orobanche crenata infection. Under the challenge of Orobanche infection, the application of SA or AcSA enhanced the growth of faba bean plants by improving their viability, height, and fresh and dry weight. SA and AcSA reduced the growth of parasite tubercles and retarded their development to emerged spike, the most harmful stage. AcSA was more effective than SA in increasing faba bean tolerance to O. crenata infection, and seed soaking showed the greatest effect. At 110 days of sowing, soaking seeds in 0.5 or 1 mM AcSA completely prevented the death of infected plants and increased the weight of plants by 22 and 67%, respectively, and pod weight/plant by 512 and 442%. Moreover, these two treatments greatly reduced Orobanche growth, and complete inhibition of tubercles and emerged spikes occurred by soaking seeds in 0.5 mM AcSA. Orobanche infection greatly increased phenolic content and antioxidant activity in the host tissues, but their levels tended to reduce by all salicylate treatments. The results suggest the great potential of soaking host seeds in AcSA, the inexpensive commercial form of SA, can enhance plant resistance against Orobanche parasite.

Few studies have investigated the efficacy of natural enemies against pests in hydroponic farming. We aimed to determine the effectiveness of two predators Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), and Macrolophus pygmaeus Rambur (Hemiptera: Miridae), for controlling Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in hydroponic cultures of Batavia lettuce. Both C. carnea and M. pygmaeus were released weekly with spot treatment: 10-20 individuals /m2 and 0.25-5 individuals/ m2/release, respectively. One of the more substantial conclusions from our current study is that C. carnea and M. pygmaeus highly reduced the F. occidentalis larvae and adults (45.85 and 60.91%) over the control treatments. The efficiency of M. pygmaeus was higher than that of C. carnea. The population of F. occidentalis decreased from 8.75, 7.75, and 7.5 individuals /leaf in control to 8.25, 7.0, 6.25, and 3.5, 3, and 2.5 individuals/leaf in the C. carnea and M. pygmaeus, respectively in all three planting cycles. Results also showed that in control and M. pygmaeus, the variation was only significant between cycles 1 and 3. While the C. carnea group showed a significant difference between cycles 1 and 3 and 1 and 2. Results also indicated that M. pygmaeus was more effective than C. carnea as a biocontrol agent against the larvae and mature F. occidentalis. Thus, using M. pygmaeus and C. carnea to manage the thrips damage is advised.

The present study investigated the effect of allatostatin (Ast) on the adult female reproductive system of the greater wax moth, Galleria mellonella (L.). At first, different concentrations of Ast in the brain- SOG, midgut, ovaries, and fat body of 5 days old adult females were confirmed. Moreover, it was shown that the highest concentration of Ast was observed in brain-SOG. Daily injections of Ast decreased ecdysteroid concentration in the hemolymph and ovaries. Ast injection decreased the expression level of vitellogenin (Vg) genes. Furthermore, it reduced oocyte size. These results showed that Ast has a regulatory role in the reproduction of G. mellonella female.

Beet curly top Iran virus (BCTIV) and Beet curly top virus (BCTV) are responsible for the curly top disease in sugar beet Beta vulgaris L. and many other plants. Mixed infection by BCTIV and BCTV in sugar beet plants results in a synergistic interaction, with more severe symptoms than plants infected by either virus, accompanied by an increase in BCTIV and a decrease in BCTV titers. Interaction of the Replication associated protein (Rep) with the nonanucleotide motif within the origin of replication is crucial for the replication of the geminivirus genome. Using an in silico approach, we investigated the possible contribution of the interaction between Rep and the nonanucleotide motifs in the interference between BCTIV and BCTV in mixed infections. The physicochemical characterization of both Reps was performed, and their secondary and tertiary structures were predicted by SOMPA tool and I-TASSER server, respectively. Then, the binding affinity of each Rep towards cognate and non-cognate viral nonanucleotide motifs was assessed using Docking simulations. Cluster analysis of HADDOCK revealed that the total binding energy of BCTV Rep toward its cognate nonanucleotide motif was lower than for the BCTIV complex, confirming a higher affinity of BCTV encoded Rep for its nonanucleotide motif. Interestingly, the BCTIV Rep showed the highest affinity for the nonanucleotide motif of the non-cognate BCTV nonanucleotide motif. Since the replication of geminiviruses relies on species-specific Rep interactions and activities, this result could be considered responsible for the competitive interference of BCTIV towards BCTV.