PROGRESS REPORT OF THE 1998 7 SPOT LADYBIRD SURVEY

There are many people I would like to thank for help of one sort or another during the survey, especially those members of the airwaves and paper media who have enabled me to bring ladybirds, and my work on them, to the attention of large audiences. But, of course, my greatest thanks goes to the thousands of people who showed an interest in the research and to those who managed to find ladybirds to send in to me. Without them this project would never have got off the ground.

Results
Unfortunately for the gardener and grower, it has been a great year for aphids and the things that eat aphids are of course ladybirds. Many of the people who were interested in taking part in the survey contacted me saying that they had not seen a single ladybird this year and wondered if this was the effect of the parasitic wasp (Dinocampus coccinellae). I cannot solely blame the wasp for the lack of ladybirds but it may well be a contributing factor. It has been a terrible year for ladybirds, the worst since records of such things began, mainly due to the poor summer we've just had. Ladybird populations are responsive to weather, they like it warm and sunny; when it is cold and wet ladybirds find it impossible to mate. During the critical period of late spring and early summer this year it was cool and damp, and the ladybirds simply didn't want to mate.

Even with all this doom and gloom around, you the public came up trumps and managed to get out there and find some for me. In fact, you managed to find 2605, 7-spot ladybirds. These came from just over 200 samples and preliminary studies have indicated that the parasitism of ladybirds is much more widely spread that previously reported. The samples covered 92, 10km squares and were from the borders of Scotland up to the Black Isle, with a sample even coming from N. Uist. More females than males were found, 1403 females, 54% of the total number of ladybirds compared to 1202 males, 46%. However the parasitism rates of females versus males were not significantly different, 508 females compared to 396 males were infected.

But when the map of Scotland is divided into 10km squares and all the samples found in each square are combined to make one total sample, the rates of parasitism range from 0% to over 80%. The range of parasitism found in the 92, 10km squares can be seen by clicking on the map.

Bearing in mind that an acceptable level (if there is such a thing) of parasitism is between 1-20%, the results show 83% of the total area sampled has dangerously high levels of parasitism. In fact 36% of this area would be considered devastating towards the 7 spot ladybird population if the trend continues.

The first ladybird was found in the beginning of March, and most of the ladybirds found early on were female and infected. Again the majority of ladybirds were found in March, April and May, with only 10% being found in June, July and August. One theory why most of the earlier ladybirds found were infected, is that as the wasp has over-wintered inside the ladybird as a first stage larva, it triggers the ladybird into starting to search for food early as the larva needs to start its development. This then makes the ladybird visible as it searches plants for food, probably nectar from spring flowers, as it is too early for aphids. Even single female ladybirds found early on were infected. Again the wasp larva may favour to over-winter in females rather than males because the females lay down a greater fat content. Also in the spring the female ladybirds will search longer and harder for food because they require more than the males to enable egg production to commence later on. This in turn will be beneficial for the developing wasp larva as the more the ladybird eats the quicker the larva will develop and exit to make a cocoon. Remember one wasp with two generations a year has the capacity of killing 10,000 ladybirds in a summer.

The above results are worrying with such high rates of parasitism, especially as it was such a poor year for ladybirds. Therefore I plan to run a similar survey in 1999, but also to try and establish just how many different species of ladybird there are in Scotland. I hope also that I can encourage more people to take part, especially from the North of Scotland, as this year I did not receive any samples from north of the Black Isle. Alongside the survey I launched a competition for youngsters associated with my research with a first prize of £100, second £50, third £25 and finally 5X£5 book tokens. The idea was to design a scientific project associated with ladybirds. I have put together a video that explains more clearly the situation in order thaat teachers or group leaders could stimulate the children's ideas. The video is available directly from SCRI. The competition entries were judged on their scientific content and innovation. Projects, which involve a sizeable team of participants or members of the public, were encouraged. The aim of the project was to encourage the participation and understanding of youngsters in an active science project. So little is known about ladybirds in Scotland that almost anything that is done to study these insects may be useful and novel.

Progress report of the 1999 survey

Progress report of the 2000 survey

References

Micscape article