Performance of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) on eggs of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a polyphagous pest with a wide geographic distribution. This pest first arrived in Brazil in 2013, and since then studies on possible control methods for it have been necessary. A possible method for the control of H. armigera is using the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Therefore, the objective of this study was to evaluate the performance of T. pretiosum on H. armigera eggs, which are known to represent suitable hosts for the development of this parasitoid species in the laboratory. Parasitism and emergence rates and the duration of the egg-to-adult period of T. pretiosum were investigated following 24- and 48-h exposures of this parasitoid to H. armigera and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) eggs. The longevity of offspring after the 24-h exposure was studied, as well as the frequency of parasitism and emergence, host preference, and the emergence of offspring from eggs of different ages or oviposited by lepidopterans on different days. Parasitism was 14.4 and 34.9% more frequent on C. cephalonica than on H. armigera after 24 and 48 h of exposure, respectively. In C. cephalonica, parasitism was 27.2% higher after 48 h. Parasitism was more frequent on C. cephalonica eggs collected on the second day of oviposition (76.2%), and on H. armigera on the third day of oviposition (71.1%). Parasitism frequency was lower on 2-day-old C. cephalonica eggs (63.3%) and on 3-day-old H. armigera eggs (41.3%). When tested with a chance of choice between hosts, T. pretiosum preferred H. armigera, while in the test with no chance of choice there was no difference in preference. Thus, T. pretiosum may be considered a tool for the Integrated Pest Management (IPM) of H. armigera.

Laboratory and field studies supporting augmentation biological control of oriental fruit moth, Grapholita molesta (Lepidoptera: Tortricidae), using Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae)

“…2(B)), and parasitism success was significantly reduced in eggs of this age. For this reason, mass production of Trichogramma typically utilizes host eggs pretreated with ultraviolet (UV) irradiation to arrest their development in an early stage before they are provided to wasps for oviposition 14,42 . Thus, the efficacy of field releases will be maximized by releasing Trichogramma dendrolimi early in the oviposition cycle of G. molesta in pear orchards.…”

“…In order to prevent mutual interference among wasps, a single female wasp was introduced in each dish and allowed to parasitize host eggs for 24 h, with a 10% honey solution provided on a cotton ball. After female removal, the eggs were incubated under the same physical conditions as the wasp colony and parasitism was assessed daily by counting the number of darkened eggs; emergence success was tallied as the number of darkened eggs with emergence holes 14 . Five replicates were conducted for each host egg density with each Trichogramma species.…”

“…Egg parasitoids in the genus Trichogramma develop within the eggs of various insects, are amenable to mass‐rearing, and have been successfully employed in many agricultural contexts, especially against boring pests as it is difficult to control the larvae in their concealed feeding sites 8–14 . Egg parasitoids oviposit in host eggs, hijack the hosts' physiology to support their own development, and ultimately kill the host 15 .…”

“…Egg parasitoids oviposit in host eggs, hijack the hosts' physiology to support their own development, and ultimately kill the host 15 . Several Trichogramma species egg parasitoids have been successfully used against Lepidopteran pests of crops by inundative application, particularly in borer pest control 8–14 . In China, both Trichogramma dendrolimi and Trichogramma chilonis have been augmented against G. molesta in pear orchards, 16 but their relative efficacy against this pest has not been directly compared.…”

A review on biological interactions and management of the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

“…In laboratory conditions, the maximum parasitism level in H. armigera eggs was around 50%, indicating that the potential of T. pretiosum as a biological control agent should be paired with other methods for effective management, such as biological and/or chemical insecticides. Needless to mention, the chemical insecticides must be selective and harmless to these natural enemies (Laurentis et al., 2019).…”