جستجوی مقالات مرتبط با کلیدواژه "Aphis fabae" در نشریات گروه "گیاهپزشکی"

The black bean aphid, Aphis fabae </em>Scopoli (Hemiptera: Aphididae), is one of the most important pests of several cultivated crops throughout the world. The predatory bug Deraeocoris lutescens</em> (Schilling) (Hemiptera: Miridae) have privileged position in biological control of aphids such as the black bean aphid, A. fabae</em>. Recently, there has been a growing interest in research concerning the possible use of plant extracts as alternatives to synthetic insecticide. In the present study, the effect integration of natural enemy with commercial pesticides (pirimicarb and abamectin) and plant extracts Melia azedarach</em> and Peganum harmala</em>, to control of A. fabae</em> were investigated. The result showed, combination of plant extracts M. azedarach</em> and P. harmala</em> with natural enemy causes significant decrease in this pest population and M. azedarach</em> has less hazardous on natural enemies. Also, the effects of commercial pesticides and plant extracts on the prey consumption of natural enemies were evaluated. Totally, the results of these experiments indicated that the ethanolic extract of M. azedarach </em>and pirimicarb have a minimum impact on the mortality of natural enemies, and the ethanolic extract of M. azedarach </em>has a minimum impact on the feeding of natural enemies.

The black bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae), is one of the most important pests of several cultivated crops throughout the world. The predatory bug Deraeocoris lutescens (Schilling) (Hemiptera: Miridae) have privileged position in biological control of aphids such as the black bean aphid, A. fabae. The other method to control aphids is the usage of insecticides and plant-derived chemicals. Integrated Pest Management (IPM) is an ecosystem approach to crop production and protection that combines different management strategies and practices to grow healthy crops while minimizing the use of pesticides. Recently, there has been a growing interest in research concerning the possible use of plant extracts as alternatives to synthetic insecticide. In this study, the integration of D. lutescens (N1 and N5 instar) with plant extracts of Peganum harmala L. and Melia azedarach L. and two conventional insecticides (pirimicarb and abamectin) is surveyed to manage A. fabae (1-2 and 5-6 days old), and also study the impacts on the predatory bug. Among different treatments, integration of N5 instar of the predatory bug with P. harmala has the highest aphid (1-2 days old) mortality rate (%95.33±0.60), and integration of N5 instar as the natural enemy with pirimicarb has the highest effect to manage 5-6 days old aphids (%94.00±0.71).

 Demographic toxicology is usually the best way to evaluate total effects of pesticides on a population of natural enemy. Lethal and sublethal effects of imidacloprid, pymetrozine and Dayabon® were investigated on the sexual population of Lysiphlebus fabarum at laboratory conditions. Toxicity of the insecticides on immature stages of L. fabarum was evaluated, by dipping leaves containing parasitized Aphis fabae. These insecticides significantly reduced adult emergence rate when parasitized aphids were treated with field-recommended concentrations at larval stage. Imidacloprid had more toxicity than pymetrozine and Dayabon® at pupal stage. Imidacloprid was significantly more toxic than pymetrozine at adult stage. Dayabon® did not have residual effect on adults. In order to assess sublethal effects of three insecticides on life-table parameters of L. fabarum, the concentrations that had 25% mortality threshold and field-recommended concentrations were used for larval, adult and pupal stages treatments, respectively. Adults’ longevity, mean fecundity, females' oviposition period, sex ratio and some population parameters (r,λ, R0) were negatively affected by application of imidacloprid in comparison with other insecticides and control at larval, pupal and adult stages treatments. The intrinsic rate of increase (r) values for imidacloprid treatment and control at larval, pupal and adult stages of parasitoid were 0.2035 ± 0.01, 0.2240 ± 0.01 and 0.2273 ± 0.01 (day-1) and 0.2635 ± 0.01, 0.2759 ± 0.01 and 0.2687 ± 0.01 (day-1), respectively. According to obtained results, pymetrozine and Dayabon® could be used to control A. fabae in combination with L. fabarum.

