[R-sig-ME] malaria data set question

[Georgina Sarah Humphreys]

I have a data set of number of malaria parasite genomes inside single oocysts (like egg sacks) dissected from guts of mosquitoes.  The data set includes some single oocysts that were collected from the same mosquitoes and multiple different experiments, conducted on different days.

The question I want to ask is:
Are the genome numbers in single oocysts associated with any of three variables measured -
1. number of oocysts on the gut (continuous)
2. the wing length of the mosquito (continuous)
3. the species of the parasite used (binary)
I also have the random effect of the mosquito nested in the random effect of experiment.

I have tried the following model;
model <- lmer(genomes~oocysts+wingsize+species+(1|mosq)+(1|expt), REML=FALSE)

But I'm not sure this is correct... should I use (1|mosq:expt) instead? 

Any help would be gratefully received - I have to hand-in my thesis in 10 days, and I'm new to lmer!
Many thanks in advance,
Georgina
PhD Student
Division of Infection and Immunity
B5-29, GBRC
120 University Place
Glasgow
G12 8TA
Tel: 0141 330 5650