Development of a simulation model for the population dynamics of the onion fly Delia antiqua in Germany*

Abstract

Delia antiqua is a serious pest of many species of the genus Allium, including onions and chives. Over a period of two years (1997/1999), we have developed a model to simulate the population dynamics of D. antiqua based on an extended Leslie model. The model structure as well as the developmental functions for the different life stages of D. antiqua are presented. Using daily mean air and soil temperatures, the model calculates the population matrix for developmental stages of D. antiqua including eggs, larvae, pupae and adults. The simulation can be used to optimize the timing of control measurements against a specific life stage of D. antiqua. Flight activity can be simulated using wind speed as additional information. Simulated flight activity and the observed flight activity of D. antiqua monitored with water pan traps in three different regions of Germany in 1998 are presented and discussed. The model, which was programmed as part of the SWAT 3.5 package of programs to simulate the population dynamics of root-fly pests in horticultural crops, will also be available via other expert systems such as PASO.

Effect of Soil Temperature and Moisture on Survival of Eggs and First-Instar Larvae of Delia radicum

“…Another study showed that D. radicum eggs do not survive exposure to 42ЊC for 1 h (Swailes 1963). A similar value was obtained for D. antique eggs, with all individuals dying at 40ЊC (Otto and Hommes 2000). The LT 50 value we estimated in the laboratory (37.5ЊC) was higher than the temperatures measured at a depth of 2.5 cm in the rutabaga Þeld (Ͻ35.8ЊC during both seasons).…”

Field monitoring of onion maggot (Delia antiqua) fly through improved trapping

“…Past efforts at monitoring and understanding D. antiqua phenology have relied on three principal methods: sticky traps, water traps and simulation. Sticky traps and water traps have been used to varying degrees of success in North America and Europe but often suffer from limitations related to inefficiencies in counting (Otto & Hommes, 2000; Thöming, Schjøll, & Johansen, 2018). Trap catch of adult D. antiqua flies can be low compared to field populations.…”

“…Improved trapping ability of white large diameter traps may improve monitoring efforts in situations where it is desirable to understand D. antiqua phenology, develop decision support tools, measure range, and understand inter‐ and intra‐generational spatiotemporal dynamics. This improved trapping could then inform modelling efforts and predictive management abilities (Ning et al, 2017; Otto & Hommes, 2000; Thöming et al, 2018).…”

“…Odour sources of attractants also have been added to traps in an effort to make them more attractive, but with limited success. Simulation has relied on field data from traps, phenological studies in the laboratory and climate information (Ning et al, 2017; Otto & Hommes, 2000; Thöming et al, 2018). Population simulations can prove useful at larger scales, but often lack extremely detailed location‐specific information necessary for producers to determine whether they have a severe problem in a specific field.…”

“…To further develop effective monitoring methodologies for the D. antiqua , we evaluated a number of factors likely to influence attraction of adult D. antiqua flies. Previous work has suggested that colour, shape, size and chemistry all affect attraction of adult D. antiqua (Harris & Miller, 1983, 1988; Otto & Hommes, 2000; Thöming et al, 2018). We expanded on previous work in field trials over 2 years in upstate New York where a variety of novel trap designs with varying shape, size, colour and chemistry were evaluated to capture adult D. antiqua .…”