 The cotton aphid, Aphis gossypii, is an important pest on greenhouse crops such as the cucumber. Natural enemies have often been used successfully to control greenhouse pests. Among different pests, aphids because of their high reproductive rate are particularly difficult to control biologically.  In this study, the effects of separate and simultaneous application of the parasitoid wasp Lysiphlebus fabarum and the predator ladybird beetle Hippodamia variegata were studied to control A. gossypii on cucumber as an integrated pest management program. The replicates (n= 10) in all treatments included 10 cucumber plants in separate pots and were infected with five winged A. gossypii placed in a cage with a banker plant system of Vicia fabae-Aphis fabae. With the introduction of mummified aphids on a bean shoot (every two days), a pair of male and female adult ladybird beetles (every three days) or simultaneous application of both biocontrol agents, the numbers of aphids were counted in the three treatments. The results revealed that the parasitoid wasp L. fabarum alone was unable to control A. gossypii, but H. variegata performed better. The best performance was observed for simultaneous application of both biocontrol agents. Moreover, in the combined agents’ treatment, the number of A. gossypii on the both lower and upper cucumber leaves was not significantly different compare to other treatments that biological agentswere used seperatly. The number of mummified aphids did not differ between treatments at the end of the experiments. This is indicative of the tendency for ladybird beetles to feed on different growth stages of non-parasitized aphids compare to parasitized aphids containing immature stages of L. fabarum. The results indicate thatthe simultaneous application of both biocontrol agents is effective for the control of A. gossypii, although more research under greenhouse condition is needed.

In superparasitism, a host is parasitized by one or more conspecific females, a phenomenon resulting in immature competition within the host’s body. In the present study, the competition between sexual and asexual strains of the parasitoid wasp, Lysiphlebus fabarum (Marshall) (Braconidae: Aphidiinae), was studied in simultaneous and successive introductions. The biological traits by both strains were determined in surviving individuals of superparasitized aphids as well. For this purpose, eight wasp females of each strain were introduced into 40 second instar of black bean aphid, Aphis fabae Scopoli, simultaneously or by a 24-hour priority. Our results revealed that the early introduction of each strain had a significant effect on the number of emerging adults of that strain. However, in simultaneous introduction, a greater number of sexual progeny emerged than asexual ones. The development time of sexual progeny was significantly decreased when their females were introduced earlier into the host aphids. Other morphological and biological traits (hind tibia length, head width, ovary area, egg load and egg size) of surviving individuals of superparasitized aphids were not affected by the oviposition sequence of the strains. The findings showed that sexual L. fabarum females were successful in competition with asexual females, the superiority of which could be more important in a host limitation conditions.

