Peter Jackson’s protege Neill Blomkamp struck a winner as the R-rated sci-fi allegory District 9 delivered a clear North American number one triumph for TriStar Pictures thanks to an estimated $37m.

Jackson produced the widely admired South Africa-set tale of human inhumanity towards marooned aliens, which features Sharlto Copley at the head of an unknown cast and inspired a 14% box office surge against the same period last year.

Blomkamp, originally lined up to adapt the video game smash Halo for Jackson until Fox and Universal pulled the plug, based his feature debut on his short film Alive In Joberg.

Last weekend’s champion Paramount’s G.I. Joe: The Rise Of Cobra fell to second place on a $98.8m running total in its second weekend, the latest film to add credence to the notion that in terms of percentage drop-offs this season, 60 is the new 50.

G.I. Joe is one of several titles to plummet at least 60% in their second weekends this summer after previous slides by Funny People and Harry Potter And The Half-Blood Prince of 64.8% and 62%, respectively. Bruno holds the dubious distinction of leading the pack after it virtually dropped off the face of the earth several weeks ago with a 72.8% tumble.

Warner Bros secured third place on $19.2m with New Line’s new romance The Time Traveler’s Wife starring Rachel McAdams and Eric Bana, while Paramount Vantage launched comedy The Goods: Live Hard, Sell Hard starring Jeremy Piven in seventh on $5.4m.

Buena Vista’s Hayao Miyazaki’s Ponyo opened in ninth place on $3.5m and the animated release is already a global smash, having amassed more than $180 overseas. Summit’s comedy Bandslam launched in 12th place on $2.3m.

Buena Vista’s G-Force stands at $99m in fifth place after four weekends, while Sony’s Julie & Julia ranks fourth on $43.7m after two. Harry Potter 6 in seventh place has amassed $283.9m for Warner Bros after five weekends and more than $861m worldwide.

Anchor Bay debuted two Sundance acquisitions in limited release. The Ashton Kutcher gigolo romp Spread from David Mackenzie grossed $117,000 from 91 theatres while figures were unavailable for Paul Solet’s festival horror hit Grace, which played in a handful of theatres and is understood to have sold-out Friday and Saturday nights at the Sunset Five in Los Angeles.

Quentin Tarantino returns next weekend as Canes premiere Inglourious Basterds opens through the beleaguered Weinstein Company. Also opening wide are Robert Rodriguez’ children’s film Shorts through Warner Bros and Fox’s comedy Post Grad. Fox has called Friday August 21 Avatar Day in honour of James Cameron’s highly anticipated sci-fi adventure Avatar due out at the end of the year and will show extended footage in select theatres.

Estimated Top 10 North America August 14-16, 2009

Film (Dist)/Est wkd gross/Est total to date

1 (-) District 9 (TriStar) QED Int’l/SPRI $37m –

2 (1) G.I. Joe: The Rise Of Cobra (Paramount) PPI $22.5m $98.8m

3 (-) The Time Traveler’s Wife (Warner Bros) NLI/WBPI $19.2m –

4 (2) Julie & Julia (Sony) SPRI $12.4m $43.7m

5 (3) G-Force (Buena Vista) WDSMPI $6.9m $99m

6 (-) The Goods: Live Hard, Sell Hard (Paramount Vantage) Paramount Vantage Int’l $5.4m –

7 (4) Harry Potter And The Half-Blood Prince (Warner Bros) WBPI $5.2m $283.9m

8 (6) The Ugly Truth (Sony) SPRI $4.5m $77.5m

9 (-) Ponyo (Buena Vista) Wild Bunch $3.5m –

10 (9) 500 Days Of Summer (Fox Searchlight) $3m $17.9m