Abstract
Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with two aphid species and were evaluated at 7, 14, 28, 35, 42, and 49 days after the infestations. Mathematical models were used to fit the population dynamics of two aphid species. There were good fits for aphid dynamics by mathematical model over time. The highest population peak of both species A. gossypii and A. craccivora was found in the sole crops, and the lowest population peak was found in crop system t2. These results are important for integrated management programs of aphids in cotton and cowpea.
Highlights
The aphids Aphis gossypii Glover (Ramalho et al 2012) and Aphis craccivora Koch (Hemiptera: Heteroptera: Aphididae) (Moraes and Ramalho 1980) are serious crop pests in Brazil
The decay was smoother for the aphids on cotton intercropped with cowpeas, compared to a sole crop, probably because the intercropping systems reduced the aphid pressure compared to the sole system
In the sole cotton (t4), t1 and t3 crop systems, wingless A. gossypii peaked at 42 days, while in crop system t2 the cotton aphid peaked at 35 days after the plant infestations
Summary
The aphids Aphis gossypii Glover (Ramalho et al 2012) and Aphis craccivora Koch (Hemiptera: Heteroptera: Aphididae) (Moraes and Ramalho 1980) are serious crop pests in Brazil. These insects directly damage the plants by sucking the phloem, and indirectly by virus transmission and excretion of excess carbohydrates from their diet of can reach high abundances in warm-temperate and tropical regions (Gutierrez et al 1974). The population dynamics of aphids can be affected by seasonal changes in weather conditions, physiological characteristics of the host plant, farming methods, and management practices (Sequeira and Dixon 1997). Some crops may deter while others may attract sucking insects, and local variation in resource quality profoundly influences the overall population dynamics (Kadam et al 2014, Riolo et al 2015)
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