The common pistachio psylla (CPP), Agonoscena pistaciae Burckhardt and Lauterer, 1989 (Hem.: Psylloidea: Rhinocolinae) is an important pest of pistachio trees. The presence of a large population of psyllid causes severe problems such as falling buds and leaves and therefore this pest causes heavy economic damage to farmers. Predators are the largest and the most diverse natural enemies of the CPP. They are offered as biological control agents against pistachio pests, especially CPP, although they are mostly general predators. Oenopia conglobata contaminata (Menteries) is one of the common psylla predators of pistachio orchard that have a significant role in biological control of Agonoscena pistaciae population. Despite the importance of this efficient predator, the limited study has been done on the effect of different hosts on the biological parameters of this lady beetle. In this study, the demographic parameters of this lady beetle by feeding on 4 different prey species, A. pistaciae , Aphis fabae Scopoli (Hem.:Aphididae), Aphis gossypii Glover (Hem.:Aphididae) and eggs of Ephestia kuehniella (Zell.)(Lep.:Pyralidae) were studied in the laboratory conditions (25 ± 2°C, relative humidity of %65 ±5 and photoperiod of 16 hours light and 8 hours of darkness).
Nymphs of CPP (A.pistaciae) and adults of O. conglobata contaminata beetles were collected on the pistachio leaves from a pistachio orchard. Aphids (A. fabae and A. gossypii) were reared on the bean and the cotton plants planted in a greenhouse. Eggs of E. kuehniella were prepared from insectarium of Kerman Plant protection management and rearing of E. kuehniella was done in the laboratory conditions in Kerman Agricultural and Natural Resoarce Research Center. Before starting the experiment, one generation of O. conglobata contaminata was reared in the laboratory on the different host separately. One hundred eggs of O. conglobata contaminata were used to determine the demographic parameters. After hatching of eggs, larvae was individually transferred to a plastic container (5*10 cm) and kept in a growth chamber. Every day the larvae were fed with the above mentioned host. Their growth and development were monitored daily and also mortality rate was recorded. In the experiments, fourth-instar nymph of the aphids and A. pistaciae were used. The raw data of the developmental time and female daily fecundity of O. conglobata contaminata individuals were analyzed based on the age-stage, two-sex life table using the computer program TWO SEX MS Chart.
Results showed that the maximum net reproduction rate (R0) and intrinsic rate of increase (rm) in psylla diet was 290.87 , 0.1559, respectively and the minimum of R0 and rm belong to eggs of E. kuehniella diet (61.68 and 0.1103). This result proves that psylla diet is the best food for O. conglobata contaminata and aphids diets were in the next ranks (R0 and rm in A.fabae and A.gossypii diets were 200.48, 0.140; 72.44,0.128, respectively). Results of mean generation time of O. conglobata contaminata that was rearing on different diets showed that there were significant differences among the different diets. Mean generation time of O. conglobata in Psylla, A.fabae, A.gossypii and egg of E. kuehniella diets were 36.31, 37.72, 33.34 and 37.30 days, respectively. Finite rate of increase (λ) of O. conglobata contaminata by feeding A.pistasciae, A.fabae, A.gossypii and E. kuehniella was determined 1.198, 1.150, 1.136 and 1.116, respectively.The results of this study can be compared with the result of Mokhtari and Samih (2014), Rounagh and Samih (2014) and Hassani et al. (2009). Life expectancy of female and male O. conglobata contaminata by feeding A.pistasciae, A.fabae, A.gossypii and E. kuehniella were 80.82,64.16; 81.02,68.76; 80.54,68.88 and 59.75, 62.11 days, respectively. Results also indicated that the psylla and A.fabae diets improved the demographics parameters and the life expectancy of O. conglobata contaminata.
The results illustrated that this predator by feeding on nymphs of A. pistaciae has the highest intrinsic rate of increase (rm) and with respect to the demographic parameters, it was the most suitable prey .The compare of O. conglobata contaminata -rm that rearing by CPP with A. pistaciae -rm proves that this predator can control of A. pistaciae in the field and this ladybeetle can be used in IPM of pistachio orchards. According to the difficulty of rearing CPP in laboratory conditions, aphids are suitable preys for mass rearing of O. conglobata contaminata in insectariums.

Intraguild predation is defined as killing and eating another predator species as potential competitors that depends upon the same or limited resources. In this study, intraguild predation between the ladybird Hippodamia variegata Goeze and the parasitoid wasp Lysiphlebus fabarum (Marshall) was investigated in association with cotton aphid, Aphis gossypii, on cucumber plants. Host preference for healthy or previously parasitized aphids in third instar larvae and adult females of H. variegata was studied in a choice access situation as well as in a Y-tube olfactometer bioassay. We cut an antenna of each experimental aphid to reliably distinguish the parasitized aphids from healthy ones. All experiments were performed at 22±1°C, 60%–70% RH, and a 16:8 (L:D) photoperiod. Based on the pre-test results, cutting the antenna of aphids, did not significantly affect the host preference of adults or third instar larvae of ladybirds. In a choice access test, female ladybirds significantly preferred healthy aphids to previously parasitized ones (24 and 72 hours: t =2.15, df =1,18, P =0.04 and t =6.35, df =1,18, P

