Using Automated Flight Mills to Manipulate Fat Reserves in Douglas-fir Beetles (Coleoptera: Curculionidae)

Williams, Wyatt; Robertson, Ian Ross

doi:10.1093/ee/37.4.850

Cited by 37 publications

(36 citation statements)

References 35 publications

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“…Sample sizes are indicated by numbers beside means, ns indicates no significant difference in condition index between individuals that died or lived within a treatment, ** indicates the difference had P \ 0.01 unclear for natural populations where body condition varies among individuals, seasons and years. Indeed, our study population had less fat upon emergence than is often observed using similar methods of fat extraction (Elkin and Reid 2005;Williams and Robertson 2008). Most beetles in our study had less than 0.3 mg of fat, whereas beetles studied by Elkin and Reid (2005) had mean values close to 1 mg.…”

Section: Discussionmentioning

confidence: 44%

“…When we starved beetles of the same cohort as those we tested for 5 days, more than 50% died within 5 days while fewer than 10% died when this treatment was used in a previous study (Elkin and Reid 2005). The mortality we observed may be more pronounced than would be seen in other populations of newly emerged beetles, but may be commonly seen later in the dispersal process after energy has been expended (Williams and Robertson 2008). The exact component of body condition index that was responsible for the relationship between body condition and tolerance of high monoterpene concentrations is unclear.…”

Section: Discussionmentioning

confidence: 59%

“…Adult bark beetles typically leave their natal tree and disperse to a new host tree for breeding. Their dispersal flight is fuelled by lipids accumulated during the larval period and energy stores decline monotonically during dispersal (Atkins 1969;Williams and Robertson 2008). Most temperate bark beetles inhabit conifer trees that have a suite of mainly lipophilic terpenoid defences (Keeling and Bohlmann 2006).…”

Section: Introductionmentioning

confidence: 99%

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Condition-dependent tolerance of monoterpenes in an insect herbivore

Reid

Purcell

2011

Arthropod-Plant Interactions

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The ability of a herbivore to tolerate plant defensive chemicals may vary with the herbivore's energetic state. We investigated the effect of body condition on the survivorship of individual mountain pine beetles, Dendroctonus ponderosae, exposed to host monoterpenes at concentrations comparable to constitutive and induced levels of defence using fumigant exposure. Body condition index was calculated as the residual mass after fitting the relationship between fresh weight and body size. Differences in survivorship among the four monoterpenes tested (a-pinene, myrcene, terpinolene and limonene) were small. Beetles with a higher body condition index survived high monoterpene concentrations better than those in poorer condition. There was no direct effect of sex, but positive effects of body size and fat content on survivorship favoured females, the sex that pioneers attacks on live trees. Higher body condition index corresponded to both higher fat content and fat-free body mass; the same conclusions about monoterpene identity and size-dependent or energy-dependent tolerance of high monoterpene concentrations held if fat or fat-free body mass were used in place of body condition index. This study highlights the need to consider insect body condition in understanding insectplant interactions.

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Section: Discussionmentioning

confidence: 44%

Section: Discussionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

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Condition-dependent tolerance of monoterpenes in an insect herbivore

Reid

Purcell

2011

Arthropod-Plant Interactions

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“…could fly up to 8 h, while the southern pine beetle (Dendroctonus frontalis Zimm.) up to 6 h; and Williams and Robertson (2008) found that 6 h of flight for Douglas-fir beetles could be achieved but at the expense of a &50% decrease in body fat. J08 suggest that beetles undergoing passive transport in the midst of thermal updrafts should expend less energy than beetles on flight mills, while Williams and Robertson (2008) note that flight mill studies might overestimate flight times in nature due to the mill supporting the beetle's body while in flight.…”

Section: Discussionmentioning

confidence: 99%

“…up to 6 h; and Williams and Robertson (2008) found that 6 h of flight for Douglas-fir beetles could be achieved but at the expense of a &50% decrease in body fat. J08 suggest that beetles undergoing passive transport in the midst of thermal updrafts should expend less energy than beetles on flight mills, while Williams and Robertson (2008) note that flight mill studies might overestimate flight times in nature due to the mill supporting the beetle's body while in flight. Given the range of measured flying times and the difficulty in assessing how laboratory studies simulate natural flying conditions, the methods developed in this paper appear to be both consistent with previous work and present a novel way of determining beetle flying times.…”

Section: Discussionmentioning

confidence: 99%

Investigation into mountain pine beetle above-canopy dispersion using weather radar and an atmospheric dispersion model

Ainslie

Jackson

2010

Aerobiologia

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Above-canopy, wind-assisted mountain pine beetle (MPB) dispersion in British Columbia (BC) is examined during the summer 2005 beetle emergence period. Above-canopy dispersion is simulated by the HYSPLIT atmospheric dispersion model using back trajectories started from locations identified by clear-air returns from the Prince George BC weather radar station. The dispersion calculations are carried out over the 10 days showing the highest intensity of clear-air returns from the 2005 emergence season. The Weather Research and Forecast (WRF) model is used to simulate the meteorological conditions during each of the 10 emergence days. Cumulative clear-air returns throughout each emergence day are used to estimate the distribution of beetle emergence times and atmospheric residence times. Evaluation of the WRF model output is presented using both surface and upper air observations. Evaluation of the HYSPLIT model is performed through a comparison of the vertical distribution of MPB observed in a previous study. A secondary HYSPLIT evaluation is performed using aerial surveys taken during the following summer (2006), which identify the previous years' beetleinfested regions. Beetle flight distances from the time of beetle emergence to the time of peak clear-air returns are calculated for each trajectory, and the distribution of all flight distances is presented. The mean back trajectory distance is 20.2 km with a standard deviation of 13.6 km. These values represent the MPB flight distance during half of the beetle atmospheric residence time, and typical daily windassisted dispersion distances would be expected to be roughly double this value. Mean beetle residence time in the atmosphere over the 10 emergence events is found to be 3.2 h.

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Evaluating indices of body condition in two cricket species

Kelly

Tawes

Worthington

2014

Ecology and Evolution

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Body mass components (dry mass, lean dry mass, water mass, fat mass) in each sex correlate strongly with body mass and pronotum length in Gryllus texensis and Acheta domesticus. Ordinary least squares (OLS) regression underestimates the scaling relationship between body mass and structural size (i.e., pronotum length) in both cricket species compared with standard major axis (SMA) regression. Standardized mass components correlate more strongly with scaled mass index () than with residual body mass (R i). R i represents the residuals from an OLS regression of log body mass against log pronotum length. Neither condition index predicts energy stores (i.e., fat content) in G. texensis. R i is not correlated with energy stores in A. domesticus whereas is negatively correlated. A comparison of condition index methods using published data showed that neither sex nor diet quality affected body condition at adulthood in G. texensis when using the scaled mass index. However, the residual index suggested that sex had a significant effect on body condition. Further, analysis of covariance (ANCOVA) suggested that diet quality significantly affects body mass while statistically controlling for body size (i.e., body condition). We conclude that the statistical assumptions of condition index methods must be met prior to use and urge caution when using methods that are based on least squares in the y -plane (i.e., residual index ANCOVA).

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Using Automated Flight Mills to Manipulate Fat Reserves in Douglas-fir Beetles (Coleoptera: Curculionidae)

Cited by 37 publications

References 35 publications

Condition-dependent tolerance of monoterpenes in an insect herbivore

Condition-dependent tolerance of monoterpenes in an insect herbivore

Investigation into mountain pine beetle above-canopy dispersion using weather radar and an atmospheric dispersion model

Evaluating indices of body condition in two cricket species

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