Population models for the cabbage aphid, Brevicoryne brassicae (L)

aimed to p ro v id e a b e tte r u n de rsta n d ing o f th e po pu la t io n dynamics o f B re vicoryn e b ra s s ic a e ( L .) w ith in th e summer season.I t s p rim a ry p a r a s ito id , D ia e r e t ie lla rapae (M cIntosh) was a ls o co n sid e re d .S p e c ia l emphasis has been placed on th e c o n s tru c tio n o f stage s p e c if ic p o p u la tio n models in v o lv in g d e n s ity dependence, in an a tte m p t to des c r ib e th e flu c tu a tio n s o f b ra s s ic a e th ro u gh th e summer and th e r o le p laye d by [).rapae in r e g u la tin g th e aphid p o p u la tio n s .The sta g e d is t r ib u t io n s o f E3. b ra s s ic a e have been in v e s tig a te d in th e f i e l d and la b o ra to ry , u sing B ru sse ls s p ro u ts as th e a p h id 's h o st p la n t. S e ve ral methods have been compared and used to e v a lu a te th e s t a b i l i t y o f th e stage d is t r ib u t io n o f B^. b ra s s ic a e p o p u la tio n under v a rio u s con d it io n s .Evidence suggests th a t th e stage d is t r ib u t io n s were a ffe c te d by p o p u la tio n d e n s ity .In th e la b o r a to r y , th e im portance o f d e n s ity de pendence in r e g u la tin g J3. b ra s s ic a e p o p u la tio n s has been assessed and 2 .3.1 P o p u la tio n Growth o f E3. b ra s s ic a e ........................ 36 2 .3.2Stage D is tr ib u t io n s in J3. b ra ssica e P o p u la tio n s ................................