Augmentative biological control of whiteflies using transplants

Abstract

Field studies showed that transplants can be used to move parasitoids into fields of commercially grown cantaloupe, Cucumis melo (Cucurbitaceae), and augment parasitism of sweet potato whitefly, Bemisia tabaci biotype B (=Bemisia argentifolii) (Homoptera: Aleyrodidae). Methods were developed to inoculate cantaloupe seedlings with newly imported Eretmocerus spp. (Hymenoptera: Aphelinidae), then transfer plants into both organic and conventional fields of cantaloupe in the desert growing region of southeastern California. Several obstacles to inoculating ''banker plants'' with an adequate number of parasitized whiteflies were overcome and numbers of parasitoids per transplant increased. In 1999 the use of banker plants was compared to a standard hand-release method and a no-release control in a replicated study at an organic farm. Augmentation through releases of parasitoids increased parasitism over that in the norelease controls (p < 0.05). Banker plants increased the proportion of parasitized whiteflies more than the hand-release method (0.21 vs. 0.08). During a region-wide demonstration spring 2000, plots receiving banker plants significantly increased parasitism over paired control plots at seven commercial farms of cantaloupe. Parasitism in banker plant treated plots in 2000 was higher in organic fields (seasonal average ¼ 0.30) than conventional ones (seasonal average ¼ 0.06). Differences may be due to the use of imidacloprid, a systemic insecticide, in conventional fields for whitefly control. Over the 2-year study, however, releases of parasitoids did not consistently reduce densities of B. tabaci. Only in late season at some sites in 2000 were whitefly densities lower in release plots than paired controls. Most of the parasitoids recovered and identified from plots receiving parasitoids were the same as those released, Eretmocerus spp. (ex. Ethiopia M96076), and E. hayati (M95012, ex. Pakistan).

The Banker Plant Method in Biological Control

“…In a few cases, among the investigated systems (6% of systems listed in Tables 2-4), the plant species chosen as banker plant is the same as the crop species (Parr and Stacey, 1976;Stacey, 1977;Goolsby and Ciomperlik, 1999;Pickett et al, 2004;G. Murphy, pers.…”

“…While this was originally done as a refinement of the "pest-in-first"-strategy, in more recent cases, the choice was deliberate. This could be based on the expectation that by using the same variety as the crop, unpredicted effects of different varieties or plant species could be avoided (Goolsby and Ciomperlik, 1999;Pickett et al, 2004). Alternatively it could be a result of growers taking immediate advantage of in-house observations on differential attractiveness between varieties; for instance, by moving more susceptible varieties in among less susceptible varieties and using their more attractive qualities as the starting point for a banker plant system (G. Murphy, pers.…”

“…(e.g., Xu, 1991;Osborne et al, 1991) and Eretmocerus sp. (e.g., van der Linden and van Staij, 2001;Pickett et al, 2004) (Hymenoptera: Aphelinidae)] and of leafminers [Dacnusa sibirica Telenga (Hymenoptera: Braconidae) and Diglyphus isaea Walker (Hymenoptera: Eulophidae) (e.g., Goossens, 1992)]. …”

Biological Control, Functional Biodiversity and Ecosystem Services in Insect Pest Management

“…Banker plant systems are a technique of conservation biological control wherein a non-crop plant is deliberately infested with a non-pest herbivore as an alternate host for a parasitoid or predator of the target crop pest (Van Driesche et al 2008 ;Pickett et al 2004 ). A specifi c natural enemy may also be established on the banker plants to target a specifi c pest (Frank 2010 ) .…”

Mass Rearing Bemisia Parasitoids for Support of Classical and Augmentative Biological Control Programs

“…In this chapter, we describe several rearing techniques developed in support of augmentative biological control demonstration projects in California, Arizona, and Texas to establish new species of Eretmocerus and for greenhouse biological control evaluations in several states (Goolsby and Ciomperlik, 1999;Pickett et al, 2004;Goolsby et al, 2004). The species reared on Bemisia tabaci (Gennadius) Fifty-eight populations and/or species of parasitoids were reared at MBCL from 1991MBCL from to 1999.…”