OUTFLOWS:
DYING_HA1 ¼ ADULTS_H1 * (1 À MASF_H)/DT {Individuals per Time Period}
IMMIG_1_TO_2 ¼ IF ADULTS_H1 À (.1 * ADULTS_H1 + .9 * FRXNL_CAP1)
> 0 THEN (.1 * ADULTS_H1 + .9 * FRXNL_CAP1) ELSE IF ADULTS_H1 > 0
THEN ADULTS_H1 ELSE 0 {Individuals per Time Period; Only healthy
adults migrate. At least ten percent of the healthy adults always migrate. Under
the noted conditions the 10% healthy and an additional fraction of the healthy
adults based empirically on the total number of adults also migrate. Note well the
order of the nested IF statement; the first one is checked first and if the condition
holds the first statement is executed and the program goes no further. Otherwise
all the adults flee. This same statement is also true of the adults in the other
field.}
ADULTS_H2(t) ¼ ADULTS_H2(t À dt) + (MATURE_H2 + INCOMING_2 À
DYING_HA2 À IMMIG_2_TO_1) * dt
INIT ADULTS_H2 ¼ .1 {Initial healthy adults}
INFLOWS:
MATURE_H2 ¼ MNSF_H * NYMPHS_H2 * (1ÀINFECTION_COEF2)/TN1_H
{Individuals per Time Period}
INCOMING_2 ¼ ARRIVING_1_TO_2 {Individuals per Time Period}
OUTFLOWS:
DYING_HA2 ¼ ADULTS_H2 * (1 À MASF_H)/DT {Individuals per Time Period}
IMMIG_2_TO_1 ¼ IF ADULTS_H2 À (.1 * ADULTS_H2 + .9 * FRXNL_CAP2)
> 0 THEN (.1 * ADULTS_H2 + .9 * FRXNL_CAP2) ELSE IF ADULTS_H2 > 0
THEN ADULTS_H2 ELSE 0 {Individuals per Time Period}
CARRY_R1(t) ¼ CARRY_R1(t À dt) + (R_COUNT1 À DUMP1) * dt
INIT CARRY_R1 ¼ 0
INFLOWS:
R_COUNT1 ¼ IF (time MOD 52) ¼ 0 THEN RANDOM(0,1)/DT ELSE 0
OUTFLOWS:
DUMP1 ¼ IF (time MOD 52) ¼ 0 THEN CARRY_R1/DT ELSE 0 {Insures a
new number between 0-1 each integer time step.}
CARRY_R2(t) ¼ CARRY_R2(t À dt) + (R_COUNT2 À DUMP2) * dt
INIT CARRY_R2 ¼ 0 {See note in Carry_R.}
INFLOWS:
R_COUNT2 ¼ IF (time MOD 52) ¼ 0 THEN RANDOM(0,1)/DT ELSE 0
OUTFLOWS:
DUMP2 ¼ IF (time MOD 52) ¼ 0 THEN CARRY_R2/DT ELSE 0
LEAVE_1_TO_2(t) ¼ LEAVE_1_TO_2(t À dt) + (IMMIG_1_TO_2 À DYING_
2_TO_1 À ARRIVING_1_TO_2) * dt
INIT LEAVE_1_TO_2 ¼ 0
INFLOWS:
IMMIG_1_TO_2 ¼ IF ADULTS_H1 - (.1 * ADULTS_H1 + .9 * FRXNL_CAP1)
> 0 THEN (.1 * ADULTS_H1 + .9 * FRXNL_CAP1) ELSE IF ADULTS_H1 > 0
THEN ADULTS_H1 ELSE 0 {Individuals per Time Period; Only healthy
adults migrate. At least ten percent of the healthy adults always migrate.
278
33 Diseased and Healthy Immigrating Insects