This is the twelfth short news article written by students, during the professional development class of Spring 2024, about each other's research.

Student Spotlight: Mahendra Pawar

By James Abendroth

Aphids, a notorious nuisance to all plant enthusiasts, can be incredibly difficult to manage. This is due to the remarkable ability of this insect to go from a lone wolf to a massive population, in a relatively short period of time. Coincidentally, many aphid species have become quite resilient to pesticides, due to a combination of their unique life history and excessive usage of pesticides leading to resistance. Left unmanaged, aphids can stunt and potentially destroy the plants they feed upon through mechanical damage following high infestations. Aphid infestations can also indirectly impact plants through the transmission of lethal plant viruses that they harbor. One way to control aphids is to increase populations of predators, such as lady beetle (Harmonia axyridis), that feed on them.

Historically, most research on predator-prey interactions has focused on consumptive effects – or the actual consumption of the prey by the predator. Non-consumptive effects are implications for prey survival and performance that result from the mere “risk” of predation. For example, many organisms avoid predation by changing behaviors where the prey may spend more time hiding than feeding which leads to a trade off for growth and development. Importantly, non-consumptive effects can potentially be as important in their effects on a prey population compared to consumptive effects. In support of this, prior research performed by the Hermann lab has observed that aphids will produce fewer offspring, feed less, and attempt to completely avoid plants in which they detect the lady beetle odor.

Due to this, novel strategies to combat this pest are desired greatly, and Mahendra Pawar, a PhD student in Professor Sara Hermann’s research group in the Department of Entomology at Penn State, is investigating such a strategy. The focus of this research is on understanding how lady beetle (Harmonia axyridis) cues can influence aphids in agroecosystems.

Mahendra states that this work will “help us better understand how aphid behavior and physiology are influenced by predation risk”.

Mahendra also predicts that virus transmission of aphids could also be influenced when under duress from lady beetle odor. This prediction, if true, would be a huge boon to further mitigating the damage this pest can cause, as aphids alone are responsible for over 1/4th of all plant viruses vectored by insects!

Mahendra hopes that his work will highlight the significance of non-consumptive effects of predator-prey interactions in agroecosystems, demonstrating the potential for this strategy to be integrated into existing biocontrol strategies for more sustainable agriculture. Through the identification of the specific chemical constituent of the lady beetle odor blend that decreases aphid success, we can determine how to strike fear in these pests!

Mahendra Pawar is a PhD student in the entomology department, advised by Professor Sara Hermann.