جستجوی مقالات مرتبط با کلیدواژه "khapra beetle" در نشریات گروه "گیاهپزشکی"

Trogoderma granarium (Everts) is an economic insect pest of stored grains in Iran and many tropical and subtropical regions. If stored products contaminated with this insect are consumed by humans, it would cause serious digestive diseases. To control T. granarium in storage, chemical insecticides and fumigants are often used, but due to their extreme toxicity to humans and other dangerous side-effects, their application has been limited. Therefore, in order to develop alternative control methods with minimal harmful effects to humans and other non-target organisms, there is a need to understand feeding performances of the pest on different cultivars. The use of insect-resistant plants is one of the effective methods in integrated pest management programs. Study of nutritional indices of stored product insects is one of the important methods of measuring the resistance in plant cultivars.

Nutritional indices of T. granarium larvae were investigated using the gravimetric method provided by Wadbauer (1968). The grains of wheat genotypes including N-91-9, Heidari, Aftab, Tirgan, N-92-19, Gaskojen and Kouhdasht were crushed using a grinder. Then, first instar larvae were reared on the grains of these genotypes under 33 ± 1°C, 65 ± 5% R.H., and 14:10 (L:D) h. After emergence of fifth instar, the weight of larvae, before and after feeding, and the amount of grain eaten by the larvae were measured. The data were analyzed using one-way ANOVA using SPSS ver.16. Then, Tukey's HSD test, with a probability level of 5%, was used to investigate the statistical differences among the means.

There were significant differences in the nutritional indices of T. granarium fifth instar larvae on grain of different wheat genotypes. The larvae raised on line N-91-9 had the lowest weight of food consumption (24.33 ± 3.38 mg/10 larvae) compared to other genotypes tested. Larvae fed with line N-91-9 (5.33 ± 0.33 mg/10 larvae) and cultivars Aftab (3.00 ± 0.57 mg/10 larvae) and Heidari (3.00 ± 0.57 mg/10 larvae) showed lower weight gain than those fed with other genotypes. The highest efficiency of conversion of ingested food (ECI) was on cultivars Gascojen (36.56 ± 1.46 %) and Tirgan (33.42 ± 0.60 %), and the lowest was observed on cultivars Aftab (7.32 ± 1.51 %) and Heidari (7.86 ± 1.38 %). The highest relative consumption rate (RCR) was found on cultivar Gascojen (1.08 ± 0.05 mg/mg/day) and line N-92-19 (0.95 ± 0.02 mg/mg/day), and the lowest was seen on line N-91-9 (0.16 ± 0.03 mg/mg/day), and cultivars Heidari (0.19 ± 0.02 mg/mg/day) and Aftab (0.24 ± 0.02 mg/mg/day). As compared with the other examined genotypes, the relative growth rate (RGR) was the highest on cultivar Gascojen (0.394 ± 0.022 mg/mg/day). Larvae feeding from cultivar Gascojen (5.61 ± 0.17 mg/day) had the highest growth rate (GR), and larvae feeding from line N-91-9 (0.76 ± 0.04 mg/day) and cultivars Heidari (0.42 ± 0.08 mg/day) and Aftab (0.42 ± 0.08 mg/day) had the lowest GR value. The change in the nutritional indices of T. granarium larvae can be due to the differences in physical and chemical characteristics of the grains of tested wheat genotypes. The ECI index represents the ability of an insect to use eaten food to increase its body size and weight. In other words, the increase in ECI value on cultivars Gaskojen and Tirgan indicates the high ability of fifth instar larvae to convert the eaten grain into body biomass. This finding may be due to the high protein content and low grain hardness of these cultivars. The low weight of food eaten and body weight in larvae fed with cultivar Heidari and line N-91-9 may be due to the high grain hardness of these genotypes.

Our results showed that line N-91-9 and cultivars Heidari and Aftab had lower nutritional value than the other tested genotypes for T. granarium larvae, because the amount of food eaten, larval weight gain and nutritional indices of larvae fed with these genotypes were lower than other genotypes tested. So, these two genotypes can be used in genetic engineering programs to minimize the damage of T. granarium. The presence of defensive chemical compounds, grain hardness or the lack of essential nutrients for the development of the pest may be the reason why some of the tested cultivars are unsuitable for T. granarium feeding.

The khapra beetle, Trogoderma granarium (Everts) is one of the most important insect pests of stored products, especially wheat grains, in Iran and some other countries of the world. In this research, effect of various wheat genotypes including Heidari, Aftab, Gaskojen, Kouhdasht, Tirgan, N-91-9, and N-92-19 was studied on biology and two-sex life table parameters of T. granarium under 33 ± 1°C, relative humidity of 65 ± 5%, and a photoperiod of 14:10 (L:D) h. Our results showed that the immature period of T. granarium was the longest on N-91-9, Heidari, and Aftab. The net reproductive rate (R0) ranged from 9.03 offspring on N-92-19 to 34.13 offspring on Gaskojen. The lowest intrinsic rate of increase (r) was for T. granarium reared on Heidari, Aftab, N-91-9 and N-92-19. The results of this study indicated that Heidari, Aftab, N-92-19 and N-91-9 were unfavorable genotypes for T. granarium development and population increase. These genotypes could be used as one of the sources of resistance in management programs of T. granarium.

