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Category: Entomology

Reproductive Success of Medicago sativa: Pollen and Resource limitation

Medicago sativa is a perennial flowering plants that belongs to a legume family.  This plant is known in forage crop, grazing, silage, green manure and cover crop.  Medicago sativa develops potential for medicinal uses and thrive mostly in an arid climate. The aim of this particular research is to determine the floral traits and pollinators visitation activities that affect pollen limitations. It also identifies possible effects of resource allocation on pollen supplementation and the impacts of pollen on flower opening.

 

Medicago sativa floral traits and pollinators

Plant reproduction is limited due to pollen resources, floral traits and pollinator activities. Medicago sativa was observed at about 120 hours by collecting pollens and nectars. The pollinator type was then noted. It was then recorded the visitation frequency and behavior of flowers based on insects as effective pollinators or occasional pollinators. The pollinators then, captured using insect nets to find out the presence of pollen grains.

 

The result shows a positive relationship between pollinators visitation frequency and the number of open flowers. It also found out that, it is more efficient for pollinators to visits opening flowers. Since, filaments of Medicago sativa will dry easily particularly in an arid regions. Moreover, flowers of Medicago sativa was completely open and the pollen released between 09:00 to 14:00 hours. Additionally, some insects identified as effective pollinators because it can collect more pollen and visit more often. However, a reduction of pollinators will decline the amount of pollens and reduced the probability of cross pollen transfer.

 

Overall, this research found out that pollen resources is the limiting factor for the reproductive success of Medicago sativa. It also shows that resource reallocation can increase pollen limitation and plants might reallocate among flowers. However, insufficient pollen deposition is typically caused by pollinators assemblage, visitation and abundance.  In which flowers is the main effects of resource limitations and pollinators plays an important role in outcrossing.

 

Source: Prepared by Joan Tura from BMC Ecology

Volume 18:28 August 29, 2018

 

 

 

 

 

 

 

 

 

 

Impacts of millennium drought on butterfly faunal dynamics

Butterflies are flying colored wing insects that vary in color and pattern from individual to another individual. It has wings covered with overlapping rows of scales. Most of butterflies have developed mechanisms to   avoid predators making disguise coloration blending like leaf or bark of the tree. Some releases chemicals as a defense mechanism wherein butterfly evolved to have toxic chemicals. But recent finding due to extreme weather events and trend linked to ongoing anthropogenic climate change species shifts its dynamics. Droughts occur more often in larger spatial scale which has an effect on insects. Generally, drier and warmer climatic conditions have an impact either positive or negative to insect populations. The aim of this research is to address the knowledge gap using multi-decadal dataset of 163 butterfly species. All of this butterflies experienced millennium-scale drought.

 

Impacts of droughts on Butterflies

To know the faunal dynamics, investigation of phenology, species richness and diversity with its elevation gradient has been conducted. In which linear model used to understand differential sensitivity of butterflies to climate change at low and high elevation. A decade of dataset of 163 butterfly species across elevational gradient in Northern California has been considered. Results showed that a prolonged shift towards spring flight during drought years and change in phenology is evident across elevations. It also happened that the total flight window expanded at lower elevations while at higher elevation shifted and compressed. This leads the notion that fewer overall flight days at higher sites.

 

The millennium drought in California created across site with elevation-specific changes in flight windows and species richness. This resiliency reveals that lowest elevations are less detrimental than biotic-abiotic association at higher elevations. Most of the researchers hypothesized a mismatch between trophic levels as a result of climate change. But, results of butterflies from low elevation would suggest that at consumer trophic level need not always have negative impacts. Additionally, species at lowest elevations have access to agricultural lands though irrigation does not correlate the population dynamics during drought. Thus, there is a possibility that low elevation population buffered by irrigated crops or agricultural margin during drought.

 

Indeed, that at high elevation butterflies declined in number and become sensitive to dry years with warmer temperatures. Contrary to the theory that mountains offer microclimatic refugia and adapt species for climatic changes. It has been known that high latitude environments are warming faster with negative consequences to several species. But positive or have a neutral effect for other species. Consequently, this research suggests more thorough investigation about organismal responses to extreme weather. As well as on the extent wherein different habitat type may or may not buffer species populations against climate change.

 

Source: Prepared by Joan Tura from Springer BMC Climate Changes Responses

Volume 5:3 26 January 2018

Newly Discovered Exploding Ants – Colobopsis explodens

A new ant species, Colobopsis explodens, was recently identified. Similar to other exploding ant species, Colobopsis explodens is capable of bursting their body to kill or injure its foe in an effort to defend the nest. It will be used as a model species to lay the groundwork for more research on exploding ants.

