Feeding and survival in parasitic wasps: sugar concentration and timing matter

Abstract

Siekmann, G., Tenhumberg, B. and Keller, M. A. 2001. Feeding and survival in parasitic wasps: sugar concentration and timing matter. -Oikos 95: 425-430.Sugar consumption can increase the longevity and lifetime fecundity of many species of parasitic wasps. Consequently, for these insects the availability of sugar sources in the field is important for their reproductive success. As sugar sources can be highly variable in quantity, space and time, the chances of finding a sufficient amount of sugar to increase longevity might be very low. Therefore, the reward from a single feeding event can be critical for the forager's fitness. We measured the longevity of the parasitoid Cotesia rubecula after a single honey meal differing in sugar concentration (25, 47, 86% w/w) and timing (day of emergence and 24 h later). Survival was analysed with Cox's Proportional Hazards Model. The risk of starving to death in sugar-fed wasps was reduced by 0 -73% in comparison to unfed wasps, depending on sugar concentration and timing. Longevity was significantly increased by sugar concentration and by feeding later in life. Our results suggest that in the field, adult C. rubecula has to locate food at least once per day to avoid starvation. Many species of parasitic wasps can increase their reproduction through feeding on supplemental sugar sources (Leius 1961a, b, Syme 1975, Chippendale 1978, England and Evans 1997, Heimpel et al. 1997a. Sugar feeding usually results in an increase in longevity that is often positively correlated with a higher fecundity (Wolcott 1942, Leius 1961b, Sahragard et al. 1991, Hagley and Barber 1992, Morales-Ramos et al. 1996, Heimpel et al. 1997a. Successful sugar foraging is considered to be a critical factor that influences the lifetime reproduction of parasitic wasps in the field (Wäckers and Swaans 1993, Sirot and Bernstein 1996, England and Evans 1997, Jacob and Evans 1998, Heimpel et al. 1998), but little has been done on the estimation of realistic lifetimes of sugar-feeding wasps when sugar is not constantly and easily available. In many habitats foods and hosts of parasitic wasps are spatially separated or not available at the same time, resulting in rare food encounters. G. Siekmann, B. Tenhumberg and M. A. Keller, Dept of Applied andTaking into account the spatial and temporal variability of sugar sources in the field we address the specific question of how much a single sugar meal affects survival in adult Cotesia rubecula (Marshall) (Hymenoptera: Braconidae). The estimation of longevity and reproduction of parasitic wasps in the field should not rely on data obtained from cage experiments with ad libitum sugar conditions. Considering the different qualitative, spatial and temporal scales at which sugar sources occur in the field (Jervis et al. 1993), this would lead to a drastic overestimation of the lifetime reproduction of wasps. The quantity and quality of sugar sources in the field vary as they can be obtained from various sources such as floral and extrafloral nectar, other plant materials ...

An acquired distaste: Sugar discrimination by the larval parasitoidMicroplitis croceipes(Hymenoptera: Braconidae) is affected by prior sugar exposure

“…However, feeding time on a sugar solution may not always reflect consumption of the solution because of different feeding speeds due to different viscosities of the sugars (Siekmann et al, 2001;Wäckers, 2001;Wäckers et al, 2006;Faria et al, 2008;Wyckhuys et al, 2008). In the present study, we found positive linear relationships between feeding time and consumption for 1 mol l −1 in all four sugars, suggesting that at this concentration, feeding time is a good indicator of gustatory responses and consumption in all sugars tested.…”

“…This suggests that feeding speed is lower for maltose solutions than for the other sugar solutions. Siekmann et al (Siekmann et al, 2001) and Wyckhuys et al (Wyckhuys et al, 2008) suggest that the higher viscosity of maltose may reduce feeding speed relative to the other sugars, but Nithiyanantham and Palaniappan (Nithiyanantham and Palaniappan, 2013) and Chirife and Buera (Chirife and Buera, 1997) …”

Nutritional value of floral nectar sources for flight in the parasitoid wasp, Cotesia glomerata

“…Previous laboratory studies show that adult parasitoids deprived of access to nectar or sugar sources have a reduced longevity and/or fecundity (Jacob & Evans, 2000;Schmale et al, 2001;Siekmann et al, 2001). The energy obtained through adult feeding on supplemental sugar sources may also be necessary for sustaining flight capacity in parasitoids because flight in insects is a highly energy-demanding behaviour with metabolic rates during flight increasing 50-100-fold compared with metabolism at rest (Beenakkers et al, 1984;Hoferer et al, 2000).…”

“…In the field, adult parasitoids are observed visiting flowering plants to feed on floral or extrafloral nectar (Jervis et al, 1993;Idris & Grafius, 1995), and crops with nearby flowering vegetation have higher parasitism rates (Landis & Hass, 1992;Zhao et al, 1992;Stephens et al, 1998), although the finding of a recent field study suggests that vegetative characteristics of floral resource plants rather than flowers might influence the abundance of natural enemies (Rebek et al, 2005). In the laboratory, plant nectar shows a higher nutritional value compared with honeydew for sustaining longevity and fecundity in hymenopteran parasitoids (McDougall & Mills, 1997;Wa¨ckers, 2002;Lee et al, 2004).Previous laboratory studies show that adult parasitoids deprived of access to nectar or sugar sources have a reduced longevity and/or fecundity (Jacob & Evans, 2000;Schmale et al, 2001;Siekmann et al, 2001). The energy obtained through adult feeding on supplemental sugar sources may also be necessary for sustaining flight capacity in parasitoids because flight in insects is a highly energy-demanding behaviour with metabolic rates during flight increasing 50-100-fold compared with metabolism at rest (Beenakkers et al, 1984;Hoferer et al, 2000).…”

Role of vitamins on various biological aspects of an egg parasitoid, Trichogramma chilonis (Ishii) (Hymanoptera: Trichogrammatidae) on its laboratory host, Corcyra cephalonica

“…Sugar feeding has been reported to increase parasitoids longevity (Wäckers, 2001; Siekmann et al, 2001) as well as its fecundity (Schmale et al, 2001). In addition, well fed parasitoids are usually more active and more focused in seeking out their herbivores hosts (Wäckers, 1994).…”