“Key Informant Survey” of Production, Value, Losses and ... - DfID

Table II.1. Growth indices (percentage survival from first larva to adult, divided by the
number of days elapsed for the same development) for various Bactrocera fruit flies on
various hosts (dorsalis data from Kumar and Agarwal 1998b; zonata data from Rahman et al.,
1993; cucurbitae data from Agarwal and Yazdani, 1991). Note the low scores on orange,
possibly indicating a potential niche for Ceratitis.
Bactrocera
Host Dorsalis Zonata cucurbitae
Mango 4.54 6.54
Orange 3.42 4.46
Papaya 4.84
Guava 3.58
Sapota 4.70
Smooth gourd 5.28 6.33
Long melon 6.48
Cucumber 6.74
Bottle gourd 4.79
Bitter gourd 5.96
Pointed gourd 6.51
The validity of such exercises depends on several assumptions such as the general association
between percentage survival and life-cycle duration for a given species on a range of hosts. Although
the studies cited above suggest an association, Table II.2 suggests a poor such correlation between
four varieties of mango. Laboratory studies seem to give coherent pointers to field attack severity, but
the association cannot be taken as perfect.
Table II.2. Rank ordering of four mango varieties in five parameters affecting life cycle of B.
dorsalis (Kalia and Srivastava, 1992a,b).
Variety Bangalora Malika Dashehari Amrapali
Oviposition preference 1 2 3 4
Number of oviposition punctures 1 2 3 4
Number of eggs per puncture 1 2 3 4
Life cycle speed 3 1 4 2
Percentage survival 1 2= 2= 4
Early attack in field - 1 - 2
Other basic biological information may be used to inform estimates of the relative and absolute
gravity of various pest species in various climatic zones and seasons - many good studies have
examined the basic biology of the key species such as Bactrocera dorsalis (Kumar and Agarwal,
1998c), B. zonata (Rana et al., 1992; Rahman et al., 1993) and B. cucurbitae (Koul and Bhagat,
1994a&b) including often finding a high correlation of abundance with temperature, allowing estimates
to be made of relative abundance in various zones and seasons (Patel and Patel, 1995, 1996, 1998;
Agarwal and Kumar, 1999). Temperature and diet effects have also been examined for Carpomyia
vesuviana (Dashad et al., 1999a; Sangwan and Lakra, 1992) and Gitona (Murthy and Regupathy,
1992).
Additional to the major pests are some minority species or those currently affecting only
minority crops. In Bihar Bactrocera latifrons is found in solanaceae such as Solanum melongena
(Agarwal, 1984) and, though currently only abundant in wild, marginal and medicinal species, has been
found in tomatoes (Rajendra Agricultural University, pers.comm.). B. cucurbitae is capable of
infesting brinjal, as may be seen from several specimens in the National Insect Collection at the Pusa
Institute in New Delhi, reared from brinjal in 1907. Similarly, the Gujarat Agricultural University
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