Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Abstract

Biotypes of Trichogramma auslralicum were reared on artificial diet "A", Helicoverpa armigera (Hiibner) (natural host) eggs and Sifofroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. ausfralicum reared in vifro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H . armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.

Biological characters of Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) reared in vitro versus in vivo for thirty generations

“…Thus, parasitoids reared on artificial medium appeared to be inferior compared with those reared on A. pernyi eggs. The emergence rates of both T. dendrolimi and Trichogramma chilonis reared in vitro were 90% of that reared in vivo 18 , and in vitro –reared females of Trichogramma australicum produced significantly more progeny than did females reared on natural or factitious hosts for only one generation 9 . Trichogramma minutum were reared for 10 generations on an artificial diet that resulted in more deformed females, but also in adults that lived longer, parasitized more Helicoverpa zea eggs and had similar emergence rates compared with insects reared in vivo on H. zea eggs, suggesting, while this medium is nutritionally adequate, additional work is required for it to be suitable for use in mass rearing programs 8 .…”

“…In the case of Trichogramma , Cônsoli & Parra showed that females reared on artificial diets have a reduced fecundity compared with those reared on natural hosts 7 , whereas others have reported similar fecundity and longevity between females reared in vivo and in vitro 8,9 . Thus, the emergence rate, sex ratio, fecundity, and longevity are used as reproduction parameters for controling the quality of artifically reared Trichogramma 10,11 .…”

“…Most studies examining the effects of rearing parasitoids on artificial host eggs versus artificial and/or natural hosts only consider the effects on a single generation 6,9,12,13 , with few examining the effects of continuous culture for several generations 8,14–16 . Meanwhile, even fewer studies have investigated the quality of the insects produced using artificial media by comparing not only biological characters, but also biochemical parameters over multiple generations 6,13 .…”

Development of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) in fertile and infertile Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) eggs

“…australicum wasps produced from Helicoverpa armigera (Hübner) eggs is superior to wasps produced from S . cerealella eggs (Nurindah et al 1997). Our mass‐rearing program for laboratory experiments of Trichogramma australicum Girault, therefore, uses eggs of H. armigera .…”

“…In Australia, eggs of S. cerealella are commonly used to mass produce Trichogramma in laboratories (Twine & Lloyd 1982;Scholz & Murray 1995) and insectaries (Seymour 1994). However, the reproductive performance of T. australicum wasps produced from Helicoverpa armigera (HuÈ bner) eggs is superior to wasps produced from S. cerealella eggs (Nurindah et al 1997). Our mass-rearing program for laboratory experiments of Trichogramma australicum Girault, therefore, uses eggs of H. armigera.…”