2.4. Descriptions of the studies

2.4.1. Egg laying, conspecific presence and encounter rate (I, II)

I studied the effect of conspecific presence on female egg laying, accumulation of eggs in the reproductive tract, and egg production in the field (I). This was examined by enclosing one or two females in a netbag (20 25 cm) that was tied on a sprig of food plant that was naturally growing at the study site. Thus female(s) had a continuous access to fresh food and a possibility to lay eggs on the plant. The experiment lasted six days. I altered conspecific presence after three days in half of the netbags. The four treatments were as follows:

three days: alone three days: alone

three days: paired three days: paired

three days: paired three days: alone

three days: alone three days: paired

The number of eggs that females laid on a conspecific body or on a food plant was counted after both periods. After the experiment, I dissected the females to count the mature eggs in their reproductive tracts. As a measure of egg production, I used the sum of eggs laid during the experiment and the number of eggs in reproductive tract for each female.

I studied the effect of conspecific encounter rate on female egg laying in the laboratory (II). Encounter rate was manipulated by placing two individuals in different sizes of enclosures (small enclosure 7 × 17 cm and large enclosure 21 × 30 cm). In the small enclosures, bugs were unable to avoid each other, and therefore this treatment gave an estimate of how many eggs a female will lay with unlimited access to lay eggs on another bug. In the large enclosures, vegetation was complex and there was plenty of space for bugs to hide and avoided the egg-laying female. The two experiments carried out and treatments within were as follows:

The two experiments lasted for eight days and I counted the number of eggs each female laid on conspecific back daily. I also monitored the number of matings, and after the experiment, I counted the eggs laid on food plant for Experiment B.

2.4.2. Egg survival and egg receiving (III)

Egg survival relative to conspecific host’s sex, body size and egg receiving were studied in Andalusia and Catalonia. The number of eggs and their position on the bug’s body were recorded when individuals were collected for the experiment. Experimental eggs were laid by females under controlled conditions except for one Andalusian study site (site 3) where bugs carried their original eggs. The effect of paternity on egg survival was studied in Catalonia where males carried eggs that were received before or after mating. I drew egg-maps of each bug to identify and to monitor the survival of each experimental egg since bugs may receive eggs or lose eggs during the experiment. Marked bugs were recaptured after two days in Catalonia. In Andalusia, recaptures were carried out three and six days after the initial release. The distribution of eggs on recaptured bugs was compared to the corresponding egg-maps.

2.4.3. Female current fecundity and her behaviour (IV)

The effect of female current fecundity on behaviour was studied both in the field and in the laboratory. First, I examined if females captured from different microhabitats (open, covered) varied in their current fecundity in Andalusia. Female current fecundity was estimated as the eggs laid during the 24 h immediately after capturing. Second, I examined whether differences in microhabitat choice were caused by differences in female current fecundity. In field site in Catalonia, I used a two piece enclosure and introduced gravid and non-gravid females in the inner enclosure and males in the outer enclosure. There was a bush of Lavandula sp in the inner enclosure to provide hiding spots for the females. Once a female had left the inner enclosure, she was unable to return due to the fence that allowed only unidirectional movement. The fence also prevented males from entering the bush area and thus affecting a female’s decision whether to leave or not. I began recaptures 2.5 h after the experiments started. At recapture, it was noted whether a female had left the bush or not, the number of eggs received (for both sexes) and mating status. I also performed a manipulative experiment in the laboratory in order to follow how current fecundity affected the activity of an individual female in the presence of a male. Each enclosure consisted of one gravid and one non-gravid female and one male. They were followed for 4 h. The time (minutes) that each female spent in an open area visible for monitoring or covered under plant material was recorded. The number of male courtings and eggs laid by females were also counted.

2.4.4. Female current fecundity and males (V)

I examined whether males select females according to their current reproductive state, whether courtship is costly for males and if males gain any benefit from their choice of a female. A focal male was enclosed with a gravid and a non-gravid female. I followed the courtings performed by a male. When a focal male began to copulate with one of the females, I removed the other female and placed it with a new male. This was done to estimate how quickly and how many eggs the focal male would have received if he had selected the other female. Once copulation was completed, I measured the time from the end of copulation to female egg laying in both boxes. I also counted the eggs laid before the second copulation, which often took place a day or two after the first one.