j. p. michaud

Using Ephestia kuehniella larvae as hosts, invert emulsion (IE) and an aqueous suspension (AS) of Beauveria bassiana (isolate IR34-JS2) and Metarhizium anisopliae (isolate IR41-TT1) formulations were compared when stored for three months at either 3 °C or 25 °C. Initially, IE formulations of isolates JS2 and TT1 were 13- and 14-fold more virulent than AS formulations, based on their LC50 values. JS2 LC50 values increased 1.3- and 5.6-fold for the AS and IE formulations, respectively, after 3 months storage at 3 °C, and 1.6 and 7.3-fold after 3 months at 25 °C, whereas values for TT1 increased 2.1- and 6.8-fold for these formulations at 3 °C, and 3.9- and 15.7-fold at 25 °C. Formulation and storage temperature interacted significantly to affect conidial production post-storage. Vegetative growth, conidiogenesis, and conidial germination of both isolates were better preserved at 3 °C than at 25 °C in vitro. The IE formulation preserved vegetative growth capacity better than the AS formulation at both temperatures, and better preserved conidiogenesis at 3 °C, a temperature that also improved TT1 conidial germination in the IE formulation. At 3 °C, the IE formulation yielded a relative speed of kill that was 3.5- and 1.3-fold faster for the JS2 and TT1 isolates, respectively, than the AS formulation. It can be concluded that IE formulations were superior to AS formulations, and that storage at 3 °C will help preserve the biological activity and pathogenicity of these fungi.

The Tomato Leaf Miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a cosmopolitan tomato pest that has driven a renewed reliance on pesticides in tomato production, negatively affecting biological control of other pests and creating environmental and health hazards. We tested five locally important Iranian tomato cultivars (TD, Karon, Petoprid, Matin, and 8320) for constituitive resistance to TLM by comparing its biological performance and life table parameters under standardized laboratory conditions (27.5±1°C, 65±5% RH, 16 L:8 D hours photoperiod). Survival and developmental rates of immature stages varied significantly among cultivars, as did female fecundity and main parameters of the life table. Karon was most suceptible, affording 90% juvenile TLM survival, the fastest development, and the highest female fecundity, with cultivar 8320 not significantly different in these regards. By contrast, Matin ranked most resistant; i.e. only 59% of larvae survived, and female fecundity was almost halved. TD was the next most resistant, being not significantly different from Matin in these metrics. The intrinsic rates of increase (r), in descending order, were Karon (0.178), 8320 (0.169), TD (0.146), Petoprid (0.138), and Matin (0.111). Matin and TD had the highest densities of glandular trichomes on adaxial leaf surfaces. These findings indicate that the Matin, Petoprid and TD are more resistant than the other cultivars and have potential as one component of an IPM strategy to manage T. absoluta.

The parasitoid wasp Trichogramma brassicae is one of the most important natural enemies used to biologically inhibit the egg stage of pests. Rearing of this parasitoid on different hosts and its interaction with entomopathogenic fungi Metarhizium anisopliae is very important in pest control. Therefore, this entomopathogenic fungus along with trichogramma parasitoid can be used in integrated pest management. In this study, effect of M. anisopliae (isolate M14) concentrations on parasitized eggs of Ephestia kuehniella and Sitotroga cerealella, oviposition preference and hatching percentage on the hosts, also, oviposition preference by parasitoid on E. kuehniella and S. cerealella eggs impregnated with different concentrations of M. anisopliae (isolate M14) and control treatment were studied. Probit analysis obtained from the effect of M. anisopliae (isolate M14) concentrations on E. kuehniella and S. cerealella eggs containing parasitoid showed the highest mortality of parasitoid on E. kuehniella. In the host preference test by choice and non-choice methods, the highest number of parasitic eggs and parasitoid hatching were recorded in E. kuehniella. In the study of the effect of different concentrations of M. anisopliae on the parasitized rate of hosts eggs showed that at low concentrations there is no significant difference between treatments and control, but in higher concentrations, a significant difference was observed, and mean of parasitized eggs was higher in the control. The results of present study confirm that in the simultaneous use of two biological agents, more attention should be paid to the interaction between them to control of target pest.