Interaction Between Bt-Transgenic Cotton and the Whitefly’s Parasitoid, Encarsia Formosa (Hymenoptera: Aphelinidae)

Abstract

Transgenic Bt cotton developed against lepidopteran pests may not be compatible with parasitoid of secondary pests such as Bemisia tabaci which attack many plants such as cotton. In this study, the effects of Bt cotton on the demographic parameters of Encarsia formosa, parasitoid of B. tabaci were assessed. The data were analysed using the age specific, two-sex life table parameters. The results indicated that pre-adult developmental time, the total preoviposition period (TPOP) and the adult preoviposition period (APOP) in the Bt cotton were significantly longer than in the non-Bt cotton. Also, fecundity and body size in both lines were significantly different. The fecundity was 23.64±0.73 and 43.75±0.89 eggs/females in the Bt and non-Bt cotton, respectively. All the population parameters were affected by the Bt cotton. The intrinsic rate of increase (r) was 0.15 day-1 in the non-Bt cotton but it was 0.10 day-1 in the Bt cotton. The finite rate of increase (λ) was 1.11 day-1 in the non-Bt cotton whilst it was 1.08 in the Bt cotton. The net reproductive rate (R0) in the non-Bt cotton was 36.75 but in the Bt cotton these parameters showed 19.62 offspring/individual. Also, the mean generation time (T ) in the non-Bt and Bt cotton was 22.69 and 27.79 days, respectively. The results illustrated, that although transgenic crops are effective tools for management of the target pests, they can adversely affect, either directly or indirectly, the natural enemies dependent on these plants.

Development and parasitism of Encarsia hispida (Hymenoptera: Aphelinidae) on Bemisia tabaci biotype B in cotton

“…The values corresponding to the periods egg to larva and pre-imago of this study differ from those found by Azimi et al (2014) for Encarsia formosa, and Pessoa et al (2016) for Encarsia desantisi (Hymenoptera: Aphelinidae) in non-BT cotton. Thus, researchers have shown that species from the genus Encarsia may reduce or extend its life cycle in function of the host plant where the whitefly developed.…”

Potensi Tanaman Transgenik Sebagai Salah Satu Teknologi Dalam Pengelolaan Hama Terpadu

“…Pengaruh langsung dari tanaman transgenik apabila musuh alami memakan nektar dari tanaman transgenik. Sedangkan pengaruh tidak langsung dari tanaman transgenik apabila musuh alami memparasit atau memakan hama yang hidup pada tanaman transgenik (Arpaia et al dalam Azimi et al, 2014). Parasitoid Encarsia formosa tumbuh lambat pada kapas Bt, sehingga pertumbuhan dan perkembangannya lebih lambat dibandingkan parasitoid pada kapas non Bt (Azimi et al, 2014).…”

“…Sedangkan pengaruh tidak langsung dari tanaman transgenik apabila musuh alami memparasit atau memakan hama yang hidup pada tanaman transgenik (Arpaia et al dalam Azimi et al, 2014). Parasitoid Encarsia formosa tumbuh lambat pada kapas Bt, sehingga pertumbuhan dan perkembangannya lebih lambat dibandingkan parasitoid pada kapas non Bt (Azimi et al, 2014). Pada kajian yang dilakukan selama 4 tahun di lima lokasi di Wisconsin, diperoleh data bahwa populasi predator rata-rata 63,8% lebih rendah di lahan-lahan yang ditanami kentang non-Bt yang pengendalian hamanya dengan menggunakan pestisida dibanding dengan lahan-lahan yang ditanami kentang Bt transgenik, sedangkan pada lahan-lahan yang disemprot pestisida 58,4% lebih rendah dibandingkan dengan populasi parasitoid di areal pertanaman transgenik Bt (Hoy et al, 1998).…”

“…Musuh alami merupakan serangga yang tidak satu jenis dengan hama sasaran, sehingga kemungkinan toksin Bt yang ada pada tanaman transgenik tidak berpengaruh negatif terhadap musuh alami. Penanaman tanaman transgenik akan mengurangi penggunaan insektisida, baik yang sintetik ataupun yang organik (Azimi et al, 2014). Musuh alami, baik itu predator maupun parasitoid biasanya lebih retan terhadap insektisida dibandingkan dengan hama target.…”

Identification and selection of resistance to Bemisia tabaci among 550 cotton genotypes in the field and greenhouse experiments

“…Some studies also reported that Bt-cotton plants provide substantial economic benefits and reduce the use of harmful insecticides [6,7] . The secondary pests such as aphids, mirid bugs and whiteflies are not susceptible to Bt-cotton plants and they directly benefit from reduced application of chemical insecticides [8][9][10][11][12] . Specifically, the mirid bugs (Heteroptera: Miridae) have shown tendency to produce outbreaks and were suggested to be considered as a primary target for development forecasting and management strategies in Btcotton fields in China [13][14][15] .…”