Volcanic ash decreases mating effort in the field cricket Gryllus bimaculatus (Orthoptera: Gryllidae)

Takashi Kuriwada,Gadi V.P. Reddy 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

Volcanic eruptions have serious impacts on ecosystems fromindividual behavior to community structure. Volcanic ash has an especially widespread effect on organisms, as it can be dispersed over a greater distance by the wind than are other volcanic products.We examined the effect of volcanic ash on calling songs and mating behavior of themale field cricket Gryllus bimaculatus De Geer (Orthoptera: Gryllidae). Adult males were randomly assigned to one of four treatments comprising different floormaterial (volcanic ash, filter paper, vermiculite, and Akadama soil), and parameters of calling songs andmating behaviorweremeasured. The dominant frequency of calling song lowered by the volcanic ash. Males reared on volcanic ash and soil exhibited lower calling rates per night. Furthermore, males reared on ash and vermiculite exhibited a longer latency to courtship period than those reared on the other floor materials. Our results showed that floor material does affect the mating efforts of male field crickets.

Volcanic ash decreases dehydration tolerance in the field cricket Gryllus bimaculatus (Orthoptera: Gryllidae)

Takashi Kuriwada,Gadi V.P. Reddy 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.1

Volcanic eruptions have catastrophic impacts on ecosystems, ranging in scale fromeffects on individual behavior to changes in community structure. Volcanic ash has an especially widespread effect, as it can be dispersed over a greater distance than other volcanic products. In this study, weexamined the effect of volcanic ash on the survival and dehydration tolerance of the field cricket Gryllus bimaculatus De Geer (Orthoptera: Gryllidae). Although nymphalmortality, developmental period, and adult body sizewere not affected by volcanic ash, the dehydration tolerance (lifespan without water) of adults reared on a substrate of volcanic ash was lower than that of adults reared on vermiculite. This suggests that volcanic ash may decrease the fitness of field crickets, depending on the availability of water.

Plant cover associated with aboveground net primary productivity (ANPP) mediates insect community composition in steppes of Northwest China

Zi-Hua Zhao,Gadi V.P. Reddy,Shuhua Wei,Mengmeng Zhu,Kaiyang Zhang,Hongqian Yu,Zhanjun Wang,Qi Jiang,Rong Zhang 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Temperate steppe is one of the most important natural habitats for the conservation of arthropod and birdbiodiversity across the Eurasian Tectonic Plate. Since 1950, fragmentation of the steppe habitat has caused a lossof biodiversity and degradation of the species communities found in natural steppe. Therefore, in this study, bothplants and insects were sampled at 56 sites in the steppe biome of northwestern China to explore the effects ofplant community on insect community composition and diversity. The insect community structure varied in thefour different steppe types (meadow steppe, typical steppe, desert steppe, and steppe desert). Plant cover (diversity)was an important driving force, which could enhance number of families and abundance of an insectcommunity. Aboveground net primary productivity and water content of plants had no significant effects oninsect community, although the plant community as a whole did mediate insect composition and communitystructure. Future research should explore the ecological role of particular functional groups in plant and insectcommunities. Supplemental sowing to improve plant diversity in steppe habitat may be another strategy toenhance biodiversity and achieve sustainable management.

Parasitism capacity and searching efficiency of Diaeretiella rapae parasitizing Brevicoryne brassicae on susceptible and resistant canola cultivars

Amene Karami,Yaghoub Fathipour,Ali Asghar Talebi,Gadi V.P. Reddy 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

