Table of Contents
Introduction to Atractomorpha sp.
The study of Atractomorpha sp. (Orthoptera: Acrididae) is essential for understanding the impact of these grasshoppers on agricultural crops. Originally submitted as a PhD thesis by Narendra Pal Singh at Agra University in 1980, this research provides valuable insights into the bionomics and control of Atractomorpha sp., particularly Atractomorpha crenulata.
This species poses a threat to crops such as tobacco, paddy, cauliflower, cabbage, brinjal, and wheat, making it crucial to study its life cycle, reproductive behavior, and control strategies.
Host Plants and Feeding Behavior
Atractomorpha crenulata damages a wide variety of crops and vegetables. Key host plants include:
- Tobacco
- Paddy
- Cauliflower
- Cabbage
- Brinjal
- Wheat
Understanding host preferences is vital for targeted pest management and minimizing crop losses.
Reproductive Behavior and Oviposition
The reproductive cycle of Atractomorpha sp. involves:
- Oviposition behavior: Females dig, probe, and lay eggs in soil.
- Egg pod structure: Eggs are deposited in frothy secretions, often with a protective “plug.”
- Temperature effects: Egg-laying is optimal at 35°C, while cooler or hotter conditions reduce egg deposition.
- Soil moisture: Moist soil is preferred for oviposition, ensuring higher hatching success.
- Crowding effects: Overcrowding negatively impacts sexual maturation, fecundity, and female longevity.
Eggs undergo morphological changes during incubation, including weight and moisture absorption, which are crucial for nymph survival.
Nymphal Development and Morphology
The nymphal stage of Atractomorpha sp. is sensitive to environmental conditions and food sources:
- Number of instars: Males typically molt five times, females six.
- Wing pad development: Wing pads develop gradually, showing directional reversal in later instars.
- Morphology: Each instar has distinct physical characteristics, aiding identification.
- Crowding and diet impact: Crowding slows development and increases mortality. Diet also affects survival and growth rates, with Cauliflower, Cabbage, Brinjal, and Wheat as studied food plants.
- Cannibalism: Observed primarily in early instars, particularly under stress or food shortage.
A structured identification key helps differentiate between nymphal instars based on wing pad size and hind femur length.
Adult Morphology and Reproduction
Adult males and females display distinct physical traits. Copulation studies in controlled cages revealed:
- Behavior and duration of mating
- Effects of mating on subsequent egg-laying
- Seasonal population dynamics, with two generations per year
Understanding adult morphology and reproduction is critical for planning pest control interventions.
Seasonal Abundance and Generational Patterns
Field observations from 1976–1977 indicated:
- Two distinct generations of A. crenulata per year
- Population peaks aligned with crop growth stages
- Insights for timing insecticide application and other control measures
Control Methods and Insecticide Susceptibility
Controlling Atractomorpha sp. requires knowledge of insecticide efficacy:
- Bioassay methods: Residual film tests for nymphs, topical application for adults
- Effective insecticides: Malathion, Aldrin, Dieldrin, Gamma-BHC
- Age-related resistance: Younger nymphs are more susceptible; resistance increases with age
- Adult susceptibility: Males and females respond differently, necessitating precise dosage
Historical review and experimental findings help develop effective integrated pest management (IPM) strategies.
Conclusion
The study of Bionomics and Control of Atractomorpha sp. provides comprehensive insights into the species’ lifecycle, host preferences, developmental stages, and effective control measures. Applying these findings in the field ensures better crop protection and reduces economic losses caused by grasshopper infestations.
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