Performance and population growth rate of the cotton aphid, and associated yield losses in cucumber, under different nitrogen fertilization regimes

Abstract

Performance and population growth rate of the cotton aphid Aphis gossypii Glover, and the yield losses inflicted by that pest, were studied in relation to varying nitrogen fertilization levels (90, 110, 150 and 190 ppm) on cucumber, Cucumis sativus L., under greenhouse conditions. The results showed that some plant variables, including leaf biomass, water and nitrogen content, increased at higher levels of nitrogen fertilization. Aphids developing on cucumber plants receiving the highest nitrogen fertilization had a significantly shorter development time and produced more offspring per capita than aphids subjected to the other regimes. However, no significant differences were observed in juvenile survivorship under different nitrogen treatments. Aphid adult body weight and mean relative growth rate (MRGR), as well as the intrinsic rate of natural increase (r m ), were positively correlated with nitrogen fertilization levels in the treated plants. Additionally, aphid abundance and population growth rate (r) were significantly influenced by interaction between nitrogen fertilization level and sampling date. Plant yield was significantly affected by the interaction between nitrogen fertilization rate and aphid presence. In the absence of aphids, plant yield increased linearly with higher nitrogen fertilization; however, in the presence of aphids yield decreased linearly with nitrogen fertilization, the lowest yield being produced by plants fertilized with 190 ppm nitrogen. We discuss the results in relation to aphid population dynamics and management.

How the aphids got their spots: predation drives self‐organization of aphid colonies in a patchy habitat

“…To determine how the deviation from the log‐normal distribution arose, we calculated the daily rate of population increase r A = ln(N t+ y + 1/N t + 1) for all aphid colonies (Turchin 2003, Obopile and Ositile 2010). We analyzed the data using time lags (y) of 1 and 5 days, which approximate the ideal colony doubling time of 1–2 days (Hosseini et al 2010), and the aphid development time of 5–7 days (Obopile and Ositile 2010, Hosseini et al 2010).…”

Response of walnut aphid populations to increasing foliar nitrogen content

“…This time period corresponds to approximately two aphid generations, approximately 19 days (Hougardy & Mills, ), and was sufficient time for the aphid populations to increase from ten individuals to 50–3000 individuals. For each walnut seedling, the instantaneous rate of increase ( r ) of the experimental populations of C. juglandicola was estimated from where N 0 = initial number of aphids and N 1 = final number of aphids (Hosseini et al ., ; Latham & Mills, ). This is the recommended method for estimating population growth rate when initial and final numbers are the measurement variables available (McCallum, ).…”

“…Aphids are important agricultural pests in many crops (van Emden & Harrington, ) and, based on observations from both natural and agricultural systems, their response to increased nitrogen can vary from positive (Cisneros & Godfrey, ; Nevo & Coll, ; Chau et al ., ; Noma et al ., ) to negative (Zehnder & Hunter, ; Hosseini et al ., ). Although most studies have been based on annual agricultural crops, aphids are also key pests in tree fruit and nut crops and far less is known about their response to increased nitrogen in tree foliage.…”

Effect of ant attendance on aphid population growth and above ground biomass of the aphid's host plant

“…To assess whether the aphid population growth rate was infl uenced by ant attendance and the initial number of aphids, the aphid's r was estimated using the following formula (Chau et al, 2005;Hosseini et al, 2010):…”

“…Therefore, based on this the average (12 individuals) initial number of aphids, and one upper (24 individuals) and one lower level (3 individuals) aphid number were chosen as the experimental treatments. In order to achieve a stable age distribution and exponential population growth from the commencement of the experiment (Vehrs et al, 1992;Hosseini et al, 2010), aphids of various ages (fi rst or second instar + third or fourth instar + adult) were transferred.…”