No abstract

The melon fruit fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) is distributed widely in temperate, tropical, and sub-tropical regions of the world. It has been reported to damage 81 host plants and is a major pest of cucurbitaceous vegetables, particularly the bitter gourd (Momordica charantia), muskmelon (Cucumis melo), snap melon (C. melo var. momordica), and snake gourd (Trichosanthes anguina). The extent of losses vary between 30 to 100%, depending on the cucurbit species and the season. Its abundance increases when the temperatures fall below 32° C, and the relative humidity ranges between 60 to 70%. It prefers to infest young, green, soft-skinned fruits. It inserts the eggs 2 to 4 mm deep in the fruit tissues, and the maggots feed inside the fruit. Pupation occurs in the soil at 0.5 to 15 cm below the soil surface. Keeping in view the importance of the pest and crop, melon fruit fly management could be done using local area management and wide area management. The melon fruit fly can successfully be managed over a local area by bagging fruits, field sanitation, protein baits, cue-lure traps, growing fruit fly-resistant genotypes, augmentation of biocontrol agents, and soft insecticides. The wide area management program involves the coordination of different characteristics of an insect eradication program (including local area options) over an entire area within a defensible perimeter, and subsequently protected against reinvasion by quarantine controls. Although, the sterile insect technique has been successfully used in wide area approaches, this approach needs to use more sophisticated and powerful technologies in eradication programs such as insect transgenesis and geographical information systems, which could be deployed over a wide area. Various other options for the management of fruit fly are also discussed in relation to their bio-efficacy and economics for effective management of this pest.

Domesticated species are impacted in unintended ways during domestication and breeding. Changes in the nature and intensity of selection impart genetic drift, reduce diversity, and increase the frequency of deleterious alleles. Such outcomes constrain our ability to expand the cultivation of crops into environments that differ from those under which domestication occurred. We address this need in chickpea, an important pulse legume, by harnessing the diversity of wild crop relatives. We document an extreme domestication-related genetic bottleneck and decipher the genetic history of wild populations. We provide evidence of ancestral adaptations for seed coat color crypsis, estimate the impact of environment on genetic structure and trait values, and demonstrate variation between wild and cultivated accessions for agronomic properties. A resource of genotyped, association mapping progeny functionally links the wild and cultivated gene pools and is an essential resource chickpea for improvement, while our methods inform collection of other wild crop progenitor species.

Host plant resistance is an important component for minimizing the losses due to the pod borer, Helicoverpa armigera, which is the most devastating pest of pigeonpea. An understanding of different morphological and biochemical components of resistance is essential for developing strategies to breed for resistance to insect pests. Therefore, we studied the morphological and biochemical components associated with expression of resistance to H. armigera in wild relatives of pigeonpea to identify accessions with a diverse combination of characteristics associated with resistance to this pest. Among the wild relatives, oviposition non-preference was an important component of resistance in Cajanus scarabaeoides, while heavy egg-laying was recorded on C. cajanifolius (ICPW 28) and Rhynchosia bracteata (ICPW 214). Accessions belonging to R. aurea, C. scarabaeoides, C. sericeus, C. acutifolius, and Flemingia bracteata showed high levels of resistance to H. armigera, while C. cajanifolius was as susceptible as the susceptible check, ICPL 87. Glandular trichomes (type A) on the calyxes and pods were associated with susceptibility to H. armigera, while the non-glandular trichomes (trichome type C and D) were associated with resistance to this insect. Expression of resistance to H. armigera was also associated with low amounts of sugars and high amounts of tannins and polyphenols.Accessions of wild relatives of pigeonpea with non-glandular trichomes (type C and D) or low densities of glandular trichomes (type A), and high amounts of polyphenols and tannins may be used in wide hybridization to develop pigeonpea cultivars with resistance to H. armigera.

Legume pod borer, Maruca (testulalis) vitrata (Geyer) is one of the major constraints in increasing the production and productivity of grain legumes in the tropics. Screening for resistance has been carried out using natural infestation, and multi-and no-choice tests under greenhouse/laborator conditions. Information is available on genotypic resistance to M. vitrata in cowpea, while such information on pigeonpea and other legumes is limited. Stem and pod wall thickness, trichomes and podding habit are associated with resistance to Mamcu. Several natural enemies have been recorded on M vitrata. Cultural practices such as intercropping, weeding, time of planting, and planting density reduce its damage in cowpea. Several insecticides have been found to be effective for controlling this insect. There is a need to generate information on insect-plant-environment interactions, screening techniques, mechanisms and diversity of resistance, genetic transformation of host plants involving Bt genes, and use of natural enemies for integrated pest management in diverse agro-ecosystems.