Does weather influence aphid populations?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.The weather has a significant impact on aphid outbreaks due to its numerous direct and indirect effects. Temperature determines the rate of reproduction, while rainfall physically purges colonies by limiting their escape. Drought stresses the plants and increases their susceptibility. I have noticed a significant increase in the number of infested colonies following warm, dry streaks in my orchard.
Temperature Effects
- 65-80°F (18-27°C): Optimal reproduction
- Below 50°F (10°C): Metabolic slowdown
- Above 90°F (32°C): Increased nymph mortality
Precipitation Influence
- Heavy rain: Physically washes off colonies
- Light rain: Boosts plant growth increasing food
- Humidity: Affects fungal pathogen spread
Drought Consequences
- Stressed plants produce nutrient-rich sap
- Reduced predator activity in arid conditions
- Increased winged forms for migration
Winter conditions are conducive to seasonal outbreaks. Temperatures in the above-freezing range allow for the survival of overwintering eggs and nymphs. Each rise of 5°F (- 15°C) in winter average temperatures may theoretically increase the survival of these stages by about 25% for every 5°F increase. This explains the early and more abundant infestations in territories with warmer winters.
Weather patterns in spring are a key factor in determining the severity of potential infestations. Hot weather in the spring causes nymphs to develop in 5 days rather than 14 days. Dry weather favors aphids by limiting the fungal pathogens that naturally control them. I record soil moisture and soil temperature to predict potential infestations weeks in advance.
Tailor management to local weather patterns. Add rain gauges to monitor rainfall patterns. Use soil thermometers to monitor temperatures in the root zone. Introduce predators predicted to cause warm periods. Apply kaolin clay sprays during drought to discourage feeding. This climate-responsive strategy prevents damaging outbreaks.
Read the full article: Aphid Life Cycle: Stages and Secrets
