|Legaspi, Jesusa - Susie|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2004
Publication Date: 3/31/2005
Citation: Legaspi, J.C., Legaspi, B. 2005. Body weights and egg loads in field-collected Podisus maculiventris (Heteroptera:Pentatomidae). Florida Entomologist. 88(1):38-42.
Interpretive Summary: The spined soldier bug feeds on many insect pest species in different crop environments throughout North America. The bug helps to control pests naturally, and is also sold as a commercial control agent. Many studies have been completed on laboratory individuals, but relatively little is known about its biology in the field. A deeper understanding of how the bug behaves in the field can allow us to use it more effectively as a control agent against pests. We collected the bug in grape vineyards in Florida from April to November, 2003. The weights of the insects collected were compared against laboratory specimens where the amount of feeding was measured. Field weights were quite low, suggesting that field populations ate about 1 prey item every 3 to 9 days. Moreover, we found evidence that the bug constantly produces eggs throughout its lifetime. This characteristic (called "synovigeny") has never before been proven in this type of insect. The results we obtained in Florida were similar to those we found earlier in Indiana, suggesting that the bug plays similar roles, despite differences in crop and climate. In both states, our findings suggest that the bug cannot control very high numbers of insect pests, but can survive prolonged periods of starvation. Therefore, the spined soldier bug may be a useful complementary control agent during period of low pest infestation, but will have to be complemented with another agent during pest outbreaks.
Technical Abstract: Body weights and egg loads of field populations of the spined soldier bug,Podisus maculiventris (Say) (Heteroptera: Pentatomidae) were studied for muscadine grape vineyards in Florida from April to November, 2003. Two main generation peaks were found in June and October. Mean female body weight throughout the year was similar to those obtained in various crops in Indiana. In both studies, body weights were comparable to those found in laboratory experiments where females were fed 1 prey item every 3 to 9 days. Egg loads in Florida were similar to those found in field populations of Indiana. The increase in numbers of immature eggs later in the Florida season may be an indication of continued egg production in older females. We interpret this as possible evidence of synovigeny in the field population. This result is consistent with previous laboratory data showing that immature eggs are continuously produced throughout female lifetime. Larger females predictably had higher mean egg loads. The similarity in biological characteristics found in field populations of Indiana and Florida suggest that the predator has similar impacts on pest species by low feeding rates.