Oviposition Traps to Survey Eggs of Lambdina fiscellaria (Lepidoptera: Geometridae)

Abstract

Outbreaks of the hemlock looper, Lambdina fiscellaria (Gueneé), are characterized by rapid increase and patchy distribution over widespread areas, which make it difficult to detect impending outbreaks. This is a major problem with this insect. Population forecasting is based on tedious and expensive egg surveys in which eggs are extracted from 1-m branches; careful observation is needed to avoid counting old unhatched eggs of previous year populations. The efficacy of artificial substrates as oviposition traps to sample hemlock looper eggs was tested as a means of improving outbreak detection and population forecasting. A white polyurethane foam substrate (1,095 lb/ft3) used with the Luminoc insect trap, a portable light trap, was highly efficient in sampling eggs of the hemlock looper. Foam strips placed on tree trunks at breast height were less efficient but easier and less expensive to use for the establishment of extensive survey networks. Estimates based on oviposition traps were highly correlated with those obtained from the 1-m branch extraction method. The oviposition trap is a standard, inexpensive, easy, and robust method that can be used by nonspecialists. This technique makes it possible to sample higher numbers of plots in widespread monitoring networks, which is crucial for improving the management of hemlock looper populations.

Remote sensing of forest pest damage: a review and lessons learned from a Canadian perspective

“…Early -mid-July coinciding with red-brown foliage Kulman et al (1963), DeBoo and Hildahl (1968), , Ives and Wong (1988), Cadogan (1995) Hall et al Coulson and Witter (1984), Martineau (1984), Mills and Räther (1990), Raske et al (1995), MacLean and Ebert (1999), Hébert et al (2003) Partial or full defoliation of foliage. The degree of foliage loss governs severity these attack stages is highly variable and depends upon a number of factors, including attack density and timing, tree moisture and condition, tree species, as well as site-specific factors .…”

“…A challenge in detecting and monitoring outbreaks is that hemlock looper populations can grow rapidly, persist for one or two years, and then collapse, with host tree mortality occurring even in the first year of attack (Harris et al 1982;Delisle and Hébert 2012). The distribution of damage can be patchy over widespread areas, which hampers the detection of impending outbreaks (Hébert et al 2003) from both aerial and ground surveys and remote sensing perspectives. Severe outbreaks, however, are easier to detect, as they result in high levels of mortality over limited but well-defined areas (Mills and Räther 1990).…”

Lichen-plant interactions

“…On the other hand, corticolous lichens, regardless of their hyphal penetration, may indirectly affect their plant substrate by harboring insects. It is worth noting that epiphytic lichens provide favorable conditions for the oviposition of the hemlock looper Lambdina fiscellaria (Lepidoptera), which is a devastating defoliator of coniferous forests in North America (He´bert et al 2003). However, in many cases, abundant corticolous colonization is a consequence and not a driving factor of defoliation, as exemplified by the Bryoria colonization of defoliated, moribund parts of black-spruce trees infested by spruce budworms Choristoneura fumiferana (Lepidoptera; Simard and Payette 2003).…”

Sampling strategies and density–defoliation relationships for the pale-winged gray moth, Iridopsis ephyraria, on mature eastern hemlock

“…Prior to pupation in mid-July 2005, white polyurethane foam (mean pore size = 0.53 mm) was cut into 2.5 cm  17 cm  14 cm blocks, as in Hébert et al (2003), and stapled to the bole 1.5 m from the ground on 30 trees at each site. The white colour of the foam mimics lichens commonly coating hemlock boles in this area, although the colour faded to amber after 2 weeks.…”

“…White polyurethane foam oviposition traps, which have been used successfully to estimate hemlock looper (Lambdina fiscellaria Guenée) egg densities on balsam fir, Abies balsamea (L.) P. Miller (Hébert et al, 2003), were placed on host trees to estimate egg densities of I. ephyraria. Based on the assumption that first-instar larvae emerging from eggs laid on the lower bole would climb upwards to the foliated crown immediately following egg hatch, we also used bands of ''sticky tape'' placed around the lower bole of host trees, to estimate firstinstar densities.…”