100 Papaya
female before she deposits her eggs. Imidacloprid (1.0 mL/3.0 L of water) is recom-
mended. It may be applied 7–10 days before the harvest. Insecticides should not be
applied more than 6 times per season (Pena and Johnson 2006). The population of
fruit fly reaching 7 individuals/trap/week during monitoring by applying 1 trap/ha is
considered to be alarming situation.
India has no fruit fly with ovipositor long enough to lay eggs inside papayas.
Home gardeners often protect the fruit from attack by covering with paper bags, but
this must be done early, soon after the flower parts have fallen, and the bags must be
replaced every 10 days or 2 weeks as the fruits develop. Fruits are harvested at the
mature green stage, and over-ripe and infested fruits should be disposed properly to
avoid further spread of fruit fly.
Control of the fly may be achieved by mechanical protection such as the use
of paper bags but it is very difficult to practice on a commercial scale. Each fruit
may be enclosed in a 1.5–2.0 kg size bag tied around the fruit stem to hold the bag.
Newspaper, one-half sheet (about 12–15 in in size), may be rolled to enclose the fruit,
then tied around the fruit stem, and also the free end. Bagging should begin when
the fruit is small, shortly after the flower parts have fallen. This method of control
is more adapted to small (1–25 plants) area than to a large (one-fourth acre or more)
area. Although bagging the fruit is the most certain method of control, it is a labou-
rious process that requires attention at regular intervals (10–14 days) to keep the
young fruit covered. Also, this procedure will injure some of the fruit unless handled
carefully. Sanitation is important in the control of the papaya fruit fly. It consists of
destroying all dropped and prematurely ripe fruits, as well as small fruits suspected
of being infested to prevent the larvae from developing into adult fruit flies (Pena and
Johnson 2006). However, this is not a feasible practice on large commercial orchards
since it is a labourious procedure, requiring regular monitoring and fruits can easily
be damaged, unless handled carefully. Feasibility of using parasitic wasps as biocon-
trol agents is under test (Nishina et al. 2000).
Papayas must be treated before export to avoid introduction of fruit flies in new
areas. Fruits picked 1/4 ripe are prewarmed in water at 43°C for about 40 min then
quickly immersed for 20 min at 48°C. This double-dipping may be replaced by irra-
diation. Fruits that had hot water treatment followed by irradiation at 75–100 krad
help to overcome the fruit fly. Use of different traps available in the market based on
sex pheromone (2-methyl-6-vinylpyrazine) produced by male to avoid use of hazard-
ous chemicals for fruit fly management (Chuman et al. 1987). Several traps, namely,
jackson trap, liquid protein bait, dry synthetic lure/liquid protein, open bottom dry
trap, yellow panel (Figure 9.3), cook and cunningham trap, champ trap, tephri trap
and steiner trap, may be used.
9.3 WHITEFLIES
Whitefly (Trialeuroides variabilis), the minute winged pest of papaya is a sucking
insect and it coats the leaves with honeydew which forms the basis for sooty mold
development. Shaking young leaves will often reveal the presence of whiteflies. It is
a major pest of the leaves of papaya trees. Damage to papaya caused by T. variabilis
is similar to the damage commonly caused by whiteflies in other crops with heavy