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United States Department of Agriculture

Agricultural Research Service

Research Project: COTTON DISEASE MANAGEMENT STRATEGIES FOR SUSTAINABLE COTTON PRODUCTION

Location: Insect Control and Cotton Disease Research Unit

Title: Characters for determining sex of late-instar Nezara viridula (L.)

Authors
item Esquivel, Jesus
item Ward, Lauren

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2014
Publication Date: March 15, 2014
Citation: Esquivel, J.F., Ward, L.A. 2014. Characters for determining sex of late-instar Nezara viridula (L.). Southwestern Entomologist. 39:187-189.

Interpretive Summary: The southern green stink bug is an economic pest of cotton and other row crops worldwide. Ongoing research requires adults of known sex and age to examine reproductive and physiological development of southern green stink bugs under different rearing conditions. However, excessive handling of newly-eclosed adults can cause mortality. The southern green stink bug has five nymphal stages (or instars) and determining sex in later instars would reduce handling of adults and alleviate mortality. The objective of this report is to describe and provide images of a key character useful in determining sex of late instar southern green stink bugs. Fifth instar females possess an indentation (or ‘slit’) at the penultimate ventral abdominal plate. Fifth instar males do not possess the slit. Dissections confirmed the relationship between the indentation, or lack thereof, and sex. Also, for females, the gradual transition to differentiation of genital plates is observed late in the stadium. More acute differentiation at the terminal plate is also observed in males late in the stadium. When fifth instars were sorted based on presence or absence of the character, assessments yielded 100% and 99% accuracy for females and males, respectively. These findings indicate the character is reliable for determining sex of fifth instar southern green stink bugs, and can be useful in future biological studies requiring minimal handling of adults.

Technical Abstract: The southern green stink bug, Nezara viridula L. (Hemiptera: Pentatomidae), is a cosmopolitan pest of cotton and other row crops. Ongoing studies require adults of known sex and age to examine reproductive and physiological development under differing biotic and abiotic conditions. However, excessive handling of teneral adults can contribute to mortality. Determining sex in late instars would minimize handling of adults and mitigate mortality. The objective of this report is to provide a description and visualization of a key character to determine sex in late instar N. viridula. Fifth instar females possess an indentation at the penultimate sternite. Fifth instar males do not possess the indentation. Dissections confirmed the correlation between the indentation, or lack thereof, and sex. Also, for females, the gradual transition to acute differentiation of genital plates is observed late in the stadium, and this differentiation yields the genital plates observed in adult females. More acute differentiation at the terminal plate is also observed in males late in the stadium. Sorting of fifth instars based on presence or absence of the character yielded 100% and 99% accuracy for females and males, respectively. These findings indicate the character is reliable for determining sex of late instar N. viridula, and can be useful in future biological studies requiring minimal handling of adults.

Last Modified: 10/20/2014
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