Altitudinal adaptation of the life cycle in Allonemobius fasciatus DeGeer (Orthoptera: Gryllidae)

1983 ◽  
Vol 61 (9) ◽  
pp. 1986-1990 ◽  
Author(s):  
Seiji Tanaka ◽  
Victor J. Brookes

Allonemobius fasciatus DeGeer maintains a univoltine life cycle with an embryonic diapause over an altitudinal gradient of as large as 1100 m. Hatching time differs by more than 1.5 months between the highest and lowest altitudes studied. Little or no genetic difference was detected between populations from different altitudes when physiological traits such as diapause intensity, postdiapause development, and nymphal development were compared in the laboratory. Photoperiod influenced the duration of the nymphal stage and the number of instars, compensating for the shorter growing season at higher elevations. This photoperiodic regulation of nymphal development would also serve as a mechanism synchronizing adult emergence within a population of this species.

1973 ◽  
Vol 105 (8) ◽  
pp. 1091-1099 ◽  
Author(s):  
I. D. Hodkinson

AbstractThe four larval instars and the pupa of Ptychoptera lenis lenis Osten Sacken are described. Instars 2 to 4 are very similar morphologically but instar 1 is markedly different. Both a pharate pupal and a pharate adult stage were observed. Larvae are found in stagnant marginal areas of ponds where water depth does not exceed 4 cm and where benthic deposits of plant detritus exceed 8 cm. Fourth instar larvae, under experimental conditions, survived up to 45 days without contact with atmospheric oxygen but development was arrested. P. lenis has a 1 year life cycle with an extended adult emergence season from late May to the end of July.


Author(s):  
Alec R. Lackmann ◽  
Malcolm G. Butler

Except for one unconfirmed case, chironomid larvae have been reported to pass through four larval instars between egg and pupal stages. We have observed a fifth larval instar to be a standard life-cycle feature of the podonomine Trichotanypus alaskensis Brundin 1966 in tundra ponds on the Arctic Coastal Plain near Barrow, Alaska. T. alaskensis has a one-year life cycle in these arctic ponds. Adults emerge in June ~2-3 weeks after pond thaw, then mate and oviposit; most newly-hatched larvae reach instar IV by October when pond sediments freeze. Overwintering larvae complete instar IV within a few days of thaw, then molt again to a fifth larval instar. Imaginal discs, normally seen only during instar IV in Chironomidae, develop across both instars IV & V prior to pupation and adult emergence. While monitoring larval development post-thaw in 2014, we noticed freshly-molted T. alaskensis larval exuviae a week or more prior to any pupation by that species. In 2015-16 we reared overwintering instar IV larvae from single pond sources, individually with daily monitoring, through molts to instar V, pupa, and adult. Some overwintering instar II and III larvae were reared as well, but were few in number. During 2016 we also reared T. alaskensis progeny (from eggs) through instar II, thus documenting head capsule size ranges for all five instars in a single pond’s population. Without individual rearings, the fifth larval instar was not readily apparent for two reasons: 1) The molt itself occurs immediately after thaw and is so synchronous it is difficult to discern in daily field samples. 2) The head capsule size increment between instars IV-V is much lower than the ratio predicted by the Brooks-Dyar Rule. Up through instar IV, the Brooks-Dyar ratio for T. alaskensis ranged 1.30-1.61, but during the IV-V molt head capsule dimensions (sexes pooled) increased by a ratio of 1.09 – comparable to the magnitude of sexual dimorphism in head capsule size within each of the final two larval instars. Individual rearings coupled with 2014-2016 field surveys in nine other ponds suggest that five larval instars is an obligatory trait of this species at this location. As this is the first confirmed case of five larval instars in a chironomid, the phylogenetic uniqueness of this trait needs further investigation.


