Relative longevity of adult Nezara viridula in field cages of cotton,peanut, and soybean

Authors: Olson, Dawn; RUBERSON, JOHN - University Of Georgia; ANDOW, DAVID - University Of Minnesota

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2015
Publication Date: 2/27/2016
Citation: Olson, D.M., Ruberson, J.R., Andow, D.A. 2016. Relative longevity of adult Nezara viridula in field cages of cotton,peanut, and soybean. Entomologia Experimentalis et Applicata. 159:30-36. https://doi.org/10.1111/eea.12408.
DOI: https://doi.org/10.1111/eea.12408

Interpretive Summary: Producers in the Southeastern US face significant crop losses from the stink bugs Nezara viridula, Euschistus servus, and Chinavia hilaris. Cotton, peanut, and soybean are major agronomic crops and host plants of stink bugs in the region. N. viridula colonize and feed in peanut. Stink bugs prefer the seeds/fruit of host plants and the fruiting structures in peanut are not available to these species, suggesting that this crop is a lesser quality host for southern green stink bugs than crops with fruiting structures. Therefore, an understanding of the relative performance of stink bug species among these host crop habitats is needed to clarify this aspect of their population dynamics in regional landscapes. We conducted a field plot study of the relative longevity of adult, unmated N. viridula males and females caged on peanut, cotton and soybean. Using survival estimates, we found that the proportion of the bugs surviving did not depend on the sex of the individual. After combining the sexes we found a significant difference in the proportion of adult stink bugs surviving among the crops where survival in cotton and soybean did not differ and was about twice that of peanut. Mortality per week accelerated in peanut, whereas these rates were constant in cotton and soybean. The reduced longevity of N. viridula in peanut suggests that this is a poor quality resource, and this species will likely rapidly leave peanut to colonize more preferred crops as they become available.

Technical Abstract: Recent evidence shows that southern green stink bugs use peanut as a reproductive host and adults colonize and feed in peanut, sometimes extensively. Stink bugs prefer the seeds/fruit of host plants and the fruiting structures in peanut are underground and unavailable. Therefore, it is not clear that this crop is a good quality host for southern green stink bugs. The performance of herbivorous insects is often measured through fitness-associated traits such as relative longevity and fecundity. Therefore, our objective was to determine the relative longevity of N. viridula in the field in peanut, cotton and soybean to increase our understanding of the relative quality of these resources for this stink bug species. In this study, we control for mating preference and predation and investigate effects of canopy temperature and host quality on the relative longevity of field-caged, unmated N. viridula in peanut, cotton and soybean. Sleeved cages in the cotton and soybean were white nylon mesh (0.063 cm2), 70 cm long and 30 cm d and in peanut were white nylon mesh (0.063 cm2) 30 cm long and 30 cm d with one end closed were used to confine individuals per plant and to exclude predators. Temperature sensors were placed at the midpoint of the canopy in each crop. Kaplan-Meier estimates of the survival function with all adults recorded as still alive in cotton and soybean after 27 October censored. We also calculated mortality curves (dx/lx) where dx is the number dying within age interval x to x + 1, and lx is the number surviving at the start of the age interval x, to evaluate how mortality rates change over time. The mean ± SD daily temperature in the canopy of peanut and soybean from 28 August to 7 September did not differ. The mean ± SEM temperature was 30.7 ± 0.3'C in the canopy of peanut, whereas the mean ± SEM in soybean over the same time period was 29.0 ± 0.3'. At 15 min intervals from 28 August to 7 September, the frequency of temperatures exceeding 35'C in peanut and soybean was 290 and 182, respectively. The proportion of male and female N. viridula adults surviving per crop did not differ within peanut, soybean, or cotton. When the sexes were combined, there was a significant difference in the proportion of adult stink bugs surviving among the crops. The mean longevity and 95% confidence interval in peanut in days was lower than in cotton and soybean. Peanut appears to be a less than ideal habitat in terms of canopy temperature and/or food quality for N. viridula adults. Both cotton and soybean are equally suitable food resources for N. viridula adults prior to full maturation of the plants. In diversified agroecosystems, a preponderance of peanut in the landscape would likely spatially and temporally reduce populations of N. viridula, whereas a preponderance of cotton and soybean would likely spatially and temporally increase populations of N. viridula.