scholarly journals The Amino Acid-Mediated TOR Pathway Regulates Reproductive Potential and Population Growth in Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae)

2020 ◽  
Vol 11 ◽  
Author(s):  
Haowen Zhu ◽  
Sui Zheng ◽  
Jinming Xu ◽  
Qing Wu ◽  
Qisheng Song ◽  
...  
Keyword(s):  
Population Growth ◽  
Regulatory Mechanism ◽  
Brown Planthopper ◽  
Reproductive Potential ◽  
Tor Pathway ◽  
Cyrtorhinus Lividipennis ◽  
Mirid Bug ◽  
Predatory Mirid ◽  
Predatory Capacity ◽  
Gramineous Species

The predatory mirid bug, Cyrtorhinus lividipennis Reuter, feeds on brown planthopper (BPH) eggs that are deposited on rice and gramineous plants surrounding rice fields. The development and reproduction of C. lividipennis are inhibited by feeding on BPH eggs from gramineous species, and the underlining regulatory mechanism for this phenomenon is unclear. In the present study, HPLC-MS/MS analysis revealed that the concentrations of six amino acids (AAs:Ala, Arg, Ser, Lys, Thr, and Pro) were significantly higher in rice than in five gramineous species. When C. lividipennis fed on gramineous plants with BPH eggs, expression of several genes in the target of rapamycin (TOR) pathway (Rheb, TOR, and S6K) were significantly lower than that in the insects fed on rice plants with BPH eggs. Treatment of C. lividipennis females with rapamycin, dsRheb, dsTOR, or dsS6K caused a decrease in Rheb, TOR, and S6K expression, and these effects were partially rescued by the juvenile hormone (JH) analog, methoprene. Dietary dsTOR treatment significantly influenced a number of physiological parameters and resulted in impaired predatory capacity, fecundity, and population growth. This study indicates that these six AAs play an important role in the mediated-TOR pathway, which in turn regulates vitellogenin (Vg) synthesis, reproduction, and population growth in C. lividipennis.

Implications of using two natural enemies of Tuta absoluta (Lepidoptera: Gelechiidae) toward tomato yield enhancement

2019 ◽  
Vol 109 (05) ◽  
pp. 617-625
Author(s):  
M.A. Mirhosseini ◽  
Y. Fathipour ◽  
M. Soufbaf ◽  
G.V.P. Reddy
Keyword(s):  
Total Yield ◽  
Egg Parasitoid ◽  
Tuta Absoluta ◽  
Yield Enhancement ◽  
Leaf Miner ◽  
Trichogramma Brassicae ◽  
Tomato Yield ◽  
Nesidiocoris Tenuis ◽  
Mirid Bug ◽  
Predatory Mirid

AbstractTomato leaf miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive tomato pests worldwide. We tested quantity and quality of tomato fruits after simultaneous use of two biological control agents, the predatory mirid bug Nesidiocoris tenuis (Reuter) and the egg parasitoid Trichogramma brassicae Bezdenko against TLM. We varied the timing of predator releases (before or after pest establishment) and the number of parasitoids released (ten or 30 females per week per m2). The highest number of fruits per cage, percentage of undamaged fruits, total yield weight, and undamaged yield weight were all obtained with predator-in-first treatments, with or without parasitoid releases. Furthermore, measures of fruit quality were also highest in predator-in-first treatments, including, highest percentage of water, greatest proportional fresh weight of carbohydrates, most lycopene, most β-carotene, most flavonoids, and highest total chlorophyll. Thus, our findings support a predator-in-first augmentation approach for management of TLM.

Ovoviviparity in platyhelminth life-cycles

Parasitology ◽  
1983 ◽  
Vol 86 (4) ◽  
pp. 161-196 ◽  
Author(s):  
R. C. Tinsley
Keyword(s):  
Time Delay ◽  
Population Growth ◽  
Schistosoma Mansoni ◽  
Larval Development ◽  
External Environment ◽  
Reproductive Potential ◽  
Life Cycles ◽  
Environmental Instability ◽  
Host Behaviour ◽  
Exogenous Nutrients

SUMMARYThe encapsulated embryos of platyhelminths may be retained and complete their developmentin uteroin a range of circumstances. However, hatching within the parent (the criterion of ovoviviparity) is relatively rare and larvae generally emerge only after deposition. Viviparity is characterized by the nutritional dependency of the unencapsulated larva upon the parent, but in several cases larvae retained within a shell also receive parental nutrients during intra-uterine development. Uptake of exogenous nutrients via shell pores occurs inSchistosoma mansonibut the eggs, which gain all the advantages of intra-uterine retention, are supported by host nutrients.Intra-uterine larval development avoids the hazards of development in the external environment and eliminates the time delay between oviposition and infection. Deposition of immediately infective offspring may be concentrated in time and space to exploit periods of host vulnerability. The control and precision of transmission is illustrated by examples in which the opportunity for invasion is restricted because of either host behaviour or environmental instability. This strategy has been an important factor in the evolution of polystomatid monogeneans, and its effectiveness is demonstrated by comparison of the life-cycles ofPolystoma integerrimumandPseudodiplorchis americanus. Ovoviviparity also increases reproductive potential in some polystomatids by extending the period of multiplication and by increasing established populations through internal re-infection. InEupolystoma alluaudi, the capacity for ovoviviparity is programmed into larval development and this regulates population growth within individual hosts.

The regulation of host population growth by parasitic species

Parasitology ◽  
1978 ◽  
Vol 76 (2) ◽  
pp. 119-157 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Population Growth ◽  
Reproductive Potential ◽  
Parasite Burden ◽  
Host Population ◽  
Parasitic Species ◽  
Regulatory Influence ◽  
Host Mortality ◽  
Parasite Reproduction ◽  
Over Dispersion ◽  
Host Parasite

SummaryThe nature of parasitism at the population level is defined in terms of the parasite's influence on the natural intrinsic growth rate of its host population. It is suggested that the influence on this rate is related to the average parasite burden/host and hence to the statistical distribution of parasites within the host population.Theoretical models of host–parasite associations are used to assess the regulatory influence of parasitic species on host population growth. Model predictions suggest that three specific groups of population processes are of particular importance: over-dispersion of parasite numbers/host, density dependence in parasite mortality or reproduction and parasite-induced host mortality that increases faster than linearly with the parasite burden. Other population mechanisms are shown to have a destabilizing influence, namely: parasite-induced reduction in host reproductive potential, direct parasite reproduction within the host and time delays in the development of transmission stages of the parasite.These regulatory and destabilizing processes are shown to be commonly observed features of natural host-parasite associations. It is argued that interactions in the real world are characterized by a degree of tension between these regulatory and destabilizing forces and that population rate parameter values in parasite life-cycles are very far from being a haphazard selection of all numerically possible values. It is suggested that evolutionary pressures in observed associations will tend to counteract a strong destabilizing force by an equally strong regulatory influence. Empirical evidence is shown to support this suggestion in, for example, associations between larval digeneans and molluscan hosts (parasite-induced reduction in host reproductive potential counteracted by tight density-dependent constraints on parasite population growth), and interactions between protozoan parasites and mammalian hosts (direct parasite reproduction counteracted by a well-developed immunological response by the host).The type of laboratory and field data required to improve our understanding of the dynamical properties of host–parasite population associations is discussed and it is suggested that quantitative measurement of rates of parasite-induced host mortality, degrees of over-dispersion, transmission rates and reproductive and mortality rates of both host and parasite would provide an important first step. The value of laboratory work in this area is demonstrated by reference to studies which highlight the regulatory influence of parasitic species on host population growth.

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