Different cultivars of aplant species can affect the foraging and efficiency of natural enemies, both directly through physical and biochemical properties or indirectly through the herbivore's diet. In this study, the parasitism capacity and functional response of Diaeretiella rapae McIntosh were determined on the cabbage aphid, Brevicoryne brassicae (L.) reared on susceptible (Opera) and resistant (Okapi) canola cultivars under laboratory conditions at 25 ± 1 °C, 60 ± 5% RH and a16:8 h L:D photoperiod. The parasitoid exhibited Type II and Type III functional responses on the resistant and susceptible cultivars, respectively. The estimated value of searching efficiency (a) was 0.1637 ± 0.1095 h −1 on the resistant cultivar whereas its value was dependent on host density on the susceptible cultivar. The handling times (T h ) on the susceptible and resistant canola cultivars were 0.108 ± 0.040 and 0.320 ± 0.048 h, respectively. The net parasitism rate (C 0 ) of the parasitoid wasp varied from 128.09 hosts per parasitoid lifetime on the susceptible to 71.01hosts on the resistant canola cultivar. The transformation rate from host population to parasitoid offspring (Qp) was equal to 1 on both cultivars (C 0 = R 0 ). The finite parasitism rate (ω) on the susceptible cultivar (0.819 hosts per parasitoid per day) was significantly higher than that on the resistant one (0.578 hosts per parasitoid per day). In conclusion, canola cultivars affected the performance of D. rapae in controlled small-scale laboratory experiments and compared with the susceptible cultivar, the resistant one had anadverseeffect on the efficiency of the parasitoid.

Different pepper cultivars affect performance of second (Myzus persicae) and third (Diaeretiella rapae) trophic levels

Mona Ghorbanian,Yaghoub Fathipour,Ali Asghar Talebi,Gadi V.P. Reddy 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.1

While chemical application can control aphid outbreaks, the overuse of insecticides can make aphids more resistant to these insecticides. These effects make strategies such as host plant resistance combined with biological control agents as an important part of alternative control methods. In this study, the performance of the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) and its parasitoid wasp, Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) were determined on different pepper cultivars (California, Hamedan, Minab, Sabz-Farangi, Sabz-Ghalami, Semnan, Shahroud, and Tehran) in a growth chamber at 25 ± 1 °C, 60 ± 5% RH and a 16:8 h L:D photoperiod. The intrinsic rate of increase (r) of the aphid on the above-mentioned cultivars was 0.3203, 0.3891, 0.3594, 0.3152, 0.3512, 0.3032, 0.3352 and 0.2787 day −1 , respectively. Comparison of the intrinsic rate of increase (r) on different pepper cultivars revealed that Hamedan was the most susceptible and Tehran was the most resistant cultivar. The parasitoids reared on the aphids fed on the susceptible cultivar (Hamedan) had a higher intrinsic rate of increase (0.2641 day −1 ) than those (0.2259 day −1 ) reared on the resistant cultivar (Tehran). These results demonstrated that the quality of host plant affected the performance of M. persicae and its parasitoid D. rapae.

Continuous rearing on Ephestia kuehniella reshaped quality of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

Ghaemmaghami Ehsan,Fathipour Yaghoub,Bagheri Abdoolnabi,Talebi Ali Asghar,Reddy Gadi V.P. 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.2

Continuous mass rearing of Trichogramma brassicae (Bezdenko) at commercial mass-rearing insectaries may affect both quality and performance of natural enemies. In the present study, we studied the quality and per formance of a colony of T. brassicae reared for over 45 generations (G) on Ephestia kuehniella Zeller using two-sex life table parameters and parasitism capacity. Our results revealed that although different generations showed no significant difference in terms of female longevity or total life span until G35, G5 and G10 had the highest values of fecundity, gross reproductive rate (GRR), net reproductive rate (R 0 ), intrinsic rate of natural increase (r), and finite rate of increase (λ). No significant difference in male adult longevity was found among different genera tions. The longest and shortest mean generation times (T) were found in G10 (13.65 ± 2.31 d) and G45 (13.25 ± 3.37 d), respectively. The finite rate of parasitism (ω) ranged from 0.355 ± 2.332 host/parasitoid/day in G5 to 0.242 ± 0.017 host/parasitoid/day in G45. However, ω did not show any significant difference until G20. These results indicate that T. brassicae wasps held under continuous laboratory rearing declined in quality after 20 generations, and therefore periodical rejuvenation of the colony by adding feral parasitoids is strongly recommended.