Mass production of natural enemies has been considered a necessity for biological control programs. Most beneficial insects have a relatively short shelf-life, so suppliers do not have a sufficient number of biocontrol agents. The development of storage techniques for biocontrol agents provides flexibility and efficiency in mass production. Cold storage by prolonging insect development times provides a steady and sufficient supply of insects and synchronizes a desired developmental stage of biocontrol agents with times of pest outbreaks; so it reduces the cost of biocontrol programs by enlarging the production period over several months. Cold storage is usually associated with major fitness costs. Even if the insects remain alive after cold storage, a reduction of fitness may be observed, so the production of high quality natural enemies must be ensured. Developing effective methods is necessary in mass-producing. It has been reported that using fluctuating thermal regimes (FTR) (i.e. cold exposure interrupted by periodic short pulses of high temperature) versus constant thermal regimes (CTR) can progress the quality of biological control agents and significantly reduce rates of mortality. In this study, the impact of fluctuating thermal regimes versus constant low temperatures on the emergence rate, sex ratio, post-storage development time, adult size, egg load and egg size of the parasitoid wasp, Lysiphlebus fabarum (Marshall) was studied. The test was examined in three cold storage periods (1, 2, or 3 weeks). Lysiphlebus fabarum is an aphidiine parasitoid which attacks more than 70 species of aphids. Although both sexual (arrhenotokous) and asexual (thelytokous) populations of L. fabarum have been reported in Iran, the former population has been studied in this research. A stock colony of black bean aphid, Aphis fabae Scopoli (Hemi., Aphididae) was established from material collected in bean fields in Khuzestan province, Iran, in spring 2012. A sexual population of the parasitoid wasp, L. fabarum was collected from black bean aphids feeding on broad bean, Vicia fabae L. The synchronous cohort of L. fabarum was produced on the 2nd instar of aphid (at 21±1 ºC, 50–60% r.h., and L14:D10 photoperiod), then 30 two-day-old mated females were introduced into aphid colony consisting of 200 2nd instar individuals. The females were removed after 10 hours and parasitized aphids were reared for 54 hours (±6) to complete development to the late-instar larvae. These parasitized aphids, which were harboring late-instar larvae of wasp, were subjected to 6 ºC (as constant temperature regime) or were stored at 6 ºC with 2 hours daily exposure to 21±1 ºC (as the fluctuating temperature regime). The experiment was replicated with three cold storage periods (1, 2, or 3 weeks) with a control (direct development at 21±1 ºC). After completion of each storage temperature treatment, insects were transferred back to 21 °C until the emergence of adult wasps. Accordingly, the survival rate and the sex ratio (% females) were determined. The emerged wasps were then exposed to alcohol vapor for 2 minutes. The hind tibia of both gender was measured. Subsequently, the ovaries of each female were dissected to determine the egg load and egg size. According to results in CTR, survival of larvae was significantly reduced after one week of storage, and there was a gradual decrease in the second week, but there was no difference between survival of wasps that were stored after one and two weeks of storage. In FTR, emergence rate was decreased after one and two weeks of storage in comparison to the control, and the least survival was observed in the third week. When the survival was compared between different thermal regimes, FTR increased the survival in the first and second weeks, whereas after three weeks of storage there was no significant difference between two thermal regimes. In CTR, the least sex ratio of wasps was observed in those stored for two weeks, although there was no significant variation in sex ratios for control, one week and three week of storage. In FTR, cold storage did not affect on sex ratios of treatments. When the sex ratio was compared between different thermal regimes, for two and three weeks of storage, it was significantly higher in FTR and CTR, respectively. In females and males, larval storage increased development time relative to controls, in CTR. While in FTR, developmental time was decreased after two and three weeks of storage, in FTR. When developmental time was compared between two thermal regimes, post-storage development was slower in CTR after two and three weeks of storage in comparison to FTR, in both genders. In both thermal regimes, cold storage of wasps as larvae resulted in smaller male and female wasps relative to controls over all the storage periods. Egg load and egg size at emergence were progressively diminished as a function of the storage period, regardless of the thermal regimes. Egg load of wasps stored in CTR compared with FTR, was significantly higher for three weeks of storage. For all storage periods, egg size was significantly higher in FTR than CTR. Collectively, our results confirmed the beneficial effect of FTR relative to CTR, when larvae of L. fabarum were stored for two weeks at 6 °C. Although FTR reduced the development time, which could be a problem during delivery for mass release of natural enemies in the field, but the emergence rate, the sex ratio, the body size and the egg size were significantly higher in FTR than those in CTR. For three weeks of storage, FTR was more stressful than the CTR, as the wasps that were stored in CTR had significantly more post-storage development, sex ratio, body size and egg load than the fluctuating ones.

