Evaluation of traps used to monitor southern pine beetle aerial populations and sex ratios

Abstract

1 Various kinds of traps have been employed to monitor and forecast population trends of the southern pine beetle (Dendroctonus frontalis Zimmermann; Coleoptera: Scolytidae), but their accuracy in assessing pine-beetle abundance and sex ratio in the ®eld has not been evaluated directly. 2 In this study, we used¯uorescent powder to mark pine beetles emerging from six isolated infestations. We then compared estimates of total abundances and proportions of males emerging from within each infestation to the estimates from three types of traps: passive sticky traps (2, 5, 10 and 20 m away from the source of beetles), multi-funnel traps baited with pine beetle attractants (100 m away) and pine trees baited with attractants (also 100 m away). 3 We found that the proportion of males captured in traps was signi®cantly affected by the type of trap used. 4 Within an infestation, equal proportions of males and females were marked (0.53 6 0.02 males; mean 6 SE), but the proportions captured in trap trees and passive traps were more female biased (0.42 6 0.03 and 0.46 6 0.01 males, respectively). On the other hand, funnel traps provided an estimate of the proportion of males that was nearly identical to the proportion from within infestations (0.51 6 0.03). 5 Numbers of marked beetles captured in traps were uncorrelated with the numbers of marked beetles emerging from the focal infestations. This suggests that traps positioned around an infestation may not be effective at estimating relative abundances of beetles within the infestation.

Responses of <I>Rhyzopertha dominica</I> (Coleoptera: Bostrichidae) to Its Aggregation Pheromones as Influenced by Trap Design, Trap Height, and Habitat

“…This is in agreement with previous observations on several other stored-product and wood-boring beetles that use male-produced aggregation pheromones (Plarre and Vanderwel 1999, Cronin et al 2000, Phillips et al 2000, De Groot and Nott 2001. One possible explanation is that the primary function of male-produced pheromones in R. dominica is to attract females as potential mates, but other males exploit the signal for locating assembled females and resources (Landolt 1997, Phillips 1997.…”

Factors influencing dispersal by flight in bark beetles (Coleoptera: Curculionidae: Scolytinae): from genes to landscapes

“…Beetle capture in semiochemical-baited traps, however, does not reflect beetle movement during the initial non-oriented phase of flight dispersal (Franklin and Grégoire 1999). These methods are reliable monitoring tools (Evenden and Silk 2016), but trap capture does not always reflect stand-level population density (Cronin et al 2000).…”

Sampling procedures and adult sex ratios in spruce budworm

“…In extreme examples, these differences can frustrate attempts to collect one gender or the other (and in the process greatly frustrate the entomologist; e.g., Gibson, 1878). Mark-recapture studies (Cronin et al, 2000;Stoks, 2001) have illustrated the occurrence of sampling artefacts in sex ratio assessments and the importance of understanding the distinct behaviour of males and females for the interpretation of field data.…”