|
PROGRESS REPORT OF THE 1999 7 SPOT LADYBIRD SURVEY Again my greatest thanks goes to everyone who has become involved and helped in one way or another with my project. Without your continual support I would not have been able to firstly get this project off the ground but secondly I would not have managed to successfully complete so many of my aims. The results of the previous 2 years Scottish survey have indicated a decline in the 7 spot ladybird population. The downward trend of 1997/1998 has continued into 1998/1999. You the general public reported that ladybirds were in even scarcer supply in 1998/1999 and I received less than a quarter of the number of specimens compared to the year previous. Again more females than males were found, 313 females, 61% of the total number of ladybirds compared to 200 males, 39%. However, even though the numbers were lower there were still high rates of parasitism, and in particular female ladybirds were parasitised more than males, which prevents them from reproducing (47% of the female population was infected compared to 35% of the male population). The first ladybird was found in the beginning of April, and most of the ladybirds found early on were female and infected. This year the majority of ladybirds were found later in May, 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 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 repeated high rates of parasitism, especially as it was again such a poor year for ladybirds. Finding other ladybirds appeared to be a problem this last year as well. I received very few sightings of different species, those that were seen were the 2 spot, 10 spot, 11 spot, 14 spot, eyed, orange, cream spotted, striped, pine and larch. Though again numbers of these were small. Therefore I am planning to run both of these surveys for one final year in 2000. This is to give me enough information to establish if this wasp is really effecting the 7 spot population, and to update the species distribution maps. So get out there and start looking, we need as many sight records of different ladybird species as possible. This year a poetry competition was launched for youngsters with cash prizes. All the youngsters had to do waswrite a poem associated with ladybirds and their place in our environment. The video "Ladybird Spot-Checks", which is all about ladybirds is still available, it is informative yet fun and as ladybirds are mini-beasts it easily fits into the school curriculum. |
|
|
Progress report of the 1998 survey |