Rice (Oryza sativa L.) is one of the most important cereal grains and serves as a staple food for nearly half of the world’s population. Trogoderma granarium Everts (Coleoptera: Dermestidae), commonly known as the Khapra beetle, is a significant pest that infests stored grains and other stored products in various countries worldwide, including Iran. The pest's polyphagous nature and high ability to survive for extended periods without food necessitate using chemical fumigants to control T. granarium in storage facilities. However, the serious adverse effects of these insecticides on humans and the environment render it imperative to explore alternative pest control approaches. One of the best safe options is using resistant cultivars in integrated pest management programs. Insect-plant interactions and the resistance of various cultivars to herbivorous insects can be studied by insects’ life history and population parameters.

The resistance and susceptibility of six commercial rice cultivars (Tisa, Khazar, Shafagh, Sadri, Nemat, and Hashemi) to T. granarium were determined by analyzing the life history and population growth parameters of the pest. The seeds of tested rice cultivars, which have a large cultivation area in Iran, were obtained from the Agricultural and Natural Resources Research Center (Gilan province, Iran). The initial colony of T. granarium was obtained from the laboratory of Department of Plant Protection, University of Mohaghegh Ardabili (Ardabil, Iran), and was reared in groups on wheat seeds (as the main host). The adult insects obtained from the primary colony were transferred to the seeds of tested rice cultivars (20 pairs on each cultivar), and were reared as a group for two generations. Then, the eggs (1-day-old) laid on each rice cultivar were used for the experiments. The beetle rearing and all experiments were carried out in a growth chamber set at 33 ± 1°C, 65 ± 5% RH, and 24 h darkness. Subsequently, the raw data obtained from the life history of T. granarium on various rice cultivars were analyzed with TWOSEX-MSChart software using an age-stage, two-sex life table model.

The study results indicated that immature survival rate on cultivar Sadri was higher than on the other tested cultivars. The incubation period was longer on cultivar Shafagh than on cultivars Sadri and Tisa. The shortest larval, pupal and the entire immature periods were observed on cultivars Sadri and Tisa, and longest on cultivar Khazar. The beetles raised on cultivar Khazar took approximately eight days longer to complete their development than those on cultivar Sadri. The fecundity of T. granarium (number of eggs laid by each female) on cultivars Sadri and Tisa was significantly higher than on cultivar Khazar. The longest oviposition period was observed on cultivars Sadri and Tisa, and the shortest on cultivar Khazar. The longevity of female and male adults was longest on cultivars Sadri and Tisa, and shortest on cultivar Khazar. The intrinsic rate of increase (r) was highest on cultivar Sadri and lowest on cultivars Hashemi, Shafagh, and Khazar. Additionally, the finite rate of increase (λ) was higher on cultivars Sadri and Tisa than on the other tested cultivars. The longest mean time generation was observed on cultivar Khazar and the shortest on cultivars Sadri and Tisa.

One of the reasons for the rapid development and high survival of T. granarium on cultivar Sadri may be the high protein content of its seeds, which has provided sufficient energy for the immature stages' rapid growth. However, the amount of protein and starch in cultivar Khazar is lower than in other cultivars, which may be a factor in this cultivar's resistance to T. granarium. Our results indicate that Sadri and Tisa are the most susceptible cultivars to potential population increase of the pest because the highest values of r and λ are on these two cultivars. However, owing to the highest values of r and λ on cultivars Hashemi, Shafagh, and Khazar, they are the most resistant cultivars to T. granarium. Consequently, resistant cultivars can be used in the genetic engineering of plants to minimize the damage caused by this key pest.

The khapra beetle, Trogoderma granarium (Everts), 1898 is one of the damaging pests of different stored cereal grains in Iran. In this research, effect of four cereal grain species including wheat (varieties N-91-9 and Aftab), barley (varieties Dasht and Oxin), maize (varieties AR and 704), and rice (varieties Hashemi and Fajr) was studied on nutritional indices and digestive proteolytic and amylolytic activities of T. granarium fifth instar at 33±1˚C, relative humidity of 65±5% and a photoperiod of 14: 10 (L: D) h. The results showed that the highest food consumption by larvae was observed on wheat N-91-9 and the lowest value was seen on maize 704 and rice Fajr. The relative growth rate was the highest on wheat N-91-9 and barley Dasht. The highest proteolytic activity was in larvae fed on wheat Aftab, barley Dasht and rice Hashemi, and the lowest activity was in those fed on rice Fajr. The amylolytic activity of larvae fed on varieties Dasht, N-91-9, Hashemi and AR was significantly higher than those fed with other tested cereals. The results of this study indicated that barley Dasht and both wheat varieties tested were relatively more favorable than other examined cereals for feeding of T. granarium larvae.

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is a serious pest of cereal grains such as wheat. In the present research, the lethal and sublethal effects of essential oils (EOs) from Piper nigrum L. and Artemisia khorassanica Podl. were determined against 1st instar larvae of T. granarium. To study the sublethal effects, 1st instar larvae were exposed to the LC30 of each EO, and the life table parameters of the surviving insects were assessed. Artemisia khorassanica (LC50: 39.88 μl/liter air) had higher fumigant toxicity for T. granarium when compared to P. nigrum (LC50: 71.46 μl/liter air). Furthermore, the insecticidal effects of A. khorassanica (LT50: 13.51 h) were faster than P. nigrum (LT50: 15.75 h). Significant differences in the larval and pupal durations were observed in the EO treatments when compared to the control. In addition, the exposure to sublethal concentration of the EOs tested significantly reduced immature survival rate, adult longevity and fecundity. The net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) was significantly affected by EOs tested being lowest in the insects exposed to A. khorassanica. According to our findings, both EOs tested, especially A. khorassanica, are useful for the effective control of T. granarium in warehouses.