Continued concern about fragmentation has led to Android losing some of its lustre for developers, according to the latest developer survey from Appcelerator and IDC – although the Google platform remains the clear number two behind Apple’s iOS.

According to the report, Android is seeing “slow erosion,” with interest in smartphones powered by the platform falling by 4.7 points to 78.6 percent, and Android tablets falling by 2.2 points to 65.9 percent. It was said that although these numbers are “close to or within the margins of error,” they are consistent with a gradual drop in Android interest from previous surveys, even as growth in Android unit shipments continued.

Appcelerator and IDC suggested that this was the result of fragmentation in the Android ecosystem, as well as the continued strength of iOS as an alternative. iOS continues to be number one for developer interest, at 89 percent interest levels for the iPhone, and 88 percent for the iPad.

Interest in Microsoft’s Windows Phone platform remains high, with this being a clear “number three” OS behind iOS and Android. A huge jump in interest recorded in the fourth quarter of 2011 is holding steady, despite “somewhat disappointing” WP7 device sales to date.

Contrastingly, interest in RIM’s BlackBerry saw another sharp drop, falling to 15.5 percent from 20.7 percent in the prior sequential quarter.

HTML5 is also seeing significant interest, ranking close to Android in terms of developer interest. Further details of Appcelerator and IDC’s study can be found here.