Title: Ovigeny in selected generalist predators Authors
|Legaspi,jr, Benjamin - STATE OF FLORIDA|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 24, 2007
Publication Date: March 1, 2008
Citation: Legaspi, J.C., Legaspi,Jr, B.C. 2008. Ovigeny in selected generalist predators. Florida Entomologist. 91(1):133-135. Interpretive Summary: We studied the egg production or ovigeny in common general insect predators. “Pro-ovigenic” insects emerge with a fixed number of mature eggs while “synovigenic” insects continuously produce and develop eggs throughout their adult period. The four predator species we studied were the following: the spined soldier bug, Podisus maculiventris; minute pirate bug, Orius insidiosus; a ladybeetle, Delphastus catalinae and the big-eyed bug, Geocoris punctipes. In the laboratory, we recorded the number of eggs laid by each female predator species through time. At certain time intervals, the predators were sacrificed and dissected to determine the number of mature and immature eggs in their ovaries. We found that all the female predator species developed and laid eggs through their adult stage. In addition, the number of immature eggs in the ovaries increased with predator age while the number of mature eggs decreased, showing evidence that females continuously produced eggs. Our results indicate that the predators are synovigenic. We discuss the significance of these results in evaluating these predators as natural control agents.
Technical Abstract: “Ovigeny” refers to the process of egg production in adult insects. “Pro-ovigenic” adult insects emerge with a fixed complement of mature eggs; whereas, “synovigenic” species continuously produce and develop eggs throughout adulthood. Very little work has been done on ovigeny in insect predators. We studied four predators such as Podisus maculiventris (Heteroptera: Pentatomidae), Orius insidiosus (Heteroptera: Anthocoridae), Delphastus catalinae (Coleoptera: Coccinellidae), and Geocoris punctipes (Heteroptera: Lygaeidae). We examined egg load at regular intervals (dependent on lifespan). Numbers of eggs laid were also recorded. In P. maculiventris, numbers of immature eggs increased with predator age whereas numbers of mature eggs declined providing clear indication of continuous egg production. Similar results were found in G. punctipes. In other predators, egg loads tended to increase with time, except in D. catalinae. However, numbers of eggs laid all increased with time. These findings suggest that egg production occurs during the adult stage in all these predators and that all predators studied were synovigenic to varying degrees. We discuss possible implications in the evaluation of predatory biological control agents.