Cellular Energy Allocation of Tuta absoluta (Lepidoptera: Gelechiidae) treated with Flubendiamide and Thiocyclam Hydrogen Oxalate on Different Tomato Cultivars.

The tomato leaf miner, Tuta absoluta (Meyrick), is the most important pest for tomato production in Iran. The effect of flubendiamide and thiocyclam hydrogen oxalate insecticides was assessed on cellular energy allocation (CEA) of the third instar larvae of T. absoluta ingesting six different tomato cultivars. Plant leaves were treated with LC50 concentration of both insecticides and their energy available (Ea), energy consumption (Ec), and CEA were calculated. The results showed that total energy reserves (protein, carbohydrate, and lipid budgets) were significantly reduced after exposure to insecticides and tomato secondary metabolites. The larvae fed on Riogrande and Super Chief cultivars showed the least amount of energy available after treatment with both insecticides. The highest rate of oxygen consumption was observed in larvae fed on Calj, Super Luna, and Super strain B after treatment with flubendiamide. The amount of CEA decreased in treated larvae compared to untreated larvae. This reduction was statistically higher in treated larvae that fed on Riogrande and Super strain B cultivars. Reduction in CEA is probably due to the expenses of dealing with detoxification of insecticides and plant metabolites. CEA is a suitable and primary biomarker for the effects of cultivars and insecticides as integrate and summarizes insect energy allocation in variable situations.

Side effects of chlorantraniliprole, phosalone and spinosad on the egg parasitoid, Trichogramma brassicae.

The combined use of chemicals and biological control is not always a successful strategy owing to the potential side effects on biocontrol agents. Lethal and sublethal effects of three commonly used insecticides were assessed on adult and immature stages of the egg parasitoid Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae). Recommended field concentrations of chlorantraniliprole, phosalone and spinosad caused mortality on preimaginal stages by 24, 87, and 98%, respectively. Lethal effects on parasitoid adults exposed to the insecticide dry residues were estimated as median lethal concentrations (LC50) that were 13.28, 0.25, and 0.03 µg a.i. ml-1 for chlorantraniliprole, phosalone, and spinosad, respectively. The effect of a low lethal concentration (LC30) of the compounds was evaluated on various adult biological traits, such as longevity, fecundity, emergence rate and other life table parameters. All compounds caused detrimental effects on all the estimated demographical indexes. Chlorantraniliprole affected the net reproductive rate, mean generation time and doubling time in comparison to the control; while, phosalone and spinosad adversely affected all assessed parameters. Phosalone and spinosad significantly reduced gross reproductive rate, net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time and doubling time and reduced longevity, fecundity, emergence rate related to other biological parameters in comparison with control. The results suggest that all compounds are not fully compatible with the activity of T. brassicae, and that the inclusion of chlorantraniprole, spinosad and phosalone into Integrated Pest Management (IPM) involving this parasitoid has to be avoided. Nevertheless, further studies in open field conditions and on a multiple generation scale are necessary for providing a more definitive conclusion on the IPM suitability of the three tested insectcides.

Composition, Antifungal, Phytotoxic, and Insecticidal Activities of Thymus kotschyanus Essential Oil.

Essential oils (EOs) are some of the outstanding compounds found in Thymus that can exert antifungal, phytotoxic, and insecticidal activities, which encourage their exploration and potential use for agricultural and food purposes. The essential oils (EO) obtained from Thymus kotschyanus collected in the East Azerbaijan Province (Iran) were characterized using a gas chromatography-mass spectrometry (GC-MS) analysis. Thymol was the most important compound (60.48%), although 35 other active compounds were identified in the EO. Significant amounts of carvacrol (3.08%), p-cymene (5.56%), and γ-terpinene (6.67%) were found in the EO. The T. kotschyanus EO was tested against important phytopathogenic fungi (Botrytis cinerea, Aspergillus niger, and Penicillium expansum). The antifungal assay showed that the use of ≥500 ppm of EO resulted in a fungicidal effect against all funguses tested. In a similar way, the use of ≥500 ppm of EO inhibited the germination of all crop weed seeds (Amaranthus retroflexus L. and Panicum miliaceum L.) and their subsequent growth, which demonstrated its herbicidal effect. Finally, the insecticidal capacity of T. kotschyanus EO was also observed against selected insects (Oryzaephilus surinamensis and Sitophilus oryzae). O. surinamensis was more susceptible to the effect of EO (LC50 = 4.78 µL/L air) than S. oryzae (LC50 = 13.20 µL/L air). The obtained results of the present study can provide new safe resources to the development of new products for the food, agriculture, and pharmaceutical industries.

Fitness costs to Helicoverpa armigera after exposure to sub-lethal concentrations of Metarhizium anisopliae sensu lato: Study on F1 generation.

The entomopathogenic fungus, Metarhizium anisopliae (Metsch.) Sorokin is a valuable biocontrol agent attacking larval stages of many lepidopteran pests including Helicoverpa armigera (Hübner). Sub-lethal effects of M. anisopliae sensu lato (s.l.) (isolate M14) were investigated on life table parameters of offspring from treated larvae of H. armigera. Duration of different life stages was significantly affected by fungal treatments. Fecundity was decreased in females derived from H. armigera larvae treated with M. anisopliae s.l. Sub-lethal concentrations of the entomopathogen reduced the net reproduction rate (R0) of F1 insects for all treatments compared with the control. Similar reductions were observed for the intrinsic and the finite rates of increase (rm and λ, respectively). The mean generation time (T) and the doubling time (DT) were statistically higher in offspring of individuals exposed to some fungal concentrations than control insects. Our results indicated that there was a significant decrease in the F1 population of H. armigera derived from larvae that were exposed to sub-lethal concentrations of M. anisopliae s.l.