Effect of Bemisia tabaci honeydew and its carbohydrates on search time and parasitization of Encarsia bimaculata

Abstract

The search time of Encarsia bimaculata Heraty et Polaszek was examined and recorded by using filter paper discs in Petri dish arenas impregnated with Bemisia tabaci (Gennadius) honeydew or its component carbohydrates. Our data show that E. bimaculata used honeydew as a contact kairomone to locate its host. Females responded quantitatively to the honeydew and the search time in the treated patches increased. This increase was concentrationdependent with regard to the amount of honeydew applied, but it levelled off 0.05 g/ml onwards. The response of E. bimaculata to honeydew decreased with increasing time after application and was significantly reduced 8 days after treatment. The parasitoid females were also arrested in patches treated with glucose, fructose, trehalulose and trehalose; trehalose elicited the highest response in the parasitoids. However, sucrose and low concentrations of melezitose did not elicit a significant effect. Glucose, sucrose, fructose, trehalose and trehalulose increased the longevity of the parasitoid females by a factor of 8.4, 8.1, 6.3, 6.1 and 4.2, respectively. Melezitose and 0.15 g/ml natural honeydew, however, had no effect on parasitoid lifespan. The effects of aqueous spray of honeydew sugars on egg to adult survivorship and parasitization of B. tabaci by E. bimaculata significantly differed when compared with controls only in cases where mixtures of glucose + fructose and trehalose and fructose + trehalose were applied.

Effects of sugars on the longevity of adult females of Eretmocerus eremicus and Encarsia formosa (Hymenoptera: Aphelinidae), parasitoids of Bemisia tabaci and Trialeurodes vaporariorum (Hemiptera: Alyerodidae), as related to their honeydew feeding and host feeding

“…nr. furuhashii than glucose or sucrose (Mandour et al, 2005(Mandour et al, , 2007, differing from the results obtained from En. formosa, En.…”

“…In B. curculionis, there was no significant difference in longevity between trehalose-fed and sucrose-fed females, but glucose and fructose alone appeared to have the most benefits while trehalose was not as useful for increasing parasitoid longevity (Jacob and Evans, 2004). In addition, Mandour et al (2007) showed that trehalose had a significantly lower effect on female longevity of En. bimaculata than glucose and sucrose, but almost the same effect as fructose, and Mandour et al (2005) reported a similar result for Er.…”

“…Since adult females of parasitoids attacking honeydew-producing insects have easy access to honeydew, these adults may be more dependent on the use of host-honeydew sugars than parasitoids attacking insects that do not produce honeydew. Quite recently, the effects of honeydew sugars on female longevity of parasitoids attacking honeydew-producing insects, such as aphids and whiteflies, have been reported by Hogervorst et al (2007), Mandour et al (2005Mandour et al ( , 2007 and Hardin et al (2008).…”

“…The exception is the study by Giron et al (2002) who injected sugars into the hemolymph of Eupelmus vuilletti (Crowford). Mandour et al (2005Mandour et al ( , 2007 determined the effect of trehalose on the female longevity of host-feeding parasitoids Eretmocerus sp. nr.…”

Delayed development of the whitefly (Bemisia tabaci) and increased parasitism by Encarsia bimaculata in response to sublethal doses of piperonyl butoxide

“…The B. tabaci population used in this study was originally collected from hibiscus plants grown in the horticultural unit of South China Agricultural University (SCAU). Whiteflies ( B. tabaci ) and parasitoids ( E. bimaculata ) were reared following the methods of Qiu et al (2007a, b) and Mandour et al (2006, 2007a, b). Colonies were maintained on hibiscus plants housed in rearing cages (60 × 60 × 60 cm) in the laboratory for at least 10 generations before used in experiments.…”