The development of the asparagus miner (Ophiomyia simplex Loew; Diptera: Agromyzidae) in temperate zones: a degree-day model

Aeration to Manage Insects in Wheat Stored in the Balkan Peninsula: Computer Simulations Using Historical Weather Data

Wheat is one of the major crops throughout the Balkan peninsula of Europe. Specific harvest and binning dates can vary depending on the specific geographic region. Grain aeration, wherein ambient air is used at low-volume airflow rates to cool a grain mass to levels that will suppress insect population development, is an under-utilized component of pest management plans for stored wheat. The successful use of aeration can potentially reduce fumigation of stored wheat, which will contribute to the amelioration of increasingly prevalent phosphine resistance. Historical weather data were used from 19 sites in the Balkan region to predict how quickly grains could be cooled through the use of aeration, using a web-based aeration model, and three different starting dates, including 1, 15, and 30 July. The model was used to predict population growth and development of Sitophilus oryzae, the rice weevil, with and without the use of aeration. Results show that, in the northern regions of the Balkans, aeration implemented at the start of binning reduced insect populations far below pest levels in unaerated wheat, and may potentially eliminate the need for fumigations. In more southerly regions, additional chemical inputs, such as fumigation or grain protectants, may be necessary in conjunction with aeration. Results provide guidelines for the increased potential of using aeration for the management of wheat produced and stored in the Balkan peninsula.

Feasibility of Using Aeration to Cool Wheat Stored in Slovenia: A Predictive Modeling Approach Using Historical Weather Data

The use of aeration, which refers to cooling of a grain mass using low-volume airflow rates with ambient air, is an under-utilized component of management programs. A model simulation study was conducted for the country of Slovenia by examining historical weather data for 10 selected sites to determine if sufficient cooling hours <15 °C were available in August and September to cool stored wheat. The weather data were then coupled with a degree-day model to determine if a generation of Sitophilus oryzae (L.), the rice weevil, could be produced in the absence of aeration, using a start date of 1 August. The weather data for September was used to classify Slovenia into different risk zones, depending on the number hours <15 °C. Three sites from each zone, from warmest to coolest, Portorož, Novo Mesto, and Lesce, were further examined using a web-based aeration model and insect population growth model for S. oryzae developed by Texas A&M University Beaumont TX for cooling stored rough rice, to predict bin temperatures and population growth from 1 August to 30 November. The results show that, for most of Slovenia, in the absence of aeration, a complete generation of S. oryzae could occur based on an infestation beginning 1 August. The use of aeration immediately cooled stored wheat in the three selected sites, resulting in a dramatic decrease in predicted populations of S. oryzae in aerated wheat compared to unaerated wheat. The results show that the use of aeration may be expanded in Slovenia for management of stored commodities, and it could help alleviate dependence on insecticides for insect pest management after harvest.

A new method of estimating thermal performance of embryonic development rate yields accurate prediction of embryonic age in wild reptile nests

Temperature has a strong effect on ectotherm development rate. It is therefore possible to construct predictive models of development that rely solely on temperature, which have applications in a range of biological fields. Here, we leverage a reference series of development stages for embryos of the turtle Chelydra serpentina, which was described at a constant temperature of 20 °C. The reference series acts to map each distinct developmental stage onto embryonic age (in days) at 20 °C. By extension, an embryo taken from any given incubation environment, once staged, can be assigned an equivalent age at 20 °C. We call this concept "Equivalent Development", as it maps the development stage of an embryo incubated at a given temperature to its equivalent age at a reference temperature. In the laboratory, we used the concept of Equivalent Development to estimate development rate of embryos of C. serpentina across a series of constant temperatures. Using these estimates of development rate, we created a thermal performance curve measured in units of Equivalent Development (TPC_ED). We then used the TPC_ED to predict developmental stage of embryos in several natural turtle nests across six years. We found that 85% of the variation of development stage in natural nests could be explained. Further, we compared the predictive accuracy of the model based on the TPC_ED to the predictive accuracy of a degree-day model, where development is assumed to be linearly related to temperature and the amount of accumulated heat is summed over time. Information theory suggested that the model based on the TPC_ED better describes variation in developmental stage in wild nests than the degree-day model. We suggest the concept of Equivalent Development has several strengths and can be broadly applied. In particular, studies on temperature-dependent sex determination may be facilitated by the concept of Equivalent Development, as development age maps directly onto the developmental series of the organism, allowing critical periods of sex determination to be delineated without invasive sampling, even under fluctuating temperature.

Diurnal temperature variations affect development of a herbivorous arthropod pest and its predators

The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen’s inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and +15°C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally alternating temperatures resulted in a faster development in the lower temperature range as compared to their corresponding mean constant temperatures, whereas the opposite was observed in the higher temperature range. Our results indicate that Jensen’s inequality does not suffice to fully explain the differences in developmental rates at constant and alternating temperatures, suggesting additional physiological responses play a role. It is concluded that diurnal temperature range should not be ignored and should be incorporated in predictive models on the phenology of arthropod pests and their natural enemies and their performance in biological control programmes.