Eretmocerus warrae prefer to attack mid-aged hosts to gain fitness for both adults and their offspring

Insight into the success of whitefly biological control using parasitoids: evidence from theEretmocerus warrae−Trialeurodes vaporariorumsystem

“…The parasitoids were allowed to stay in the Petri dish for 24 h, after which time they were removed. Host feeding was determined by observation of body fluid effused as a result of penetration of the female ovipositor into the vasiform orifice of host nymphs under a stereomicroscope (Leica MZ12, Germany). All experimental parasitoids were used only once.…”

“…Therefore, both host feeding and parasitization by E. warrae contribute to whitefly mortality. At a consistent host and parasitoid density, E. warrae wasps prefer to attack mid‐aged hosts and allocate about 20% of these hosts for feeding and the rest for parasitization . However, in the natural environment the density of both hosts and parasitoids is variable in space and time.…”

“…At a consistent host and parasitoid density, E. warrae wasps prefer to attack mid-aged hosts and allocate about 20% of these hosts for feeding and the rest for parasitization. 20 However, in the natural environment the density of both hosts and parasitoids is variable in space and time. Prior to the present study, nothing was known about how the dynamic density of both E. warrae and greenhouse whitefly affected the three key parasitoid fitness parameters (TKPFP), host searching, host feeding and parasitization, knowledge of which is essential for the development of a cost-effective greenhouse whitefly biological control programme using E. warrae.…”

“…Among the six Eretmocerus species that have been reared from T. vaporariorum , E. warrae Naumann and Schmidt (Hymenoptera: Aphelinidae) is a thelytokous (no males) and specialist parasitoid . Like other Eretmocerus species, E. warrae insert their ovipositors and lay eggs between the whitefly nymphs and the leaf surface, eggs hatch under the hosts, and the first instar larvae penetrate the hosts when the latter reach the fourth instar . Furthermore, as with other congeneric species, E. warrae is a pro‐synovigenic parasitoid where adults feed on hosts for egg production and somatic maintenance, and the wasp does not lay eggs under hosts that have been subject to feeding activity and thus killed (AH, personal observation).…”

“…Like other Eretmocerus species, E. warrae insert their ovipositors and lay eggs between the whitefly nymphs and the leaf surface, eggs hatch under the hosts, and the first instar larvae penetrate the hosts when the latter reach the fourth instar . Furthermore, as with other congeneric species, E. warrae is a pro‐synovigenic parasitoid where adults feed on hosts for egg production and somatic maintenance, and the wasp does not lay eggs under hosts that have been subject to feeding activity and thus killed (AH, personal observation). Therefore, both host feeding and parasitization by E. warrae contribute to whitefly mortality.…”