Their impact on plants combined with the ability to reproduce parthenogenetically makes the aphid a formidable foe – but there is a defense.
Here's a stare down between an aphid and the seven-spot ladybug Coccinella septempunctata:
The predatory attack of Coccinella septempunctata - the aphid hunter:
Coccinella septempunctata is one of several ladybeetles found in Florida, for a listing click HERE.
Throughout the United States non-native coccinellid populations are on the rise. The primary reason for this increase is most likely the establishment of exotic ladybeetles with the ability to out compete, the locals for vital food resources.
For native Florida ladybugs, those food resources are aphids, and with the exception of Neoharmonia venusta, which is a predator of psyllids (jumping plant lice), all of beetles listed above find them quite delicious.
Another contributing factor to native beetle strife may be the commercial sale and transport of ladybeetles for the purpose of agricultural defense. Although the beetles are a tremendous aid in protecting crops, the increased cross-regional exchange of fauna may be accelerating the spread of pathogenic and parasitic organisms that prey on the ladybugs.
In regards to natives being out competed for food resources, Susan Moser and John Obrycki of the University of Kentucky found that when food resources are plentiful exotic ladybeetle species, such as Harmonia axyridis and Coccinella septempunctata experience higher fecundity than the locales and can expand their numbers very quickly. When food resources aren’t as accessible the natives prove to be a heartier species and sustain reproductive rates that out pace the immigrants.
Moser, S., & Obrycki, J. (2009). Competition and Intraguild Predation Among Three Species of Coccinellids (Coleoptera: Coccinellidae) Annals of the Entomological Society of America, 102 (3), 419-425 DOI: 10.1603/008.102.0310