Morphology of the Female Reproductive System and Physiological Age-Grading of Megamelus scutellaris (Hemiptera: Delphacidae), a Biological Control Agent of Water Hyacinth

• Published in: The Florida entomologist 2017-06, Vol.100 (2), p.303-309
• Main Authors: Mattison, Elizabeth, Center, Ted D, Grodowitz, Michael J, Tipping, Phillip W
• Format: Article
• Language: English
• Subjects: Age; Animal morphology; Aquatic plants; Biological control; Delphacidae; Differentiation; Eichhornia crassipes; Epithelium; Females; Floating plants; Follicles; follicular relics; Freshwater plants; Grading; Hemiptera; Histology; Insects; Light microscopy; Megamelus scutellaris; Microscopy; Morphology; Nuclei; Nurse cells; Observations; Ovaries; ovario; ovariole; Ovarioles; ovary; Oviduct; Physiological aspects; Physiology; Pontederiaceae; R&D; reliquias foliculares; Reproductive system; Research & development; RESEARCH PAPERS; Spermatheca; Spermatophores; Tissues; Water hyacinths; Weeds; Yolk
• ISSN: 0015-4040; 1938-5102
• DOI: 10.1653/024.100.0227

The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera: Delphacidae), a biological control agent of Eichhornia crassipes (Mart.) Solms (Pontederiaceae), was examined with standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were examined with both stereo and compound microscopy. This species was typical of other delphacid planthoppers in that the reproductive system was composed of 2 ovaries with each consisting of 11 to 13 tubular ovarioles. The lateral oviduct from each ovary led to a common oviduct. Ovaries were of the telotrophic meroistic type wherein nurse cells were within the distal germarium. an enlarged sac-like bursa copulatrix opened to the common oviduct just posterior to the spermatheca. The bursa copulatrix contained globular structures that we interpreted to be spermatophores. More mature follicles contained a yolk-filled oocyte with a distinct germinal vesicle or enlarged nucleus present in the distal region of the follicle. Each oocyte was surrounded by a single layer of cells, termed the follicular epithelium, and the entire ovariole was surrounded by a thin membranous layer, the ovariole sheath. A unique structure, surrounding the most distal portion of the lateral oviduct and appearing as a loose grouping of cells that opened proximally, was visible at the base of each ovariole in reproductive females. This structure, which we termed the “collar,” did not appear to be attached to the ovarioles or the lateral oviduct tissues and has not previously been reported in other planthopper or insect species. The continuum of ovarian development was divided into 3 nulliparous and 3 parous stages based on ovariole differentiation, presence and appearance of follicular relics, and collar length, which increased linearly with increasing numbers of ovulations. Taken together, these characteristics can be used to estimate the reproductive condition and number of ovulations of this biocontrol agent.