Climate warming may increase aphids' dropping probabilities in response to high temperatures.

Area of Science:

• * Entomology
• * Animal Behavior
• * Climate Change Biology

Background:

• * Aphid dropping behavior is primarily studied as an anti-predator response.
• * High temperatures due to climate warming present a novel stressor for aphids.
• * The impact of heat stress on aphid dropping behavior is not well understood.

Purpose of the Study:

• * To investigate if aphids drop off host plants to avoid high temperatures.
• * To define and measure drop-off temperature (DOT) as a critical threshold for heat-induced dropping.
• * To determine how short-term acclimation (starvation, temperature exposure) affects aphid DOT.

Main Methods:

• * Gradual increase in ambient temperature to determine the critical DOT for Sitobion avenae.
• * Manipulation of starvation duration (0, 6, 12 hours) and prior heat exposure.
• * Observation of aphid movement and muscle control before and after dropping.

Main Results:

• * Aphids exhibit pre-drop movement, suggesting active thermoregulation, not passive knockdown.
• * Starvation for 12 hours increased DOT, indicating a trade-off between thermoregulation and energy acquisition.
• * Higher temperatures and longer exposure times significantly reduced DOT, confirming avoidance of heat stress.

Conclusions:

• * Dropping is a behavioral thermoregulation strategy for aphids facing heat stress.
• * Aphid DOT is modulated by acclimation factors like starvation and prior heat exposure.
• * Increased frequency of high temperatures due to climate warming may enhance aphid dropping, affecting population dynamics.