Effect of Host Change on Demographic Fitness of the Parasitoid,Trichogramma brassicae

Abstract

Trichogramma brassicae (Bezdenko) is the most important species of Trichogramma parasitoids in Iran. The cotton bollworm, Helicoverpa armigera (Hubner) is a polyphagous insect pest that attacks many crops including cotton, maize, soybean, tomato, etc. The bollworm egg is a suitable target for many Trichogramma species. Factitious hosts such as eggs of the flour moth, Anagasta kuehniella (Zeller) and cereal moth, Sitotroga cerealella (Hubner) are used for mass rearing purposes. But a problem that arises sometimes in laboratory cultures is the development of a tendency toward laboratory hosts following a few generations rearing with them. This may tend to a low efficiency on target pest in field conditions. In this study the possibility of declining efficiency of the parasitoid on target pest by developing such a preference to alternative hosts in previous generations were investigated when the flour moth or cereal moth uses as laboratory host. Two generations of T. brassicae were reared on each of the mentioned hosts and then transferred to H. armigera eggs for two further generations. The intrinsic rate of natural increase as well as other life table parameters were used for monitoring fitness of the parasitoid at successive generations. Even generations were included to determine if previously rearing host affected parasitoid performance. Results revealed that host shift from cereal moth to bollworm caused a sudden fall in population growth parameters (both intrinsic rate of natural increase and net replacement rate). Further rearing on bollworm eggs led to a relapse in both parameters. No similar effect was observed in cultures initiated with the flour moth. As a whole, cereal moth was a more suitable host than flour moth.

Best Host Age of Anastrepha obliqua (Diptera: Tephritidae) for Multiplication of Four Native Parasitoids from the Americas

“…Although it is known that host preference by parasitoid species is defined genetically ( Singer et al 1992 ), under a mass rearing situation, different intraspecific interactions (i.e., extrinsic and intrinsic competition) may occur and influence the results and quality of the produced parasitoids ( Canale and Benelli 2012 , Queiroz et al 2017 ). For this reason, under this scenario the host preference by parasitoid species must be properly analyzed, looking for those ages that better render higher levels of parasitism, adult emergence, and a female biased sex ratio ( Li et al 2006 , Iranipour et al 2010 ).…”

Suitability assessment of three Trichogramma species in the control of Mythimna separata (Lepidoptera: Noctuidae)

“…In addition, the effect of host change on fitness of Trichogramma also should be considered (van Bergeijk, Bigler, Kaashoek, & Pak, 1989;El-Wakeil, 2007;Iranipour, Vaez, Ghanbalani, Zakaria, & Jafarloo, 2010).…”

Trichogramma brassicae, Trichogramma cacoecia ve Trichogramma evanescens’ in konukçu ve yumurta yaşı tercihi üzerinde araştırmalar

“…Greenberg et al (1998), Trichogramma türlerinin vücut büyüklüğü ile parazitoit doğurganlığının yetiştirildiği konukçu yumurtasına bağlı olduğunu ve T. maidis üretiminde, E. kuehniella ile S. cerealella yumurtaları kullanıldığında aralarında önemli bir farklılığın bulunmadığını bildirmişlerdir. Iranipour et al (2010), konukçu değişikliğinin parazitoitlerin performansını düşürdüğünü, S. cerealella üzerinde yetiştirilen parazitoitlerde parazitoit performansının belirgin olarak düşüğünü bildirmişlerdir.…”