Comparative life history of coconut scale insect, Aspidiotus rigidus reyne (Hemiptera: Diaspididae), on coconut and mangosteen

Abstract

© 2019, International Society for Southeast Asian Agricultural Sciences. All rights reserved. The devastation of millions of coconut palms caused by outbreak infestation of the invasive Coconut Scale Insect (CSI) Aspidiotus rigidus Reyne, has posed a serious threat to the industry in the Philippines. The life history of A. rigidus on coconut and mangosteen was comparatively studied to understand the effects of host-plant species on its development, to investigate potential host-suitability factors that contributed to its outbreak infestation, and to gather baseline information on the development and characteristics of this pest. The study was conducted at the Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños. Insect size (body and scale) was not significantly different on both hosts during egg, crawler, white cap, pre-second and second instar stages, as well as during male pre-pupal, pupal and adult stages. The female third instars and adults, however, were bigger on mangosteen than on coconut. At the end of second instar, sexual differentiation was very visible wherein parthenogenic females further undergone two developmental stages: third instar and adults that feed permanently on the leaves. Males undergone three stages: pre-pupa, pupa and winged adults. Males normally have shorter life cycle and smaller bodies than the females. Developmental rate of A. rigidus before second instar was not significantly different on both hosts. However, stages approaching to insect maturity of both males and females developed faster on coconut. As a result, A. rigidus life cycle was shorter on coconut than on mangosteen. Moreover, insect fecundity was higher on coconut due to longer female longevity. More females than males were observed on mangosteen while the sex ratio was almost equal on coconut. These results suggest that coconut provides better nourishment and living conditions that support shorter life cycle and augment insect development, longevity and reproduction which are potential host-suitability factors that contributed to the outbreak. Mangosteen is an effective host-plant to rear A. rigidus pure culture as validated also by DNA sequence analysis. Information generated can be used for monitoring and timely management of the pest, in studying host-insect interaction, and in mass rearing for future studies.

Source or Periodical Title

Journal of the International Society for Southeast Asian Agricultural Sciences

ISSN

8593132

Page

123-134

Document Type

Article

Subject

Cocos nucifera, CSI, Developmental rate, Garcinia mangostana, Morphometry

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