Population Dynamics of Aphids on Cereals: Digging in the Time-Series Data to Reveal Population Regulation Caused by Temperature

Abstract

Aphid populations show periodic fluctuations and many causes are attributed to their dynamic. We investigated the regulation by temperature of the aphid populations composed of Metopolophium dirhodum, Sitobion avenae, and Rhopalosiphum padi on winter wheat using a 24 years long time series data. We computed the sum of daily temperatures above 5°C, the threshold temperature for aphid development, and the sum of daily temperatures within the [0(threshold for wheat development),5] °C interval. Applying Generalised Additive Model framework we tested influences of temperature history expressed via degree days before the start of the aphid immigration on the length of their occurrence. We aimed to estimate the magnitude and direction of this influence, and how far to the past before the start of the aphid season the temperature effect goes and then identify processes responsible for the effect. We fitted four models that differed in the way of correcting for abundance in the previous year and in specification of temperature effects. Abundance in the previous year did not affect the length of period of aphid population growth on wheat. The temperature effect on the period length increased up to 123 days before the start of the current season, i.e. when wheat completed vernalization. Increased sum of daily temperatures above 5°C and the sum of daily temperatures within the [0,5] °C interval both shortened the length of period of aphid population growth. Stronger effect of the latter suggests that wheat can escape from aphid attacks if during winter temperatures range from 0 to 5°C. The temperature influence was not homogeneous in time. The strongest effect of past temperature was about 50 to 80 and 90 to 110 days before the beginning of the current aphid season indicating important role of termination of aphid egg dormancy and egg hatching.

Temporal Changes in Cereal Aphids (Hemiptera: Aphididae) Populations in Northern Rio Grande do Sul, Brazil

“…Temperature is also another dominant abiotic factor. For aphids temperature has been shown to be a reliable indicator of future population growth (Brabec et al, 2014;Finlay & Luck, 2011). Mild temperatures, 18-25 °C, and rain shortages create conditions that are ideal for aphid reproduction and development (Gassen, 1984).…”

Length of prematurity period in wheat cultivars determines maximum cereal aphid abundance

“…where: x s -standardised value of mean aphid abundance in a particular replicate; x o -experimental value of aphid abundance in a particular replicate; x a -average; s x -standard deviation of the aphid abundance values on all replicates together (Hendl 2009) Standardisation compensated for the important annual variation in aphid abundance (Wetzel 2004;Brabec et al 2014), which would conceal cultivar differences. The standardised values (x s ) were regressed on flowering time as a proxy for the cultivar-specific length of vegetation period, using second-order polynomial regression y = a + bx s + cx s 2 .…”

“…The maximum number of aphids on a crop stand (population peak) is determined by three population parameters: (i) initial number of immigrants, (ii) rate of population increase, which is determined by female developmental time and fecundity, and (iii) duration of the period of population increase, which is the time elapsed from immigration to the population peak (Honek 1991c;Honek et al 2006). The effects of immigrant numbers (Basky & Harrington 2000;Klueken et al 2009) and of factors determining the population growth rate, host plant quality (Honek 1991b;Honek & Martinkova 2004b), temperature (Dean 1974;Brabec et al 2014), aphid reproduction rate (Simon et al 1991;Sengonca et al 1994), and presence of natural enemies (Leslie et al 2009;Kerzicnik et al 2010) are well studied. In contrast, factors that determine the duration of the period of aphid population increase have not been sufficiently addressed.…”

“…In Central Europe, aphid migration to cereals takes place in May. Immigration is timed based on the thermal response of overwintering aphid populations and depends on winter and spring weather (Klueken et al 2009;Brabec et al 2014). After immigration, aphids continue to benefit from host plants as long as photosynthetic products are translocated.…”

Population dynamics of Aphis gossypii Glover and in sole and intercropping systems of cotton and cowpea

“…Munyuli (2009) reported that in comparison with control treatments, biological control of A. craccivora with predators increased yields by up to 66% for cowpea Vigna unguiculata (Linnaeus) Walp. Aphid populations can show periodic fluctuations (Brabec et al 2014). 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).…”