Blog Archives

Help the Baltimore Checkerspot Butterfly

4/23/2015

The state insect of Maryland—the Baltimore Checkerspot butterfly—only exists in small, isolated areas in the state, mostly in Western Maryland. One of the most vividly colored butterflies with its bright orange, white and black pattern, experts worry that the butterfly, once fairly common, may disappear entirely from the state.

Researchers at the University of Maryland have launched a crowdfunding campaign to raise $5,000 to help bring the state insect back to College Park.

Spring 2015 Colloquium: Greg Davis

4/17/2015

Post by Justin Rosenthal and Nathalie Steinhauer

The Challenges of Optional Sex: the case of reproductive polyphenism in aphids

Insects lay eggs, right? Well, in aphids, a speciose family of the Sternorrhyncha, females actually have the option of laying eggs or producing live young from embryos (instead of laying eggs). This is an example of reproductive polyphenism. Polyphenism is the ability of some organisms to adapt their phenotypes in response to environmental cues (Figure 1, from Ogawa and Miura 2014). In aphids the two reproductive strategies are a response to changes in photoperiod (day length) and this polyphenism is observed ubiquitously in these insects. In their life cycle, after having survived the winter as frost-resistant eggs, founder females reproduce asexually birthing live young that will produce further asexual females. Asexual females are all about high reproductive rates and dispersion. Those asexual females actually exhibit a second type of polyphenism in that some of them can develop wings promoting dispersion when its current location is experiencing crowded conditions. As day length gets shorter, indicating the coming of winter, sexual egg-laying females are produced (Figure 1). But how are those changes mediated by the environmental signals and how does the system switch from sexual to asexual reproduction?

In last week’s colloquium, Gregory Davis illustrated the complexity of deciphering the mechanisms behind reproductive polyphenism using aphids as his model. Much of this work is available in his most recent review paper (Davis, 2012 ). He believes that such a novelty may have developed because an initial, slight change in morphology may have stimulated a modification of life history, with changes in life history feeding back to further changes in morphology, continuously playing off each other until obvious changes in body structure and development evolve.

Spring 2015 Colloquium: Rodriguez-Saona

4/10/2015

An Agricultural Balancing Act:
A look at the biological control consequences of crop domestication

By Lauren Hunt and Jessica Grant

Ecological theories and models that attempt to explain interactions between plant, herbivore, and predator are innumerable. But just how accurate can these theories be? How many factors can be feasibly fitted to a model without making it cumbersome? What major variables are missing from these interaction evaluations? Dr. Rodriguez-Saona cites one key aspect of agro-ecosystems that has often been ignored: anthropogenic effects of crop selection.

In terms of biological control, there are numerous top-down and bottom-up factors that play a role in the dynamic balance between plants and herbivores. Top-down factors are regulating mechanisms in which herbivore population numbers are controlled through upper trophic level organisms such as predators, natural enemies and parasitoids. In response to a lack of mobility, plants have developed an array of bottom-up mechanisms with which they can resist attack. Bottom-up controls are synergistically balanced with top-down controls in natural systems for overall suppression of herbivore populations. Plants utilize bottom-up mechanisms directly, through chemical and physical features used to resist damage and indirectly, by signaling to predators of an ongoing attack. These cries for help are in the form of volatiles (herbivore-induced plant volatiles, or HIPVs) that predators and parasitoids can respond to, finding food and reproductive hosts while simultaneously defending the plant. The HIPVs influence both bottom-up and top-down controls in this tri-trophic interaction.

Beware of Invading Ants During Spring!

4/2/2015

Mike Raupp discusses the most common invader of households in the spring, odorous house ants!

Ants are among the most common house-invaders during the spring. (Courtesy Michael Raupp/University of Maryland)

While some people find the idea of ants in their kitchen repulsive, Raupp says they’re more of a nuisance than anything else. They don’t bite, sting or spread diseases.

“Ants are clean. Ants are not important distributors of microbes or disease-causing agents,” Raupp says.

Read more about this article at WTOP!

Spring 2015 Colloquium: Ted Schultz

4/2/2015

“Symbiotic Evolution and Species Discovery in Fungus-Farming Ants”

Dr. Ted Schultz has trekked the Americas in search of precious buried treasure; fungus-farming ants. Although these anthropomorphic creatures are not typically what we consider to be of monetary importance, they reveal a wealth of information about coevolution and symbiotic relationships. Fungus farming ants, like human farmers, cultivate their own food in gardens that are remarkably well cared for (Schultz, et al. 2015). However, unlike humans, fungus-farming ants have an obligate mutualism with their species-specific fungus. Imagine if we could only cultivate one type of food and that food could only survive via human agriculture. Dinner as we know it would be an entirely different experience.

Tracking these ants to their colony requires patience and dedication. To start, Dr. Shultz baits the ants with Cream of Rice and waits for an ant of interest to approach and take a bit of bait to bring back to the colony. Using a white food source makes it easier to spot the ants as they travel through the leaf litter, but it is still a difficult task. Once the ant leads him to a colony entrance, the digging starts. Fungus-farming ant colonies may be over 3 meters deep and digging requires several determined entomologists. Walls that cave in and sandy soils are no deterrents when the prize is a sample of the fungus garden and the ants that tend to it.