PROF PJ TAYLOR
PROJECT TITLE:
Pilot study to investigate the potential importance of bats as biocontrol agents suppressing nocturnal flying pests in macadamia orchards.
Two Univen student 4th year projects completed in the past two years have investigated the diet of two different species of bats which roost in or near macadamia orchards in Levubu (slit-faced bat and Angolan free-tailed bats); two further studies (on the diet of the yellow house bat and African pipistrelle bats) will be submitted for examination by the end of 2012 although data from the African pipistrelle are already available.
Microscopic analysis of bat droppings collected from bat roosts revealed that at least three bat species consumed greater proportions of bugs (Order Heteroptera) than found in natural areas but the technique was not able to differentiate stinkbugs (Family Pentatomidae) from other bugs.
To address this, in collaboration with the University of Copenhagen we will shortly be conducting “next-generation” DNA sequencing analyses of bat droppings of six locally occurring species to determine in more detail the insect groups present in the diet of bats. The project will form part of a Univen MSC study (Emmanual Matamba) supervised by Prof Taylor and Dr Nangammbi of Univen and Prof Tom Gilbert of the University of Copenhagen. During November 2012, Dr Nangammbi and Mr Matamba will travel to Copenhagen with samples of bat faecal pellets and at least 10 locally-occurring stinkbug species (collected by Koos Steyn from Levubu) in order to receive the relevant training and commence the laboratory work which will hopefully establish in greater detail which stinkbug and other pest insect species may be present in the diet of different groups of bats feeding over macadamia orchards in Levubu.
Additional student projects using ANABAT bat detectors have revealed that patterns of habitat use of macadamia orchards on one macadamia farm tested so far (Welgevonden) are distinctly seasonal, with much activity being concentrated in late summer-autumn which is the time when stinkbug numbers peak.
However, causality of this correlation remains to be tested by censusing insects including stinkbugs throughout the year at the same site (this is ongoing and forms part of Koos Steyn’s PHD research at UNIVEN) as well as establishing the proportion of stinkbugs in the diet of locally-occurring bats (as described above).
Finally, we are ready to commence with trials of bat houses on a range of macadamia farms at Piesanghoek and Levubu. Temperature monitoring (using ibuttons) of bat houses as well as occupied attic roosts of bats will be conducted to determine the best bat house designs and placement principles to ensure successful occupation by bats.
