Generation-Dependent Functional and Numerical Responses of a Naturally Fungus-Infected Colony of Habrobracon hebetor (Hymenoptera: Braconidae) Reared on Ephestia kuehniella (Lepidoptera: Pyralidae) in Iran

Author(s):  
Fatima Badran ◽  
Yaghoub Fathipour ◽  
Abdoolnabi Bagheri ◽  
Mohammadreza Attaran ◽  
Gadi V P Reddy

Abstract The functional and numerical responses of Habrobracon hebetor (Say) were assessed over 30 sequential generations (G) on different densities (2, 4, 8, 16, 32, 64, and 128 fifth-instar larvae) of the Mediterranean flour moth, Ephestia kuehniella (Zeller). Seven tested generations (G2inf, G4inf, G6inf, G8inf, G10inf, G15inf, and G30inf) had already been naturally infected by a fungus species, whereas only the second generation (G2) had the colonies of both infected (G2inf) and uninfected (G2uninf) individuals. All infected generations, as well as the uninfected generation, showed a Type III functional response. A high variation was found in the handling times (Th) of the parasitoid through 30 sequential generations, and G10inf had the longest handling time. The shortest handling time and the maximum estimated attack rate (T/Th) were observed in G2inf. No significant difference in terms of the number of parasitized hosts was found among all infected generations, as well as between G2inf and G2uninf. Although the handling times in G2inf and G2uninf were close to each other, the attack coefficient of G2uninf was more than that of G2inf. The attack coefficient and handling time of infected generations increased from G2inf to G10inf and then decreased in the higher generations. The most plausible parameters of functional response of infected generations were observed in Ginf. A negative relationship between eggs laid and host densities was observed in the infected generations (G2inf, G4inf, G6inf, G8inf, and G10inf). G2uninf and, among infected generations, Ginf were the best generations for practical utilization in inundative release programs.

2021 ◽  
Author(s):  
Gabriel Monteiro ◽  
Sofía Jorge ◽  
Amanda Fernandes Lemes ◽  
Nathália dos Santos ◽  
Dagmara Ramalho ◽  
...  

Abstract Several biological control programs use Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). The parasitism capacity and the functional response of T. pretiosum parasitizing eggs of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) were studied. To determine the parasitism capacity, females of the parasitoid were individualized, being offered to each female eggs from the host. Daily observations determined the number of parasitized eggs per female, accumulated percentage of parasitism, female longevity and percentage of parasitoid emergence. To establish the functional response, T. pretiosum females were individualized and offered C. cephalonica eggs. Number of parasitized eggs and percentage of adults’ emergence were evaluated, being calculated handling time (Th) and attack rate (a). On the first day of the parasitoid’s life there was parasitism in more than 80% of the host eggs, similar to the percentage of adult emergence throughout the life cycle, and the daily percentage of parasitism. The percentages of eggs of C. cephalonica parasitized were statistically different, with the quadratic model better describing the parasitoid-host relationship, with a positive value of 0.00594, since with the increase in the availability of eggs of C. cephalonica, parasitism was increased. The attack rate was approximately 0.00158, while the handling time of the host eggs was 0.6884 h.


Author(s):  
Azadeh Farazmand ◽  
Masood Amir-Maafi

Abstract In this research, functional responses of Amblyseius swirskii Athias-Henriot preying on different Tetranychus urticae Koch nymphal densities (2, 4, 8, 16, 32, 64, and 128) were studied at eight constant temperatures (15, 20, 25, 27.5, 30, 32.5, 35 and 37.5°C) in a circular Petri dish (3-cm diameter × 1-cm height) under lab conditions. At all temperatures, the logistic regression showed a type II functional response. A nonlinear relationship was found between temperature and attack rate and the reciprocal of handling time. The reciprocal of handling time decreased exponentially with increasing temperature. In contrast, the attack rate grew rapidly with increasing temperatures up to an optimum, showing a decreasing trend at higher temperatures. In order to quantify the functional response of A. swirskii over a broad range of temperatures and to gain a better estimation of attack rate and handling time, a temperature-settled functional response equation was suited to our data. Our model showed that the number of prey consumed increased with rising prey density. Also, the predation rates increased with increasing temperatures but decreased at extremely high temperatures. Based on our model, the predation rate begins at the lower temperature threshold (11.73°C) and reaches its peak at upper temperature threshold (29.43°C). The coefficient of determination (R2) of the random predator model was 0.99 for all temperatures. The capability of A. swirskii to search and consume T. urticae over a wide range of temperatures makes it a good agent for natural control of T. urticae in greenhouses.


2012 ◽  
Vol 9 (2) ◽  
pp. 220-228
Author(s):  
Baghdad Science Journal

This study evaluated the functional response of the larva of the predator Chrysoperla carnea by offering varying densities of cabbage aphid, Brevicoryne brassicae (L.) . Results showed conformity with type–II functional response, where the number of prey killed approaches asymptote hyperbolically as prey density increases (declining proportion of prey killed or the inverse density dependent) till it reached the stability stage determined by handling time and predator satiation. Also, the values of attack rate and handling time changed with age progress for both predator and prey. It has been observed an increase in the attack rate and reduction in handling time with the progress of the predator age when feeding on a particular nymphal instar. The attack rates of the predator was 1.779,3.406 and 4.219 ,while handling time was 0.015,0.010 and 0.008 (days) for 1st,2nd,3rd larval instars respectively, when fed on 1st nymphal instar. Also attack rates decreased and increases handling time with the progress in the prey. The attack rates were 1.779, 1.392, 1.096 and 1.059, due to an increase in size of the predator and in the growing efficiency in hunting the prey as well as in the increase in size of the prey and in developing its ability to defend itself and escape.


Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1511
Author(s):  
Abdelkader Meni Mahzoum ◽  
María Villa ◽  
Jacinto Benhadi-Marín ◽  
José Alberto Pereira

Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is a voracious predator of soft-bodied insects such as juveniles of scale insects and the black scale Saissetia oleae (Olivier) (Hemiptera: Coccidae) is an important pest of several crops, such as the olive tree. However, the predatory efficiency of C. carnea on S. oleae has been unstudied yet. The present work aimed to study the functional response of larvae of C. carnea fed on S. oleae nymphs. In a controlled laboratory environment, increasing densities of S. oleae second and third nymph stages were offered to newly emerged specimens of the three larvae instars of C. carnea. After 24 h, the number of killed S. oleae was recorded and the functional response of C. carnea was assessed. The three larval stages of C. carnea displayed a type-II functional response, i.e., killed prey increased with higher S. oleae densities up to a maximum limited by the handling time. The attack rate did not significantly differ among the three instars while the maximum attack rate was significantly higher for the third instar. The handling time of the first larval instar of C. carnea was higher than that of the third instar. Our results demonstrated that S. oleae could act as a food resource for all larval stages of C. carnea. Furthermore, the third larval stage of the predator was the most efficient in reducing S. oleae densities. These results suggest that C. carnea larvae could contribute to S. oleae control in sustainable agriculture.


2014 ◽  
Vol 50 (No. 3) ◽  
pp. 145-150 ◽  
Author(s):  
F. Sohrabi ◽  
P. Shishehbor ◽  
M. Saber ◽  
M.S. Mosaddegh

Eretmocerus mundus Mercet is one of the key natural enemies of Bemisia tabaci (Gennadius). In this study, the sublethal effects of LC<sub>25</sub> of imidacloprid and field-recommended concentration of buprofezin on the functional response of E. mundus to different densities of second instar B. tabaci nymphs were evaluated. The results revealed a type III functional response in the control and imidacloprid treatment. The type III functional response was altered into a type II by buprofezin. Although imidacloprid did not alter the type of functional response of E. mundus compared to the control, it negatively affected the handling time and maximum attack rate of the parasitoid. Therefore, the use of this insecticide should be evaluated carefully in IPM programs.


Acarologia ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 30-39
Author(s):  
Fereshteh Bazgir ◽  
Jahanshir Shakarami ◽  
Shahriar Jafari

Eotetranychus frosti and Cenopalpus irani Dosse are pests of apple trees that are widely distributed in apple orchards in Iran. The functional responses and predation rates of Amblyseius swirskii, one of the most commonly utilized phytoseiid mites for biological control, on these two pests were evaluated at 25 ± 1 °C, with 16:8 h L: D, and a relative humidity of 60 ± 10 % on apple leaves. The results of predation rate experiments on the two prey species indicated that the predator consumed significantly more eggs than larvae and protonymphs whereas consumption of deutonymphs were very rare. Likewise, the results of logistic regression analysis showed that A. swirskii exhibited a Type II functional response on all immature stages of E. frosti and C. irani. Handling time (Th) increased as prey size enlarged; the lowest handling times were determined as 0.4858 and 0.3819 h on eggs of E. frosti and C. irani, respectively, whereas the highest were found to be 1.4007 and 1.0190 h on deutonymphs, respectively. Amblyseius swirskii had the higher attack rate coefficient (α) on immature stages of C. irani than E. frosti. Attack rate coefficients (α) varied significantly between life stages of both pests with the highest attack rate obtained on eggs, followed by larvae, protonymphs, and deutonymphs. Results of this study suggest that A. swirskii could be a highly efficient biological control agent of E. frosti and C. irani at least at low prey densities.


2017 ◽  
Vol 22 (9) ◽  
pp. 1476 ◽  
Author(s):  
Kajal Patel ◽  
Zhi-Qiang Zhang

The tomato/potato psyllid (TPP), Bactericera cockerelli, is a serious pest of some agricultural and ornamental plants, especially of the Solanaceae family. It has been an invasive species in New Zealand since 2006, heavily impacting the potato and tomato industry. The functional and numerical responses of the phytoseiid predators Amblydromalus limonicus and Neoseiulus cucumeris were examined by offering a range of prey densities (two, four, eight, 12, 16, 20, 24 and 28 TPP eggs or 1st instar nymphs) and compared on a capsicum leaf disc under 25 ± 1ºC, 85% ± 5% RH and a 14:10 h light: dark (L:D) photoperiod. Both species displayed a type 2 functional response when fed on eggs or 1st instar nymphs of TPP, indicating an increase in the number of prey killed with an increase in prey population density. The results were analysed by using a logistic regression and Holling disc equation. A. limonicus had a higher attack rate for both eggs (0.05 ± 0.01) and 1st instar nymphs (0.06 ± 0.01) than N. cucumeris, which had an attack rate of (0.03 ± 0.01) for eggs and (0.02 ± 0.01) for 1st instar nymphs of TPP. N. cucumeris had a longer handling time for both eggs (3.68 ± 0.67 hrs) and 1st instar nymphs (2.50 ± 0.79 hrs) compared with A. limonicus, with a handling time of (1.74 ± 0.23 hrs) for eggs and (1.15 ± 0.15 hrs) for 1st instar nymphs. A. limonicus consistently produced significantly more eggs than N. cucumeris across all densities when fed on either eggs or 1st instar nymphs of TPP. However, the results showed the lack of numerical response of both predator species to prey density. The stronger functional response of A. limonicus to TPP eggs and 1st instar nymphs indicates that this species can potentially be a more effective biocontrol agent of TPP than N. cucumeris.


Sign in / Sign up

Export Citation Format

Share Document