Black and White: Modified Black-Bottom Containers for Mass Egg Collection of Wolbachia-Infected Aedes aegypti

Efficient egg collection is important for large-scale mosquito rearing, but it presents logistical challenges and often yields suboptimal egg numbers in mass rearing cages. Furthermore, uneven distribution of eggs on oviposition substrates can lead to higher fatality of the first instar (L1) larvae among overlapping/stacked eggs. Previous studies showed that incorporating darker hues into oviposition pots (ovipots) improves egg collection, yet few discussed designs of containers for use in mass rearing cages. Using a no-choice experimental setup, the number of eggs collected per female was determined in cages of Wolbachia-infected Aedes aegypti mosquitoes provided with different ovipots. The percentage of dead larvae among the stacked eggs was also determined. Based on this information, different prototypes of a more efficient, larger ovipot were evaluated in mass rearing cages. A black-bottom container with white crepe paper collected the most eggs per blood-fed female by promoting higher oviposition rates. A significantly lower percentage (0.31%) of dead L1 larvae were found among relatively sparser eggs compared to 0.96% among stacked eggs. A larger, black-bottom ovipot with oviposition papers positioned at the center of the container, demonstrated suitability for use in mass rearing cages, promoting better egg distribution and yield.