104 Papaya
miticides (Goka 1998). The number of miticides that can be used is further limited
because many miticides produce unacceptable phytotoxicity to papayas (Lo 2002).
Therefore, it is necessary to search for alternative approaches for controlling papaya
mite pests.
Removal of alternate host, ants and allowing natural predators and enemies to
operate in the plantation is a welcome intervention. Three specialist predators are
commonly found feeding on carmine spider mites in papaya, namely, the beetle
Stethorus siphonulus (Kapur) and two predatory mites, Phytoseiulus macropilis
Banks and Phytoseiulus persimilis. The introduced generalist predator, Nesticodes
rufipes, a sit-and-wait tangle-web building spider, very abundant on papaya leaves,
acts as the most effective predator because it can prey upon all members of the
arthropod community. M. basalis can be successfully mass produced using a micro
encapsulated artificial diet in a cost-effective manner (Lee 2003). Some insecticides,
fungicides and acaricides have also been used (Lo 2002). M. basalis may be a com-
patible, viable candidate species for use in integrated pest management programs on
papaya (Cheng et al. 2009).
9.7 Webworm
The papaya webworm (Homolapalpia dalera) also known as fruit cluster worm is
mainly a widespread pest of the developing fruit peel and papaya stem. It is usually
found near the stem amongst the flowers and fruits. The webworm causes damage by
eating the stems and the fruits of the papaya plant (Morton 1987). The holes created
by this worm allow the anthracnose fungus to enter the affected parts of the plant,
causing further damage and sunken spots on the fruit.
9.7.1 Management
The presence of webworm is evident by the presence of webs and damage can be
seen near the main stem, the region of attachment of each of the fruits produced
by the plant. Control includes hand removal and hosing off the plant with a strong
stream of water from a garden hose (Crane 2005). Damage can be prevented if 2–3
foliar sprays of dimethoate (1.0 mL/L of water) at the beginning of fruit set, or at
least at the first sign of webs are undertaken. The best method of treatment to pre-
vent webworm is by spraying the plant with malathion when the plant is about to
start producing fruits. Successful reduction of webworm can result from the use of
malathion (at 1.5 mL/L of water) or Bacillus thruingiensis (Bt).
9.8 Nematodes
Papaya suffers from many pests including plant parasitic nematodes and often crop
losses may be substantial. Papaya trees are susceptible to several nematodes, but
only two genera appear to cause economic damage in papaya cultivation. They are
reniform (Rotylenchulus reniformis) and root-knot (Meloidogyne incognita), both
of which have a worldwide distribution in papaya plantations (Perera et al. 2008).