Optimization of mosquito egg production under mass rearing setting: effects of cage volume, blood meal source and adult population density for the malaria vector, Anopheles arabiensis

Abstract

Background Anopheles arabiensis is one of the major malaria vectors that put millions of people in endemic countries at risk. Mass-rearing of this mosquito is crucial for strategies that use sterile insect technique to suppress vector populations. The sterile insect technique (SIT) package for this mosquito species is being developed by the Insect Pest Control Subprogramme of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. To improve mass-rearing outcomes for An. arabiensis, the question of whether the egg production by females would be affected by the size of the adult holding cages, the source of the blood meal and the total number of pupae that could be loaded into the cages was addressed and finally the impact of adding additional pupae to the cage daily to maintain adult numbers on egg productivity assessed.MethodsMass production cages of two different volumes, two different sources of blood meal (bovine and porcine) and two different population densities (cages originally loaded with either 15,000 or 20,000 pupae) were tested and evaluated on the basis of eggs produced/cage or per female. Males and females pupae with a ratio of 1:1 were added to the cages at day 1 and 2 of pupation. The emerging adults had constant access to 5% sugar solution and blood fed via the Hemotek membrane feeding system. Eggs were collected either twice a week or daily. A generalized linear model was used to identify factors which gave significantly higher egg production.ResultsNeither cage volume nor blood meal source affected egg production per cage or per female. However, increasing population density to 20,000 pupae had a negative effect on eggs produced per cage and per female. Although high density negatively impacted egg production, adding 1000 daily additional pupae compensating for daily mortality resulted in a substantial increase in egg production. Moreover, in all tests the first and the third egg batches collected were significantly higher than others eggs batches. With the equipment and protocols described here and routinely used at the Insect Pest Control Laboratory (IPCL), it was possible to produce up to 120,000 eggs/cage/day.ConclusionThese results demonstrated that 15,000 is the optimal number of pupae to be loaded into the Anopheles Mass production cages. Under this condition, an average of 40 eggs per female was obtained for five gonotrophic cycles. However, an improvement in egg production can be achieved by daily addition, to the original 15,000 pupae, of one thousand pupae a day. Interestingly, feeding females with bovine or porcine blood using both large and small versions of the mass production cage did not affect egg productivity.

Establishment of a medium-scale mosquito facility: tests on mass production cages for Aedes albopictus (Diptera: Culicidae)

“…Artificial blood-feeding systems should be developed in any mosquito mass rearing facility. The uses of natural and artificial membranes, such as collagen sausage skins, bovine intestines (cleaned) and Parafilm, have been tested for several mosquito species [ 10 , 18 , 19 , 30 – 32 ]. The blood temperature is an important parameter for feeding responses of females [ 33 ].…”

“…A prototype of a mass production cage (MPC), based on the cage design used for Medflies in Guatemala, which has been modified to allow blood-feeding, sugar-feeding and oviposition for simplified collection of the eggs, has been tested for both Ae. albopictus [ 18 ] and Anopheles arabiensis [ 19 ]. The MPC cage was designed to reduce handling and the opening of the cages during operation such as for blood-feeding and egg collection, but the egg production of Ae.…”

“…The number of adults per cm 2 of vertical resting surface in a cage, defined as density-resting surface (DRS), is generally reported to be an important parameter for mating, feeding and longevity and a DRS value of 1.8 (1.8 cm 2 /adult) is considered suitable for mosquitoes maintenance in the laboratory [ 20 ]. Mamai et al [ 19 ] found decreased An. arabiensis egg production when overloading the cage with pupae (20,000 pupae, DRS ≈ 2.0 cm 2 /adult) compared to cages with optimized density (15,000 pupae).…”

Cost-effective larval diet mixtures for mass rearing of Anopheles arabiensis Patton (Diptera: Culicidae)

“…This result showed that a maximum egg production could be achieved in the mass rearing unit from females from all treatments. Indeed, the largest number of eggs has been found to be produced within the mass rearing cage during the first 15 days [ 32 ].…”

Criação em massa de >i<Aedes Aegypti >/i<(Diptera: Culicidae) para aplicação no controle vetorial autocida: validação de uma linhagem, otimização e planejamento

“…De forma geral, aproximadamente 10 % do total de ovos produzidos em uma criação em massa são usados para a manutenção da própria colônia matriz e o restante, para a produção de lotes dos machos para liberação (CARVALHO et al, 2014;ZHANG et al, 2018) (ZHANG et al, 2018). Entretanto, devem ser tão ou mais eficientes que as gaiolas pequenas (PVC), sem reduzir a fecundidade e a taxa de eclosão dos ovos (BALESTRINO et al, 2014;MAMAI et al, 2017;ZHANG et al, 2018). Portanto, quando eficientes, são estratégicas para o aprimoramento de uma criação em massa e contribuem para a redução dos custos operacionais.…”