Oenopia conglobata is an important active predator of pistachio psyllid in pistachio orchards. Alternative host or prey has an important role in the stability of natural enemies population in nature. In this study, prey preference of 4th larval instar, male and female of O. conglobata were examined in 10 replications. Nymphs and adults of Agonoscena pistaciae, Aphis fabae, Aphis gossypii and eggs of Ephestia kuehniella with corn pollen were used as preys. In order to study the effects of these preys on consumption rate of adult stage of O. conglobata when feeding only on the common pistachio psylla, it was reared on each diet separately and the feeding percentage was determined after 24 hours. The results showed that the larvae and adults of this predator prefer nymphs of pistachio psylla to other preys. They fed 87±1.52 and 85.5± 1.74 % of psyllid nymphs, respectively. The Manly preference index in the prey-preference test on different diets also showed more preference to nymphs of pistachio psylla compared to other diets. Those predators reared on psylla had more consumption rate on pistachio psylla nymphs (99.2±0.512 %) than to other preys. The results showed that O. conglobata preferred common pistachio psylla to other preys and the common pistachio psylla is a suitable prey for rearing of this predator, but due to feasibility and rearing expenses, A. fabae as a second prey is the most favourable prey for rearing of O. conglobata for biological control of A. pistaciae.

Lack of quality control methods during the mass rearing of natural enemies may lead to failures in biological control. Body size has important effects on fitness components of parasitoids، and often use as a standard measure of quality control. In the present study، the most appreciate morphological feature that provides the best correlation with body size and egg load in a sexual population of the parasitoid wasp، Lysiphlebus fabarum (Marshall) was determined، when females reared on different nymphal instars of the host aphid، Aphis fabae Scopoli. The experiments were performed under standardized conditions in a growth chamber (21 ± 1°C، 60–70% RH، and 16L: 8D)، and candidate metrics were head width، length of the right forewing، and length of the right hind tibia. According to results، head width emerged as the most suitable proxy for total body length of females that were reared in the 2nd nymphal instar (the most suitable host growth stage for mass rearing)، while length of the right forewing yielded the highest correlation with total body length، when the data of wasps reared in all four nymphal instars were pooled. Egg load increased linearly with body length across all host growth stages، and the forewing length had the highest correlation with females reared in all four nymphal instars، so it may serve as a better predictor of egg load than other measurements. The results suggest that forewing length can be used as a proxy of quality control in mass rearing of this population of L. fabarum.

In this research، the effect of host instars was evaluated on time allocation to various foraging behaviors in sexual population of the parasitoid wasp، Lysiphlebus fabarum (Marshall) (Hym.، Braconidae: Aphidiinae). For this purpose، the parasitoid wasps reared in the second instar of black been aphid، Aphis fabae Scopoli (Hem.، Aphididae) were introduced separately to leaf patches that included 15 of the second or fourth instar of the aphid. Next، foraging behaviors of wasp females and host defensive behaviors of aphids were recorded for 30 minutes. According to the results، the host instars did not affect time allocation to various foraging behaviors within a patch. The results also showed that the number of defensive behaviors of two host instars، including kicking and producing droplets of cornicle secretions was significantly different when exposed to parasitoid wasps. The second and fourth instar aphids displayed significantly more kicking and cornicle secretions behaviors، respectively. Frequency of attack orientations relative to the aphid body (anterior، posterior، and lateral) was also tallied. The most attacks on second instar were launched from a lateral orientation، which may present a lower risk of kicking and smearing with cornicle secretions.