Efficacy of Echium spp. water extracts as post-harvest grain protectants against Plodia interpunctella

Water extracts of three plant species of the genus Echium (E. italicum L., E. vulgare L. and E. rubrum Jacq.) were tested under laboratory conditions for their activity as potential post-harvest grain protectants against Plodia interpunctella (Hubner, 1813) (Lepidoptera: Pyralidae) larvae. Antioxidative activity and total phenolic, flavonoid and tannin contents in plant extracts were determined. The larvicidal assays were conducted with the local population of P. interpunctella from Central Serbia on kernels of Takovoanka winter wheat cultivar. The experiment was set as factorial 3x3x3x3 block design type. Three groups of larvae of different maturity were used. The larvae were exposed to three different concentrations of water extracts (1%, 2% and 5%) of three listed plant species. Mortality was registered daily during 96 hours and the efficacy was calculated using Schneider-Orelli's formula. The largest number of dead larvae was recorded in the treatment of 1% extract of E. italicum on youngest group, after 72 and 96 h. Extracts of E. vulgare and E. rubrum did not show high larvicidal effect

Influence of maize kernel state and type on life history of Plodia interpunctella (Lepidoptera: Pyralidae)

The objective of this study was to investigate the influence of different mechanical states (whole, broken and ground kernels) and types (dent, semi-flint and flint) of maize kernels on life history parameters of Plodia interpunctella (Hubner), the Indian meal moth. These parameters included larval development and its dynamics, adult emergence, mean development duration (MDD) and fecundity. Since the larvae are the developmental stage that causes the most damage on maize, additional data on larval development helps identify conditions that promote development. The results of our study indicate that broken maize kernels are the most suitable for P. interpunctella development, where the most successful larval development, the highest number of emerged adults, the shortest MDD and the highest total fecundity were recorded. On the contrary, whole kernels were the least suitable and the most resistant to infestation by P. interpunctella. The type of kernel also significantly affects P. interpunctella developmental parameters. Females reared on flint kernels (the hardest kernel type tested in our study) laid the largest total number of eggs, which implies that kernel hardness, i.e. the type of kernel should be an important parameter when choosing maize hybrids for cultivation and for storage. Our study warrants further investigation of maize types and their susceptibility to P. interpunctella

Life history of Plodia interpunctella (Lepidoptera: Pyralidae) on dried fruits and nuts: Effects of macronutrients and secondary metabolites on immature stages

The objective of this study was to investigate the effects of nutrients and secondary metabolites content in 16 types of dried fruits and four nuts from Serbia on life history traits of Plodia interpunctella (Hubner, 1813) immature stages. The analysis of nutrients content included determination of the total moisture, ash, proteins, fats, carbohydrates, sugars, and total reducing sugars, while from secondary metabolites total phenolics, flavonoids and tannins contents were determined. Life history traits included the developmental duration of larvae (LDD), developmental duration of pupae (PDD) and total immature stages (MDD), as well as the survival of larvae and pupae. Additional analyses was conducted on time specific survival, as well as on the age-and size-growth patterns of P. interpunctella larvae. The principal component analysis (PCA) indicated that the content of proteins and fats is in strong positive correlation with larval and total immature stages survival, while in negative correlation with LDD, PDD, and MDD. The content of secondary metabolites are in strong positive correlation with LDD and MDD, while in negative correlation with larval and total immature stages survival. Considering the fastest development and high number of survived larvae and pupae, the walnuts, hazelnuts and almonds were more suitable for the development of P interpunctella than tested dried fruits in general, while the goji berries and figs were the most suitable among tested dried fruits. The results of the effects of tested dried fruits and nuts from Serbia on life history traits of P. interpunctella, combined with studies from different countiries using local varieties and cultivars of dried fruits and nuts, could provide the data for modeling the growth and population dynamics, important for forcasting and signaling the occurance of this pest