2012 ◽  
Vol 44 (3) ◽  
pp. 12 ◽  
Author(s):  
Marah Ahmad Dardar ◽  
Hamzeh Mouhammad Ramadan Belal ◽  
Abedlnabi Mouhammad Basheer

<em>Cicadatra persica</em> Kirkaldy, 1909 (Hemiptera: Cicadidae) is regarded as a potential constraint to the productivity of apple fruit orchards in Erneh (33&deg;21&rsquo;N, 35&deg;52&rsquo;E), near Damascus, Syria. However, no research has been conducted on this pest. This study examined adult emergence, egg laying, and hatching periods. Adults emerged in early June, with an emergence peak in the fourth week of June 2011, and started laying eggs in mid-June. Egg development was approximately 40 days, with the first eggs hatching on 1<sup>st</sup> August 2011 and the final hatch on 17<sup>th</sup> August 2011. The simple and relatively successful method of monitoring egg development reported here may be useful for studying the nymphal ecology and life cycle of this species.


2011 ◽  
Vol 8 (11) ◽  
pp. 3159-3168 ◽  
Author(s):  
Y. Xia ◽  
X. Yan

Abstract. Nitrogen (N) fertilizer plays an important role in agricultural systems in terms of food yield. However, N application rates (NARs) are often overestimated over the rice (Oryza sativa L.) growing season in the Taihu Lake region of China. This is largely because negative externalities are not entirely included when evaluating economically-optimal nitrogen rate (EONR), such as only individual N losses are taken into account, or the inventory flows of reactive N have been limited solely to the farming process when evaluating environmental and economic effects of N fertilizer. This study integrates important material and energy flows resulting from N use into a rice agricultural inventory that constitutes the hub of the life-cycle assessment (LCA) method. An economic evaluation is used to determine an environmental and economic NAR for the Taihu Lake region. The analysis reveals that production and exploitation processes consume the largest proportion of resources, accounting for 77.2 % and 22.3 % of total resources, respectively. Regarding environmental impact, global warming creates the highest cost with contributions stemming mostly from fertilizer production and farming processes. Farming process incurs the biggest environmental impact of the three environmental impact categories considered, whereas transportation has a much smaller effect. When taking account of resource consumption and environmental cost, the marginal benefit of 1 kg rice would decrease from 2.4 to only 1.05 yuan. Accordingly, our current EONR has been evaluated at 187 kg N ha−1 for a single rice-growing season. This could enhance profitability, as well as reduce the N losses associated with rice growing.


Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1017
Author(s):  
Sarayut Pittarate ◽  
Julius Rajula ◽  
Afroja Rahman ◽  
Perumal Vivekanandhan ◽  
Malee Thungrabeab ◽  
...  

Fall armyworm Spodoptera frugiperda is a major pest of corn, rice, and sorghum among other crops usually controlled using synthetic or biological insecticides. Currently, the new invention of nanotechnology is taking root in the agricultural industry as an alternative source of pest management that is target-specific, safe, and efficient. This study sought to determine the efficacy of commercial Zinc Oxide (ZnO) nanoparticles (NPs) towards S. frugiperda under laboratory conditions. ZnO NPs were diluted into different concentrations (100–500 ppm), where the baby corn used to feed the S. frugiperda larvae was dipped. The development of the insect feeding on food dipped in ZnO solution was significantly (p < 0.05) affected, and the number of days that the insect took to complete its life cycle had a significant difference compared to the control. There was a significant difference in the adults’ emergence in all the concentrations of ZnO NPs compared to the control, with over 90% of the eggs successfully going through the life cycle until adult emergence. Additionally, several body malformations were observed throughout the lifecycle of the insect. Also, the fecundity of the females was greatly affected. The findings of this study suggest the possibility of exploitation of ZnO nanoparticles not only to manage S. frugiperda but to significantly reduce their population in the ecosystem through body deformations, reduced fecundity, reduced oviposition, and hatchability of eggs. It will be a valuable tool in integrated pest management regimens.


