Courtship behaviour in the field cricket species, Gryllus bimaculatus, involves male crickets producing different vocalizations (songs) to:
Scientists investigated cricket courtship behaviour by feeding a population of sexually active male crickets a diet containing the neonicotinoid pesticide imidacloprid (IMI). The scientists also fed a separate control population of sexually active male crickets a diet without IMI.
They determined the percentage of males making calling songs or aggressive songs in each population.
Table 1 shows their results.
| Population | Percentage of males making calling songs (%) | Percentage of males making aggressive songs (%) |
|---|---|---|
| Males fed IMI | 86.5 | 10.5 |
| Males not fed IMI (control) | 92.5 | 3.5 |
There were 650650650 males in the control population. Each male made only one type of song.
Use this information and Table 1 to calculate the number of males making courtship songs in the control population.
Suggest one change the scientists could make to both cricket populations to increase the number of male courtship songs.
The scientists also investigated the effect on female cricket courtship behaviour of exposing male crickets to IMI. Table 2 shows their results.
Table 2
| Population | Median time spent by females in courtship (s) |
|---|---|
| Males fed IMI | 12 |
| Males not fed IMI (control) | 24 |
Imidacloprid (IMI) is a widely used agricultural pesticide that can leach into surrounding habitats via agricultural runoff, contaminating wild cricket habitats.
Suggest and explain the effect that IMI pollution in wild cricket habitats will have on cricket reproduction. Use information from Table 1 and Table 2 in your answer.