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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Insect Control and Cotton Disease Research » Research » Publications at this Location » Publication #345066

Research Project: Detection and Biologically Based Management of Row Crop Pests Concurrent with Boll Weevil Eradication

Location: Insect Control and Cotton Disease Research

Title: Morphometrics of the Southern Green Stink Bug [Nezara viridula (L.) (Hemiptera: Pentatomidae)] Stylet Bundle

Author
item Esquivel, Jesus
item Droleskey, Robert - Bob
item Ward, Lauren - Bee Weaver, Llc
item Harvey, Roger

Submitted to: Neotropical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2018
Publication Date: 3/29/2018
Citation: Esquivel, J.F., Droleskey, R.E., Ward, L., Harvey, R.B. 2018. Morphometrics of the southern green stink bug [Nezara viridula (L.) (Hemiptera: Pentatomidae)] stylet bundle. Neotropical Entomology. doi:10.1007/s13744-018-0603-x.
DOI: https://doi.org/10.1007/s13744-018-0603-x

Interpretive Summary: The southern green stink bug is a worldwide pest of food and fiber, including cotton. In addition to causing direct damage to fruiting structures, the pest can ingest and transmit disease-causing bacterial and fungal pathogens of cotton. The insect pierces developing fruit using needle-like mouthparts which are formed by paired and modified structures that form a salivary canal (for egesting saliva to liquefy the food source) and a food canal (for ingesting liquefied food and other resources). The mouthparts originate within the head and exit the head while being surrounded by a protective sheath. It was believed that the size of the food canal could affect transmission of disease-causing pathogens. Therefore, the objective of this study was to examine food canal size and other components of the southern green stink bug stylet bundle at two locations (within the head and at the sheath outside the head) to improve our understanding of factors that may contribute to pathogen transmission. Females had larger food canals than males and food canal sizes were larger within the sheath outside of the head. For the salivary canal, size was similar between sexes and the head and at the sheath location. For both food and salivary canals, canals were larger at the sheath location compared with the head. These findings indicate the presence of a ‘funnel-effect’ with canals being wider at the more distant sheath location and the canals becoming narrower towards the head. Results indicate that size of the food canal is large enough to allow ingestion and transmission of bacterial pathogens of cotton. The food canal measurements, together with structural observations of canal shapes and the observed ‘funnel-effect’ in the food and salivary canals, improve our understanding of the stink bug needle-like mouthparts and their relationship with the insect’s internal anatomy.

Technical Abstract: The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), is a cosmopolitan pest of high-value cash crops, including cotton (Gossypium hirsutum L.; Malvales: Malvaceae). The pest can ingest and transmit disease-causing bacterial and fungal pathogens of cotton. We hypothesized that size of the food canal may contribute to selective transmission observed in previous reports. The objective of this study was to examine food canal size and other morphometrics of the southern green stink bug stylet bundle at two locations (labium and head) to improve our understanding of factors that may contribute to pathogen transmission. For the food canal, females possessed significantly larger canals than males, major axes were significantly longer than minor axes, and canal sizes were numerically higher at the labium compared with the head. For salivary canal, mean axes lengths were similar between sexes and the head and labium. For both food and salivary canals, axes lengths were longer and area was larger at the labium compared with the head. These findings indicate the presence of a ‘funnel-effect’ with canals becoming narrower proximally. Sex and location significantly affected the size of the intact stylet bundle. Results indicate the food canal was not a factor affecting previously observed selective passive transmission. Major and minor axes measurements, coupled with morphological observations of canal shapes and observed ‘funnel-effect’ in the food and salivary canals, improve our understanding of the hemipteran stylet bundle and its relationship with the insect’s internal morphology.