the side-effects of amitraz, buprofezin and propargite were studied on encarsia formosa (gahan)in the laboratory, using a life table response experiment and the iobc system for their toxicity. bioassayswere conducted by dipping bean leaves containing third instar nymphs of the whitefly trialeurodesvaporariorum (westwood), parasitized by e. formosa, in insecticide solutions or caging adult paras...

Plants attacked by herbivorous insects emit volatile compounds that attract predators or parasitoids of the herbivores. Plant fitness increases when these herbivorous insects are parasitized by solitary parasitoids, but whether gregarious koinobiont parasitoids also confer a benefit to plant fitness has been disputed. We investigated the relationship between parasitoid load of the gregarious Co...

Discrete-time models are the traditional approach for capturing population dynamics of a hostparasitoid system. Recent work has introduced a semi-discrete framework for obtaining model update functions that connect host-parasitoid population levels from year-to-year. In particular, this framework uses differential equations to describe the hosts-parasitoid interaction during the time of year wh...

In North America, the sweetpotato whitefly, Bemisia tabaci Genn., is an important pest of greenhouse poinsettia. Growers have limited options to control this pest during propagation of cuttings, which are rooted under mist for several weeks. Early establishment of this pest increases the difficulty of managing the whitefly and retaining high aesthetic standard during the remaining crop producti...

The sweetpotato whitefly, Bemisia tabaci Genn., has been present in Arizona since the first cultivation of cotton in the 1920s (Russell 1975). For much of its history, its importance was as a sporadic pest and vector of cotton leaf crumple virus. Meanwhile around the world, outbreaks of whiteflies were recorded in cotton in places like the Sudan, Punjab of India, and Israel. The New World also ...

The abundance and distribution of insect herbivores is determined by, among other things, plant quality and natural enemies. These two factors vary temporally and spatially, subsequently affecting seasonal population dynamics. The relative influence of plant quality and natural enemies on the seasonal dynamics of Bemisia tabaci (Gennadius) was investigated in a 3-yr field study in cotton. Plant...

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and host-use efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susce...

Understanding the dynamics of potential inter- and intraspecific competition in parasitoid communities is crucial in the screening of efficient parasitoid species and for utilization of the best parasitoid species combinations. In this respect, the host-parasitoid systems, Bemisia tabaci and two parasitoids, Eretmocerus hayati (exotic) and Encarsia sophia (existing) were studied under laborator...

We investigate the effect of parasitoid phenology on host-parasitoid population cycles. Recent experimental research has shown that parasitized hosts can continue to interact with their unparasitized counterparts through competition. Parasitoid phenology, in particular the timing of emergence from the host, determines the duration of this competition. We construct a discrete-time host-parasitoi...