2004 ◽  
Vol 94 (6) ◽  
pp. 569-575 ◽  
Author(s):  
M.A.H. Smith ◽  
I.L. Wise ◽  
R.J. Lamb

AbstractSex ratios of populations of the wheat midge Sitodiplosis mosellana Géhin, developing on wheat Triticum aestivum L., were determined at reproduction, adult emergence, and dispersal. The patterns of sex ratio through the life cycle of S. mosellana result from: (i) a genetic mechanism that causes all or nearly all of the progeny of individual females to be a single sex, with an overall sex ratio that is slightly biased at 54–57% females; (ii) a differential mortality during diapause that increases the sex ratio to 60–65% females; (iii) mating which occurs near the emergence site followed by female dispersal which causes the post-dispersal sex ratio to rise to nearly 100% females; and (iv) oviposition which spreads eggs among different plants and assures that the next generation has a local sex ratio close to the population average. These changes in sex ratio through the life cycle have implications for using crop resistance or pheromones to manage S. mosellana, because mating takes place quickly near emergence sites, and because mated females but not males disperse from emergence sites to oviposition sites. Crop refuges used to protect resistance genes against the evolution of virulence by S. mosellana must be interspersed to prevent assortative mating that would occur in separate blocks of resistant and susceptible plants. Monitoring or mating disruption using a pheromone would be ineffective when wheat is grown in rotation with a non-host crop.


2020 ◽  
Vol 117 (10) ◽  
pp. 5525-5531 ◽  
Author(s):  
Taiki Miki ◽  
Tsugumichi Shinohara ◽  
Silvia Chafino ◽  
Sumihare Noji ◽  
Kenji Tomioka

Insects living in the temperate zone enter a physiological state of arrested or slowed development to overcome an adverse season, such as winter. Developmental arrest, called diapause, occurs at a species-specific developmental stage, and embryonic and pupal diapauses have been extensively studied in mostly holometabolous insects. Some other insects overwinter in the nymphal stage with slow growth for which the mechanism is poorly understood. Here, we show that this nymphal period of slow growth is regulated by temperature and photoperiod through separate pathways in the cricket Modicogryllus siamensis. The former regulates the growth rate, at least in part, through the insulin / target of rapamycin (TOR) signaling pathway. Lower temperature down-regulates the expression of insulin-like peptide (Ms’Ilp) and Target of rapamycin (Ms’Tor) genes to slow down the growth rate without affecting the number of molts. The latter regulates the number of molts independent of temperature. Short days increase the number of molts through activation of the juvenile hormone (JH) pathway and down-regulation of myoglianin (Ms’myo), a member of the TGFβ family, which induces adult metamorphosis. In contrast, long days regulate Ms’myo expression to increase during the fifth to sixth instar to initiate adult metamorphosis. When Ms’myo expression is suppressed, juvenile hormone O-methyl transferase (Ms’jhamt) was up-regulated and increased molts to prolong the nymphal period even under long-day conditions. The present findings suggested that the photoperiod regulated Ms’myo, and the JH signaling pathway and the temperature-controlled insulin/TOR pathway cooperated to regulate nymphal development for overwintering to achieve seasonal adaptation of the life cycle in M. siamensis.


1970 ◽  
Vol 42 (2) ◽  
pp. 157-162 ◽  
Author(s):  
MM Rahman ◽  
W Islam

Acetonic extracts of Akanda was tested against different parameters of the life cycle of Cryptolestes pusillus. The lowest and highest oviposition rate (0.89±0.26 and 2.67±0.33 egg/female/day), hatching rate (14.67±0.53 % and 51.11±0.59 %), adult emergence (16.89 % and 40.89 %), and longevity (male 64.78±1.01day and 105.67±1.09 day) and female (69.56 ± 0.38 day and 113.22±0.57 day) were found in doses (552.413 and 163.678?gcm-2) whereas in control they were 4.89±0.35 egg/female/day, 91.22±1.02 %, 88.44 %, 156.11±1.37 day and 169.67±2.52 day respectively. But highest and lowest incubation period (7.33±0.33 day and 4.89±0.35 day) and developmental period (71.67±0.60 and 39.89±0.26 days) occurred in the same doses and in control these are 4.11±0.26 egg/female/day and 33.44±0.50days. Bangladesh J. Sci. Ind. Res. 42(2), 157-162, 2007


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