Synthetic Herbivore-induced Plant Volatiles Increase Field Captures of Parasitic Wasps

Abstract

Field evidence for attraction of parasitic wasps from the families Encyrtidae and Mymaridae to grapevines baited with synthetic versions of three herbivore-induced plant volatiles (HIPV) is presented. In a replicated experiment conducted in a juice grape vineyard, sticky cards in blocks baited with controlled-release dispensers of methyl salicylate (MeSA), methyl jasmonate (MeJA) or (Z)-3-hexenyl acetate (HA), trapped significantly greater numbers of Metaphycus sp. (Encyrtidae) than cards in unbaited blocks during MayÀSeptember. Significantly greater numbers of Anagrus spp. (Mymaridae) were trapped in MeSA and MeJA-baited blocks than in unbaited blocks, during AugustÀSeptember. Greater numbers were recorded in HA-baited blocks in September only. Previous studies showed Encyrtidae and Anagrus spp. were not attracted to sticky cards baited with vials of MeSA, MeJA or HA. Possible reasons for attraction in this study are discussed including the possibility that synthetic, gaseous HIPV from controlled-release dispensers may stimulate plants to produce natural blends of parasitoid-attracting volatiles.

Potential for the Use of Exogenous Chemical Elicitors in Disease and Insect Pest Management of Conifer Seedling Production

“…Ibrahim et al [45] found that in Y-tube olfactometer tests with Cotesia vestalis the parasitoid of crucifer-feeding diamond back moth preferred odour of MeJA to filtered air. When released from traps MeJA and MeSA attracted parasitoids of the families Encyrtidae and Mymaridae to grapevines [46]. These observations indirectly suggest that MeJA treatment could have potential in attracting natural enemies of conifer seedling pests to intact plants if seedlings are treated before attack by pest insects and mites.…”

EAG-Active Herbivore-Induced Plant Volatiles Modify Behavioral Responses and Host Attack by An Egg Parasitoid

“…In particular, these studies showed that (Z)-3-hexenyl acetate, farnesene, and methyl salicylate could be used to manipulate behavior of beneficial insects under field conditions. These three compounds were attractive to numerous predators and parasitoids; methyl salicylate attracted the broadest diversity of insects and farnesene the least (James 2005;James and Grasswitz 2005). However, all compounds attracted the mymarid Anagrus daanei and other Anagrus species, although this effect was inconsistent.…”

“…Thaler (1999) also reported increases in parasitism of S. exigua on induced plants versus controls. A series of field studies demonstrated that sachets of individual synthetic HIPVs could be used to attract and retain natural enemies in perennial crop systems (James 2003a,b;James and Price 2004;James and Grasswitz 2005). In particular, these studies showed that (Z)-3-hexenyl acetate, farnesene, and methyl salicylate could be used to manipulate behavior of beneficial insects under field conditions.…”

“…These compounds were chosen because of our previous olfactometry results and previous studies on HIPVs with another mymarid (James 2005;James and Grasswitz 2005). Each plot was approximately 0.04 ha (20×20 m).…”

“…Exploitation of chemical signaling by plants that attract natural enemies has potential for enhancing biological control in agroecosystems (Hunter 2002). For example, synthetic herbivore-induced plant volatiles (HIPVs) have been used to attract and retain beneficial insects into vineyards and hopyards (James 2003a(James ,b, 2005, which has led to a reduction in pest densities (James and Price 2004;James and Grasswitz 2005). To date, however, little is known about practical application of HIPVs in cotton agroecosystems.…”