Modeling solitary bee abundance

Erica Stevani, Silvia Lomáscolo and Jimena Dorado

Study area: Villavicencio

Reserve

Mendoza

Solitary bee Megachile sp.

Photo Nachu Chacoff

Nest traps

Pho

to B

eni P

adro

n

Larrea divaricata

Objective:Modeling solitary bee abundance along the

floral season in four sites in Villavicencio.

Questions:1-Does the pattern of bee abundance differ

among the sites ?– In what parameters?

2-If they differ, is the difference correlated to habitat degradation?

Deterministic portion:Gaussiany= A*exp(-(x-b)^2/(2*(c^2))

Stochastic portion:Poisson distribution

Our data

mle2(ocupacion~dpois(A*exp(-(dias-b)^2/(2*(c^2)))),start=list(A=7,b=35,c=14),data=ocup.fecha06)

A

b

c

Deterministic portion:Gaussiany= A*exp(-(x-b)^2/(2*(c^2))

Stochastic portion:Poisson distribution

Our data

Question 1:Does the pattern of bee abundance differ

among the sites ? – In what parameters?

A, b, c, similar for all sites

A is different, b and c are similar

A is similar, b and c are different

A, b, c, different for all sites

Bee abundance differs among sites

Log-likelihood = -44.87 Log-likelihood = -34.90

Likelihood Ratio Test: Chi-sq = 19.94, df = 9, p = 0.019

Question 1:Does the pattern of bee abundance differ

among the sites ? YES– In what parameters?

A, b, c, similar for all sites

A is different, b and c are similar

A is similar, b and c are different

A, b, c, different for all sites

Questions:1-Does the pattern of bee abundance differ

among the sites ? YES– In what parameters?

A, b, c, similar for all sites

A is different, b and c are similar

A is similar, b and c are different

A, b, c, different for all sites

ANOVA: Chi-sq = 8.28 df = 6 p = 0.218

ANOVA: Chi-sq = 7.21 df = 3 p = 0.066

In A

Objective:Modeling solitary bee abundance along the

floral season in four sites in Villavicencio.

Questions:1-Does the pattern of bee abundance differ

among the sites ? YES– In what parameters? In A

2-If they differ, is the difference correlated to habitat degradation?

Question 2:Is the difference among sites related to

habitat degradation?

A, b, c, similar for all sites

A is different b and c similar for pristine and degraded sites

A is different, b and c are similar

A is similar, b and c are different

A, b, c, different for all sites

Disturbed and pristine sites have different pattern of bee ocupation

Log-likelihood = -39.59 Log-likelihood = -39.04

Likelihood Ratio Test: Chi-sq = 1.11, df = 2, p = 0.575

Question 2:Is the difference among sites related to

habitat degradation?

A is different b and c similar for pristine and degraded sites

A is different, b and c are similar

A, b, c, similar for all sites

A is similar, b and c are different

A, b, c, different for all sites

Objective:Modeling solitary bee abundance along the

floral season in four sites in Villavicencio.

Questions:1-Does the pattern of bee abundance differ

among the sites ? YES– In what parameters? In A

2-If they differ, is the difference correlated to habitat degradation? IT SEEMS TO BE

General conclusions

1. The nesting pattern varies mainly in number of traps occupied, not so much in the timing.

2. The degraded sites have greater abundance of bee nests.

3. We don’t know why abundance is greater, really…

Thanks!!