 

 

 

Colobopsis explodens and autothysis

Exploding behavior of C. explodens in experimental setting with a weaver ant. (Credit: Alexey Kopchinskiy CC-BY 4.0)

 

Through the collaborative effort of research teams from Austria, Brunei, and Thailand, 15 distinct species of exploding ants were recently reported and Colobopsis explodens was one of them.1 These fascinating ant species are described as exploding ants because of their uncanny ability to burst their body as they will. This self-destructing act is referred to as autothysis and these exploding ants are willing to use them in combat even as an initial resort. Minor worker ants, in particular, burst to release a bright yellow sticky liquid from their glands as a way to ward off or destroy other arthropods or animals threatening their colony.2 Apart from minor ant workers, Colobopsis explodens major workers were observed to display a fascinating defensive behavior. Furnished with huge heads, the major workers use them as plugs at the entrances of their nest to thwart the entry of invaders.2

 

 

 

Autothysis is not unique to Colobopsis explodens

Colobopsis explodens and other exploding ants are not the only insects capable of autothysis. Globitermes sulphureus termite soldiers are known for a similar suicidal behavior. They contract their abdominal walls to cause the rupture of a specialized frontal gland containing a sticky liquid in order to entangle their arthropod foes.3 Another species of termites, from the family Serritermitidae, is capable of autothysis as well. Soldier termites rupture their body inside their nest – an indication that the intent is not to kill but an effort to block tunnels to prevent invaders from entering.4

 

 

 

Colobopsis explodens as a model species

What is known about the autothysis behavior of exploding ants is that they use it to kill a foe during a single combat. The ant wraps around itself to its enemy to make sure that when it self-destructs its foe will also be killed or at least injured. The fascination shown by the research teams on exploding ants signifies that Colobopsis explodens is only the beginning of a more profound research. More explorations are foreseen as the teams plan on tracking them down and record their activities. Colobopsis explodens is selected as the model species and soon enough, its biology, chemical profile, evolution, behavior, and ecological significance will be put forth.2

 

 

 

Autothysis seen in Colobopsis explodens is just one of the various sophisticated strategies used by insects during a chemical warfare to fend off their foes. It may seem a high price to pay but these insects would not dither using it even as an initial resort. Colobopsis explodens and all the other exploding ants are a nature’s paragon of valour for their willingness to sacrifice life itself for the benefit of the whole.

 

 

 

— written by Maria Victoria Gonzaga

 

 

 

References:
1 Laciny, A., Zettel, H., Kopchinskiy, A., Pretzer, C., Pal, A., Salim, K.A., Rahimi, M.J., Hoenigsberger, M., Lim, L., Jaitrong, W., & Druzhinina, I.S. (2018). Colobopsis explodens sp. n., model species for studies on “exploding ants” (Hymenoptera, Formicidae), with biological notes and first illustrations of males of the Colobopsis cylindrica group. ZooKeys 751: 1-40. https://doi.org/10.3897/zookeys.751.22661
2Pensoft Publishers. (2018, April 19). New ant species from Borneo explodes to defend its colony. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2018/04/180419131116.htm
3 Bordereau, C., Robert, A., Van Tuyen, V., & Peppuy, A. (1997). “Suicidal defensive behavior by frontal gland dehiscence in Globitermes sulphureuS Haviland soldiers (Isoptera)”. Insectes Sociaux. 44 (3): 289–297. doi:10.1007/s000400050049
4 ŠobotnÍk, J., Bourguignon, T., Hanus, R., Weyda, F., & Roisin, Y. (2010). “Structure and function of defensive glands in soldiers of Glossotermes oculatus (Isoptera: Serritermitidae)”. Biological Journal of the Linnean Society 99 (4): 839–848. doi:10.1111/j.1095-8312.2010.01392.x

Nest Architecture Development of Grass-Cutting Ants

Atta bisphaerica are group of grass cutting ants that normally found at the Cerrado biome particularly in Brazilian savanna. It is an ancient biome comprising thousands species of plants, animals and fungi. Atta bisphaerica nest are visible externally with mound of loose soil showing a large number of holes inside. In which tunnels are made up in various diameter and shapes to interconnect the chambers allowing traffics among the ants. The tunnels exit through landfill where the ants transport soil from excavations and cut leaves towards opening of nest holes. However, very little is known about Atta bisphaerica architecture development. Thus, this research investigates the nest of Atta bisphaerica from Sao Paulo Brazil.

 

Internal architecture of  Atta bisphaerica

The depth and dimension of chambers were measured after digging using molds of cement to see the actual internal structures. The length, width and height of the chambers and tunnels were also calculated. Wherein lateral development of the nests increased over time but the depth shows no changes. At 14 months  the depth ranges from 1.2m-2.0m and at 18 months it ranges from 1.3m-2.9m. On the other hand Atta bisphaerica chambers that have fungus garden incorporated with plants are found at the soil surface. Signifying the adaptations of the species to withstand in varied soil environment. Since nest are usually found at an open space with the presence of direct sunlight.

 

Moreover,  Atta bisphaerica choose the best location in terms of temperature and humidity. With regards to the internal tunnels there were increased in width over time. As well as, the dimensions of chambers augmented because of colony growth and the flow of workers inside the nest. In addition, the narrow tunnel serves as the communication between larger tunnels. There is also circular and elliptical tunnel that has been observed.

 

The architectural nest of Atta bisphaerica differ at ages probably because of temperature and humidity of the soil. And the increased numbers of chambers over time is due to an increased in population sized inside the colony. Also the width of the tunnel enlarged because of the higher flow of workers. Indeed, this research contributes to the nest architectural development of grass-cutting ants Atta bisphaerica.

 

Source: Prepared by Joan Tura from Revista Brasileira de Entomologia

Volume 62, Issue 1, January–March 2018, Pages 46-50