Tritrophic Interactions among Arthropod Natural Enemies, Herbivores and Plants Considering Volatile Blends at Different Scale Levels.

Herbivore-induced plant volatiles (HIPVs) are released by plants upon damaged or disturbance by phytophagous insects. Plants emit HIPV signals not merely in reaction to tissue damage, but also in response to herbivore salivary secretions, oviposition, and excrement. Although certain volatile chemicals are retained in plant tissues and released rapidly upon damaged, others are synthesized de novo in response to herbivore feeding and emitted not only from damaged tissue but also from nearby by undamaged leaves. HIPVs can be used by predators and parasitoids to locate herbivores at different spatial scales. The HIPV-emitting spatial pattern is dynamic and heterogeneous in nature and influenced by the concentration, chemical makeup, breakdown of the emitted mixes and environmental elements (e.g., turbulence, wind and vegetation) which affect the foraging of biocontrol agents. In addition, sensory capability to detect volatiles and the physical ability to move towards the source were also different between natural enemy individuals. The impacts of HIPVs on arthropod natural enemies have been partially studied at spatial scales, that is why the functions of HIPVs is still subject under much debate. In this review, we summarized the current knowledge and loopholes regarding the role of HIPVs in tritrophic interactions at multiple scale levels. Therefore, we contend that closing these loopholes will make it much easier to use HIPVs for sustainable pest management in agriculture.

Plant Volatiles and Herbivore Induced Plant Volatiles from Chili Pepper Act as Attractant of the Aphid Parasitoid Aphelinus varipes (Hymenoptera: Aphelinidae).

Plants have evolved a number of different chemical defenses, covering nearly all classes of (secondary) metabolites, that represent a major barrier to herbivory: some are constitutive; others are induced after attacks from herbivores (HIPVs) and may elicit the attraction of predators and parasitoids. Here, we studied how the female solitary endoparasitoid Aphelinus varipes responds to plant and host aphid volatiles in a series of experiments on five commercially important vegetables that were either healthy or infested with the aphid Myzus persicae: chili pepper, eggplant, crown daisy, Chinese cabbage and cabbage. The results for the olfactory responses of A. varipes showed that the presence of M. persicae increased the attraction of the endoparasitoid to the infested plants. In a second experiment, volatiles from highly attractive and repellent plants were obtained via headspace collection to investigate volatiles from healthy and aphid-damaged plants. The results for the differences in volatile profiles in response to aphid infestation in chili pepper cultivar were dominated by the volatile blends, including α-pinene, decanal and phthalic acid, while in cabbage they were dominated by isophorone. Moreover, when HIPVs with different concentrations were compared, α-pinene at a dose rate of 100 ng/µL attracted more parasitoids, and the comparison was useful to understand the mechanisms of plant secondary volatiles during aphid infestation and to provide new resources to control this insect pest. Overall our study shows how HIPVs can bolster tritrophic interactions by enhancing the attractiveness of parasitoids.

Host-Plant Variations Affect the Biotic Potential, Survival, and Population Projection of Myzus persicae (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), a polyphagous insect pest is a major threat to a wide range of crops worldwide. Aiming to evaluate the life history traits of M. persicae, feeding on different host plants, we used five vegetables: cabbage, Brassica oleracea (Brassicaceae); chinese cabbage, B. rapa (Brassicaceae); chili pepper, Capsicum annum (Solanaceae); crown daisy, Chrysanthemum coronarium (Asteraceae); and eggplant, Solanum melongena (Solanaceae). TWOSEX-MSchart software was used for the statistical analysis about the age-stage, two-sex life table theory. The highest fecundity (69.65 individuals) rate of M. persicae, intrinsic rate of increase (r = 0.425 d-1), finite rate of increase (λ = 1.531 d-1), net reproductive rate (R0 = 69.65 offspring), and shortest mean generation time (T = 9.964 d) were recorded on the chili pepper plant. Whereas, lower fitness occurred on cabbage. The findings attained from population growth parameters indicate that chili pepper is the most susceptible plant, while cabbage is resistant to aphids. Population projection results also supported this statement, as the final total population size on cabbage was significantly lower than other plants. The reported information would be useful for devising integrated pest management programs, particularly those involving M. persicae. This information also suggests the adaptability of M. persicae causing economic damage to these vegetable cultivars.

Possible Potential Outcomes from COVID-19 Complications on Testes: Lesson from SARS Infection.

Coronavirus infection disease-2019 (COVID-19) gained worldwide fame after deadly outbreak in China and its subsequent spread to many countries. So far, COVID-19 is not fully contained, and new cases are arising on daily bases in various countries. Due to zoonotic nature and human-to-human spread, COVID-19 is considered pandemic with more causalities in developing countries. Full genome analysis revealed its resemblance with severe acute respiratory syndrome (SARS) virus with minor variation in non-structural proteins. Both viruses use the common angiotensin converting enzyme (ACE2) receptor to attach to the epithelial cells of the target organs. Currently, COVID-19 patients are treated with drugs that are used for lungs infections. However, ACE2 has high expression in other human organs such as kidney and testes. Thus, it is assumed that, like SARS, it may have adverse effects on other vital organs, which have dominant expression of ACE2. In testis, SARS affected patients displayed peritubular fibrosis, extensive germ cell disruption, damage of blood-testis barrier integrity and more frequent occurrence of apoptosis. Here, we critically discuss the possible adverse effects of COVID-19 on the testes of patients along with future precautions to overcome the complications of reproductive organs. Key Words: COVID-19; SARS; ACE2, Testes.