Despite these promising theoretical results, current technological limitations preclude the safe use of daisy drive elements. Specifically, any recombination event that moves one or more guide RNAs within an upstream element of the chain into any downstream element will convert a linear daisy drive chain into a self-sustaining gene drive 'necklace' anticipated to spread globally (Noble et al., 2019; Scudellari, 2019).
 Other types of drives include;
i) Precision drives which directly alter genomes so that the effects of the drive are only realized in targeted organisms,
ii) Alteration drives which make specific changes, either by adding or by making     
    edits to genes,
iii) Suppression drives that reduce the number of organisms in a population, often using
      methods such as reduction of vectorial capacities,
iv) Immunising drives which prevent the spread of unwanted genes by pre-emptively altering
     genetic sequences to block the effects of precision drives (Tuna et al.,2019).
These drives can be used to add genes that cause sterility in mosquitoes and to reduce the number of mosquitoes with the capacity to transmit plasmodium. This will consequently reduce the population of vectors of the malaria parasite and hence malaria cases.  
Homing endonuclease genes (HEGs) may be designed to manipulate populations by targeting other suitable genes, such as genes to reduce lifespan, to bias sex ratios, to impede host-seeking, to block pathogen development, or to block the ability of the modified organism to act as a vector for pathogens. In mosquitoes, a synthetic version of the homing reaction was first demonstrated inA. gambiae (Windbichler et al. 2011) using a homing endonuclease from yeast. Conceptually, the simplest use for homing is to produce a population-wide gene knock-out. Modeling shows that if the knock-out phenotype is recessive and if the homing reaction is confined to the germline, then it is even possible for a homing endonuclease that causes lethality or sterility to increase in frequency in a population, potentially suppressing the population as it does so (North, and Burt 2017). Another possibility is to disrupt malaria transmission by targeting genes needed for the Plasmodium parasite to invade into, develop within, or exit out of the mosquito vector. One review lists 38 genes that when knocked-down show some reduction in oocyst number or sporozoite count (Sreenivasamurthy et al. 2013), and some of these genes may be suitable for this approach. For the homing reaction to lead to preferential inheritance of the enzyme construct, the enzyme must be expressed in the germline. Thus far, promoters used for this in Anopheles have been from the B2- tubulin gene (Catteruccia, Benton, and Crisanti 2005) and from the vasa gene (Papathanos et al., 2009). Mosquito population control using homing into female infertility genes is illustrated in Figure 3.