Population Dynamics Features of Willow-feeding Aphids

Abstract

Willow-feeding aphid colonies were sampled on scattered trees (Salix alba) from April until November, in 1999. The collected individuals belonged to 9 aphid species of 3 families (Lachnidae, Chaitophoridae, Aphididae). The aphid populations showed two peaks in May and in October. The indirect negative effect of the rainfall seems to be responsible for this temporal pattern. The Shannon diversity also exhibited spring and autumn peaks during the year. The willow-feeding aphid guild seasonally rearranged, different species were dominant in each period. Four types of population dynamics of the 9 species were established based on the abundance changes. The time of appearance of different morphs in two dominant species was compared, they belonged to Pterocomma genus. In spring, there were uncoordinated schedule in the development of populations of P. pilosum konoi and P. rufipes, the different morphs of P. pilosum konoi increased earlier. In autumn both species reached their peaks simultaneously, but there were fewer individuals of P. pilosum konoi for a longer time. This species was more vulnerable to aphid parasitoids in each season.

Effects of Aphicides on Pecan Aphids and Their Parasitoids in Pecan Orchards

“…A previous study by Kaakeh and Dutcher found a significant reduction in aphid numbers collected post-rainfall compared to pre-rainfall [ 34 ]. This is in accordance with other studies in different systems [ 35 , 36 ]. This may account for the lack of a significant difference in the upper canopy in 2020 compared to 2019 as the rainfall was greater in 2020 (3 mm) compared to 2019 (0.06 mm).…”

Trophobiosis in the arboricolous ant Liometopum microcephalum (Hymenoptera: Formicidae: Dolichoderinae)

“…We assume this was due to the low population densities of aphids at the beginning of the observation period. We have no data on aphid dynamics in this area but substantial increases in the abundance of tree-dwelling aphids from April to May are recorded for temperate regions, for instance, by Sequeira & Dixon (1997), Jarošík & Dixon (1999), Molnár (2003) and Durak (2008). However, we have no explanation for the high gaster mass and low concentration of sugars in workers returning to nest trees in April compared to the other groups of workers (Figs 3, 5, 7).…”

Honeydew production by the giant willow aphid (Tuberolachnus salignus, Hemiptera: Aphididae) and its effect on foraging yellowjackets (Hymenoptera: Vespidae)

“…Previous studies suggested that population dynamics of the GWA is highly variable between years, with insects observed on willows for up to 20 weeks. 17,19 For instance, in other temperate parts of the world, GWA populations peak in mid-autumn, 31 and remain visible even through winter months. 19,32 Their presence in willows during winter seems to depend, among other factors, on willow cultivar, as adults were observed overwintering in Salix lasiandra Benth.…”