EXERCISE 6: Identification and Classification of Crop Pests

• Pests


  Biotic components of the agroecosystems that affect crop production
• Types of crop pests


  • Invertebrate (insects, mites, mollusks)
  • Vertebrate animals (rodents, birds, bats, monkeys, humans)
  • Weeds (broadleaf, gass, sedge)
  • Pathogens (bacteria, fungi, virus, mycoplasma)
• Pests directly damage the leaves, stems, roots, and branches of crops and impair physiological processes such as photosynthesis, absorption of water and nutrients, translocation of assimilates, and transpiration
• Pests compete with crops for resources needed for establishment and growth such as water, nutrients, sunlight, and CO2 or thus affecting the quantity and quality of grains, fruits or produce
• Pests can completely kill seedlings of crops
• Invertebrate pests

  • Insect pests
  • Mites
  • Mollusks
• Vertebrate pests


  • Rodents
  • Birds
• Pathogens

  • Bacteria
  • Fungi
  • Virus
  • Mycoplasma
• Weeds


  • Broadleaf
  • Grass
  • Sedge
• Pests' nature of damage

  • Directly damage the different plant organs
  • Impair physiological processes such as photosynthesis, absorption of water and nutrients, translocation of assimilates and transpiration
  • Directly or indirectly compete for the requisites of the hosts such as water, nutrients, sunlight and CO2
  • Completely kill the seedlings
  • Negatively affect the quality and quantity of produce
• Insects


  • Belong to Class Insecta/Hexapoda (six-legged) in the Phylum Arthropoda
  • Have 3 body regions: head, thorax, abdomen
  • Have three pairs of legs
  • Have one pair of antennae (rarely no antennae)
  • Wings either present or absent

  
• Types of insect damage


  • Defoliators chew leaves or stems
  • Borers bore into leaves, stems, tubers
  • Leaf miners tunnel in epidermal layer
  • Root feeders chew on roots
• Insect mouthparts

  • Mandibulate (feeding mainly on solid food)
  • Haustellate (feeding mainly on liquid food)
• Rice Insect Pests 


  Brown planthopper - Nilaparvata lugens

  Yellow Rice Stem Borer - Scirpophaga incertulas

  Black Armyworm - Spodoptera exempta

  Rice bug - Leptocorisa oratorius

  Rice weevil - Sitophilus oryzae
• Corn Insect Pests 


  Asiatic Corn Borer - Ostrinia furnacalis

  Corn Seedling Maggot - Antherigona oryzae

  Maize Weevil - Sitophilus zeamais
• Coconut Insect Pests


  Coconut Scale Insect - Aspidiotus rigidus
• Banana Insect Pests


  Banana corm weevil - Cosmopolitus sordidus
• Mungbean Insect Pest


  Black bean aphid - Aphis craccivora
• Fruits and Vegetables Insect Crops

  Fruitfly of mango - Bactrocera dorsalis

  Fruitfly of cucurbits - Daucus cucurbitae

  Fruit and shoot borer of eggplant - Leucinodes orbonalis

  Diamond backmoth in crucifers - Plutella xylostella
• Mites


  belong to class Arachnida
• two body regions of mites: gnathosoma and idiosoma
• Mites - scrape off the leaf surface and sucks up the fluid from the top layer of cells and cause the leaf to turn to a silvery color
• Mollusks

  • direct feeding damage by attacking rice seedlings
  • golden apple snail (Pomacea canaliculata)
• Rodents

  • attack rice, sugarcane, fruits, vegetbale and root crops
  • belong to class Mammalia
• Birds

  • chew rice grains in the milky stage causing whitened or unfilled panicles
  • Philippine maya
• Pathogen - living agent that causes diseases in plants
• Disease - abnormal change in structure or function maneifested in form of symptoms
• Plant Disease Diagnosis - identification of diseases based on symptoms and signs
• Symptoms - the signs or indications of a disease or condition.
• Signs - pathogen found associated on a host plant
• Local symptoms - express in a limited areas of tissues of the hosts
• Systemic symptoms - expressed as the reaction of greater part of all plant parts
• Fungi - small eukaryotic organisms that have filamentous vegetative body called mycelium and reproduce by means of spores
• Fungal disease signs

  • leaf rust
  • stem rust
  • sclerotinia
  • powdery mildew
• Fungal disease symptoms

  • birds-eye spot
  • damping off of seedlings
  • leaf spot
  • chlorosis
  • necrosis
• Bacteria - prokaryotic organism possessing unit membrane and cell wall that reproduce through binary fission
• Bacterial disease symptoms

  • leaf spot
  • fruit spot
  • canker
  • gall
  • blighting
• Bacterial Diseases

  • Bacterial blight of rice (Xanthomonas oryzae)
  • Bacterial leaf strike of rice (Xanthomonas oryzae)
  • Bacterial soft rot of vegetables (Pectobacterium carotovorum)
  • Bacterial wilt of tomato (Ralstonia solanacearum)
  • Bacterial spot of tomato (Xanthomonas campestris)
• Fungal Diseases

  • Black pod rot in cacao (Phytophthora plamivora)
  • Downy mildew of corn (Peronosclerospora philippinensis)
  • Leaf blight of corn (Helminthosporium maydis)
  • Corn rust (Puccinia graminis)
  • Banana sigatoka
• Virus - ultramicroscopic obligate parasites consisting of nucleic acid core and protein coat