Methods in Anopheles Research - MR4

Chapter 2 : Anopheles Laboratory Biology and Culture2.3 Modifying Fecundity, Longevity and Size v2Page 3 of 6monitoring of the correct temperature in the rearing environment is necessary in order to produceconsistent-sized mosquitoes.PhotoperiodPhotoperiod is defined as the amount and schedule of light versus darkness. Even less studied thantemperature, the effect of photoperiod can dramatically affect longevity in adult mosquitoes. Manyinsectaries operate on a 12 hour day/night cycle since it is convenient for workers and similar to averageconditions. Cx. pipiens reared under a short photoperiod had smaller ovarian follicles than those rearedunder a long photoperiod (Oda and Nuorteva 1987). This was attributed by the author to the mosquitoespreparing for diapause, which can be induced by shortening the photoperiod.Reducing the photoperiod has also been found to be positively associated with an increased lifespan inAnopheles. In both An. crucians and An. quadrimaculatus, larvae reared under a short photoperiodregimen produced adults that lived longer than those reared under a long photoperiod (defined as greaterthan 15 hours of daylight) (Lanciani 1993; Lanciani and Anderson 1993).The length of photoperiod chosen, therefore, should reflect a balance between what is convenient for theinsectary staff and what is necessary to maintain a healthy colony.Adult dietThough not as critical as other effectors mentioned above, adult diet can also have an affect on thelongevity and fecundity of colonized vectors (reviewed in Foster 1995). Ae. aegypti fed sucrosesupplemented with nodihydroguariaretic acid lived longer than those reared on sucrose alone (Richie etal. 1986). An. gambiae mosquitoes fed sucrose plus blood lived longer than those fed just sucrose orblood alone. However, mosquitoes given only blood were more fecund than those fed sucrose and blood(Gary and Foster 2001). An. gambiae fed sucrose supplemented with 0.2% w/v methylparaben livedlonger than controls fed on sucrose alone (Benedict et al. 2009). Supplementation with uric and ascorbicacids lead to an overall increase in fecundity over the lifetime of a female in An. gambiae (DeJong et al2007). In general, however, sucrose solutions are suitable for regular maintenance of laboratory coloniesand care should be taken before adding supplements to the adult diet.The rearing environment, therefore, can have dramatic effects on laboratory colonies. Subtle changes inany of the above mentioned areas could result in declining fecundity or longevity and lead to colonycollapse. Optimization of some of these areas could result in a healthier colony however. It is suggestedthat testing should be done on a sample population before implementation of any changes as results mayvary between species, colonies and laboratories.ReferencesAfrane YA, Zhou G, Lawson BW, Githeko AK, Yan G (2006) Effects of microclimatic changes caused bydeforestation on the survivorship and reproductive fitness of Anopheles gambiae in western Kenyahighlands. Am J Trop Med Hyg 74:772-778Akoh JI, Aigbodion FI, Kumbak D (1992) Studies on the effect of larval diet, adult body weight, size ofblood-meal and age on the fecundity of Culex quinquefasciatus (Diptera: Culicidae). Insect Sci. Applic.13:177-181Alto BW, Juliano SA (2001) Temperature effects on the dynamics of Aedes albopictus (Diptera: Culicidae)populations in the laboratory. J Med Entomol 38:548-556Amalraj DD, Sivagnaname N, Das PK (2005) Effect of food on immature development, consumption rate,and relative growth rate of Toxorhynchites splendens (Diptera: Culicidae), a predator of containerbreeding mosquitoes. Mem Inst Oswaldo Cruz 100:893-902