Gonotrophic Cycle Length Research Articles

Abundance and Parity Rate of Lutzomyia cruciata (Diptera: Psychodidae) in an Endemic Focus of Localized Cutaneous Leishmaniasis in Southern Mexico

Human bait catches were carried out from 5 through 27 March 1994 in an endemic focus of cutaneous leishmaniasis in the state of Campeche, Mexico. Females of Lutzomyia cruciata (Coquillet) were dissected and 67% were parous. The number of total and parous females collected per day was analyzed by time series, but neither the gonotrophic cycle length nor survivorship could be estimated. However, a survival rate per oviposition cycle of 0.68 was estimated from the least square regression of parous on total females. Additional evidence for L. cruciata as a vector of human leishmaniasis is discussed.

Short-Term Population Dynamics of Adult Aedes dorsalis (Diptera: Culicidae) in a Northern California Tidal Marsh

Short-term changes in the age structure and abundance of the host-seeking population of Aedes dorsalis (Meigen) females were studied in a Northern California tidal marsh by daily sampling from 25 July through 17 August 1990. The calculated numbers of nulliparous and parous females per day were used to estimate parity rates and duration of the gonotrophic cycle. The numbers of females collected per day ranged from 261 to 74,443, and daily parity rates ranged from 0 to 91%. The overall parity rate was 14%. Two peaks in nulliparous female abundance on days 7 and 12 were followed 5 d later by increases in the number of parous females, indicating that two cohorts had emerged with gonotrophic cycle lengths of approximately 5 d. This is consistent with the 5-d gonotrophic cycle length estimated using time series analysis of the same data sets. Peak host-seeking activity of nulliparous females in the two cohorts occurred 16 d after two marsh systems were flooded by monthly high tides. Survivorship was estimated to be 14% per gonotrophic cycle and 67% per day, although emigration may have caused the substantial underestimation of actual survivorship.

An Assessment of the Biological Capacity of a Sacramento Valley Population of Aedes Melanimon to Vector Arboviruses

Daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for Aedes melanimon in the Sacramento Valley of California in 1987 and 1988 using mark-release-recapture (MRR) techniques and by monitoring changes in the abundance and parity rate of the native population. One objective of these studies was to determine the extent to which A. melanimon was biologically capable of serving as a horizontal arbovirus vector. Daily survivorship was estimated to be 0.90 and 0.84 in MRR studies conducted in September 1987 and August 1988, 0.89 based on changes in the parity state and abundance of the native population in August 1988 and 0.82 using summer-long parity data in 1988. Gonotrophic cycle length (GCL) was estimated to be five days in three studies. Aedes melanimon densities were estimated to be approximately 1,000,000 and 15,000 females per hectare in September 1987 and August 1988 respectively. Parous A. melanimon females were collected on each sampling occasion from April to November 1988, suggesting that A. melanimon maintained a continuous presence in the study area throughout the summer. The results of these studies suggest that A. melanimon has the potential to be an efficient horizontal vector of western equine encephalomyelitis (WEE), based on high adult survivorship, short GCL, high abundance and a continuous presence across the summer. This supports the concept of a WEE transmission cycle in the Sacramento Valley involving Ae. melanimon as an important vector. Aedes melanimon also can be an efficient horizontal vector of California encephalitis virus (CE), though the importance of horizontal transmission to the maintenance of CE virus is unclear.

Survivorship and Gonotrophic Cycle Length of Culex tarsalis (Diptera: Culicidae) Near Sheridan, Placer County, California

A population of adult Culex tarsalis Coquillett was sampled daily from 9 through 26 July 1985. Data on the abundance, trophic status, and parity were recorded. Abundance and parity data were analyzed by a time series method to estimate daily survivorship and the length of the gonotrophic cycle. Daily survivorship of blood-fed females was estimated to be 0.84 with a gonotrophic cycle length of 5 d. Daily survivorship for unfed females was estimated to be 0.86 with a gonotrophic cycle length of 7 d. The 2-d difference in gonotrophic cycle lengths was interpreted as the duration of the teneral period during which newly emerged females underwent maturation and mating before seeking hosts.

Ecology of a Semi-Isolated Population of Adult Anopheles Freeborni: Abundance, Trophic Status, Parity, Survivorship, Gonotrophic Cycle Length, and Host Selection

A population of adult Anopheles freeborni near Sheridan, CA was sampled daily during 13 August-7 September 1984. Data on abundance, trophic status, and gonotrophic age were recorded. Abundance and gonotrophic age data were analyzed to estimate daily survivorship and gonotrophic cycle length. Daily survivorship for unfed mosquitoes was estimated to be 0.72 with a gonotrophic cycle of 6 days duration. Daily survivorship for bloodfed mosquitoes was estimated to be 0.74 with a gonotrophic cycle of 4 days. The 2 day difference in gonotrophic cycles between unfed and bloodfed mosquitoes was the result of the period required for maturation and mating of teneral females. In 1986, an incage release of field-collected females estimated survivorship at 0.75 per day. Precipitin tests of 1,338 blood-engorged mosquito abdomens indicated that bovids, horses, rabbits, and canids comprised 92% of bloodmeals; no bloodmeals of human origin were detected.

Age-Related Changes in the Rate of Oviposition of Three Species of Hippelates (Diptera: Chloropidae) Eye Gnats: Experimental and Mathematical Analysis1

The mean number of eggs laid per female in cohorts of Hippelates pusio Loew, H. bishoppi Sabrosky, and H. pallipes (Loew) were 120.9, 76.7, and 59.8, respectively. Insects of the 3 species deprived of proteinaceous diet 7 h after their emergence and given only 10% sucrose solution laid only 16.7, 16.8, and 15.9 eggs per female, respectively. Shorter adult life spans and lower daily rates of egg laying contributed to the observed reduction. The daily oviposition rate increased rapidly during the first 5–7 days of cohort's age and declined gradually afterwards. Gamma distribution functions described the data. This common type of oviposition trend was shown to be an artifact of pooling the records from different females having large variance in preovipositional time. Individual records from 45 pairs of H. pusio revealed oviposition occurred in distinct gonotrophic cycles. The mean number of eggs per live female declined exponentially with the physiological age of females. The mean number of gonotrophic cycles per female was 9.93, with a mean gonotrophic cycle length of 3.23 days. An indirect probabilistic method was developed for estimating the duration of the oviposition phase of a gonotrophic cycle. The greater the number of eggs per batch, the longer the oviposition phase, with an asymptote of approximately 11 h.