Journal of Applied Research in Plant Protection
Year:2020 | Volume:8 | Issue:4|Papers Count:5

Extracts of some plants could be used as botanical pesticides because of their lethal effects, repellency and antifeedant activity on insect pests. In this study, bioactivities of different extracts of two plant species, the sickleweed Falcaria vulgaris Bernh and the celery Apium graveolens L., (both belonging to the Apiaceae family) were evaluated against the potato tuber moth (PTM) Phthorimaea operculella (Zeller, 1873). Insects were reared in controlled conditions at 26± 2º C, a photoperiod of 16: 8 (L: D) h and 50± 5% RH, on potato tubers. Foliage of plants were washed by distilled water, and air-dried in shadow. Extraction was carried out by maceration method using hexane, ethyl acetate and methanol as solvents of different polarity, respectively. Ovicidal activity, lethal toxicity against 1st instars and oviposition deterrency of extracts were investigated. The median lethal concentration (LC50) of hexane and ethyl acetate extracts of F. vulgaris against one-day old eggs of PTM was estimated as 2. 5 and 3. 38 g/l, respectively. Also, the same extracts of A. graveolens showed ovicidal activity at concentration rates of 2. 12 and 2. 81 g/l, respectively. Inhalation toxicity of hexane and ethyl acetate extracts of F. vulgaris with LC50 estimated values of 5. 59 and 13. 43 mg/l was significantly more than other extracts. Methanol extracts of both plants showed neither ovicidal nor inhalation toxicity. Ethyl acetate, hexane and methanol extracts of both plants showed effective oviposition deterrency against adults of PTM. Ethyl acetate extract of A. graveolens and F. vulgaris showed 100% and more than 80% oviposition deterrency respectively. Considerable toxicity and oviposition deterrency of both plant extracts detected in this study show their potential as a control agent in PTM management programs.

Yellowing disease of greenhouse and open-grown cucurbits by whitefly-transmitted viruses is dramatically rising in the world and Iran. To study the viral infection of cucurbits in Sistan-Baluchistan Province, 195 leaf samples with viral symptoms were collected and tested for infection of some prevalent cucurbit viruses by RT-PCR using specific primers and some expected amplified DNA fragments were sequenced. Results confirmed the presence of viral infection (%59) in all surveyed areas. Including CABYV, CYSDV, CCYV, CVYV and WmCSV. The most infection of collected samples were %43, % 28 and % 8 of WmCSV, CVYV and CYSDV respectively. Phylogenetic analysis showed that the CYSDV isolates were divided into two sub-groups of East and West and two SB and SB2 isolates with 12 Iranian isolates and 4 Saudi Arabia isolates were clustered in eastern subgroup. Also genetic studies on the part of the coat protein gene showed that in Iranian isolates and Eastern subgroup the CGA had changed to CCA which led to the substitution of Glutamine by arginine at the codon position 73 of coat protein. Therefore, the nucleotide differences of Iranian isolates than the isolates from different regions indicate high genetic diversity and long dating of this native virus in Iran

The cyst nematode is one of the major pathogens of sugar beet, which, many studies has been done for its effective control. The most of existing control methods of cyst nematode are troublesome. Recently, the use of nanoparticles in various aspects of human life, the application of nanotechnology in agriculture and especially in the plant protection has also been considered. However, a detailed study on the effect of zinc and silver nanoparticles on cyst nematode has not been done. In order to examine the possibility of nematode control, the effect of zinc and silver nanoparticles on different life stages of sugar beet cyst nematode (H. schachtii) in vitro and the effect of the nanoparticles on the nematode pathogenicity and damages were assessed under greenhouse conditions. The results of laboratory tests showed increased mortality of larvae, and reduced egg hatching, due to the use of silver and zinc oxide nanoparticles. Mean comparisons of nanoparticles were revealed the more effective of nano silver on the inhibition of the hatching egg and larvae mortality. Results of the effect of nanoparticles on nematode pathogenicity under greenhouse conditions revealed that the nanoparticles reduce the cyst nematode damages. The results showed that silver Nano Silver at a concentration of 100 mg/l mixed with soil were more effective than other treatments. According to the results, probably the toxicity of nanoparticles had been more effective to control of cyst nematode in 100 mg/l nanoparticles in soil mixed method.

Tomato leafminer, Tuta absoluta Meyrick is an invasive quarantine pest that causes high losses on tomato crops in Iran. Predatory bug, Nesidiocoris tenuis Reuter is cosidered recently as potential biological control agent of T. absoluta. In this study, some biological attributes of N. tenuis were stuided on the eggs of T. absoluta at 25± 0. 5˚ C, 65± 5% RH, and 16: 8 h (L: D) photoperiod. A food supply of 10, 20, 30, 40, 50 and 60 prey eggs was provided as high density (above satiation level) for the five nymphal stages and adult N. tenuis, respectively. The prey densities of 5, 10, 15, 20, 25 and 30 eggs were used as intermediate density (satiation level) and 2, 5, 7, 10, 12 and 15 prey eggs as low density (under satiation level) for the same developmental stages and finaly a no prey treatment also was included. The developmental time of immature stages, male longevity and females longevity were 21. 62± 0. 19, 18. 2± 1. 02 and 24. 21± 1. 70d on upper prey density respectively. The average fecundity was 100. 71± 16. 26 nymphs on the same treatment. Net reproduction rate (R0), intrinsic rate of increase (r), and mean generation time (T) were 40. 57± 10. 48 nymphs/generation, 0. 119± 0. 009 d-1and 30. 88± 0. 543 d respectively. The bugs developed no more than 2nd nymphal stage on tomato leaves without prey supply. All life table parameters significantly affected by prey density. These results suggest that N. tenuis can persist in suboptimal condition and continue control of tomato leafminer as long as prey reservoirs are not fully depleted.

In spite of increasing the use of applied research in Trichogrammatidae family, study the morphology of the immature stages of the species seems to be necessary and important. One of the important biological control agents against numerous pests of Lepidoptera is Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae). In the present study, biological traits including the lengths of the developing period of the immature stages, morphological traits were measured in each immature stages of Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) including larvae, prepupae and pupae, as well as mean body length and width and compound eyes spacing by dissecting of parasitized host egg. At 25± 1° C, an average of the larval stage lasted a bit more than two days, the pre-pupa stage was 2. 5 days and the pupa stage was 3. 5-4 days. Neonate Larvae, with an opaque body, which is lack of external morphological characters had the highest mean length ((mean= 0. 98± 0. 002 SEM) and width (mean= 068± 0. 001 SEM) of the body in comparison with other immature stages of development. The emergence of urate disks, promising the being the prepupa stage, appeared approximately 52 hours after egg-laying. Pupa was exarate and without cocoon. As there are very few studies on the immature stages of Trichogramma parasitoid, the results of this study can be used as the basis for other future studies.