Life table assay of field‐caught Mediterranean fruit flies, Ceratitis capitata, reveals age bias

Abstract

Though traps are used widely to sample phytophagous insects for research or management purposes, and recently in aging research, possible bias stemming from differential response of individuals of various ages to traps has never been examined. In this paper, we tested the response of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) males and females of four ages (spanning from 1 to 40 days) to McPhail-type traps baited with a synthetic food attractant in field cages and found that the probability of trapping was significantly influenced by age. The type of food on which flies were maintained before testing (sugar or protein) also had a strong effect and interacted with age. In another experiment, we collected wild C. capitata adults of unknown age using 1–3 methods and then reared them in the laboratory until death. The survival schedules of these flies were subsequently used in a life table assay to infer their age at the time of capture. Results showed that on a single sampling date, males captured in traps baited with a food attractant were younger compared with males aspirated from fruiting host trees, or males captured in traps baited with a sex attractant. Likewise, females captured in food-baited traps were younger compared with aspirated females. In addition to providing the first evidence of age-dependent sampling bias for a phytophagous insect species, this paper also provides a novel approach to estimate the differences in the age composition of samples collected with different techniques. These findings are of utmost importance for several categories of insects, medically important groups notwithstanding.

Seasonality of Post-capture Longevity in a Medically-Important Mosquito (Culex pipiens)

“…For small cost, minimal effort and simple technology requirements, monitoring regional patterns in longevity potential of live-caught mosquitoes as in this study have the potential to provide insights into trends in the age structure of mosquito populations and their vectorial capacity. These include trends in population age, population pulses as inferred from the sudden appearance of long-lived mosquito subgroups, age shifts both pre-and post-intervention, and comparison of age bias in sampling (see Kouloussis et al, 2009).…”

Trapping and the Detection, Control, and Regulation of Tephritid Fruit Flies

“…The authors noted that this technique would be further improved by development of female-specific lures that would reduce the number of sterile males that could enter the trap and mate with wild females. Live trapping of fruit flies could also be used to determine the age structure and reproductive potential of a pest population (Kouloussis et al 2009(Kouloussis et al , 2011. Traps baited with 3C BioLure were also used to obtain wild C. capitata for use in release/recapture studies to determine effective sampling range ).…”

“…Historically, lures related to feeding behavior have been based on protein volatiles to attract females of different fruit fly species (López and Hernández-Becerril 1967;Houston 1981;Malo 1992;Thomas et al 2001;Kouloussis et al 2009;Díaz-Fleischer et al 2009, Epsky et al, Chap. 3, this volume).…”

“…In the Mexican fruit fly, Anastrepha ludens (Loew), for example, flies less than 4 days old prefer sugar over protein, while 5-9 day-old flies respond to protein and sugar equally . Thus, trapping programs encounter a variable mosaic of fly physiological states, with certain lures and traps likely biased to capture only a subset of the population (Thomas et al 2001;Kouloussis et al 2009). …”

Graphical and demographic synopsis of the captive cohort method for estimating population age structure in the wild

“…Therefore with certain simplifying assumptions the former can be estimated from the latter using demographic models and reference life tables. Publications subsequent to the Müller et al paper (Müller et al, 2004) extended the theoretical foundations for the captive cohort method (Müller et al, 2007; Vaupel, 2009), estimated the age structure in a wild medfly population (Carey, 2011; Carey et al, 2008), explored the implications of post-capture patterns of reproduction (Kouloussis et al, 2011) and age bias in sampling (Kouloussis et al, 2009), and modified the concept to estimate the shifts in mean age (Carey et al, 2012). …”