Prospects for the control of apple leaf midge Dasineura mali (Diptera: Cecidomyiidae) by mass trapping with pheromone lures

Abstract

The attractiveness of the pheromone, monophagous habit and low mobility of D. mali enhance the prospects for successful mass trapping. Countering this are high populations, multivoltinism and aspects of mating behaviour. Mass trapping would probably have been more effective had it been in place season long and conducted over successive years. It needs refinements and more study before becoming a feasible control option for D. mali.

Spatial analysis of mass trapping: how close is close enough?

“…38 Suppression of D. mali appears to be promising from these tests, but other factors can be very important to the outcome, such as multiple mating by males, which is known to be an issue because it dilutes the population suppression effect from a reduced impact on the mating rate of females. 20 High density and reproductive rate as well as female dispersal into the plots at 750 traps ha −1 likely led to shoot damage reductions of only ∼50%, 26 which supports the need for areawide treatment. Treating larger areas with male removal should solve immigration problems.…”

“…A total of 29 traps (of 750) were cleared in each of four replicate plots. This number was determined as adequate in a related study which indicated sharp boundaries on the edge of plots, with rapid drop in catch inwards …”

“…This number was determined as adequate in a related study which indicated sharp boundaries on the edge of plots, with rapid drop in catch inwards. 26 In order to confirm the effect of mass trapping density on catch per trap, traps were next deployed in four replicate 1 ha orchard blocks at each of three trap densities over a constant area over the same period: 4, 16 and 750 traps ha −1 (Table 1). Catches from 7 February to 9 March in four traps within each block were used for comparison between trap densities.…”

“…Field trials with 500 traps ha −1 achieved 96% communication disruption of apple leaf curling midge at a 1 ha scale, indicating a potentially successful system . Mass trapping experiments revealed very high levels of trap competition, evidenced by subsampling using transects of traps from the sides of the plot towards the centre . The high catches at corners and the low catches in plot centres led us to the hypothesis that square arrays of as few as 16 traps could be used to measure trap competition by quantifying the difference in trap catches between corner and centre traps.…”

“…20 Mass trapping experiments revealed very high levels of trap competition, evidenced by subsampling using transects of traps from the sides of the plot towards the centre. 26 The high catches at corners and the low catches in plot centres led us to the hypothesis that square arrays of as few as 16 traps could be used to measure trap competition by quantifying the difference in trap catches between corner and centre traps. In each 4 × 4 grid there are four corner, four centre (= middle) and eight edge (= side) traps.…”