Galerucella placida explained

Galerucella placida, is a species of leaf beetle found in South Asia, Southeast Asia and Australia.^[1] It is widely used as a bio-control agent in many rice and wheat fields to control weeds.^{[2] [3] [4]}

Description

Adult female is larger than male. Adult male is about 5.60 mm in length whereas adult female is 6.25 mm in length. Total life cycle of the beetle ranges from 21 days.

Eggs are bright yellow, with pyriform basally rounded and oval tip. Length of an egg is about 0.67 mm. The incubation period is about 3 days. There are three larval stages. First instar is yellowish and 1.26 mm in length. Initially second instar is also yellowish, but turn to blackish brown after an hour of feeding. Total length of second instar is about 2.64 mm. The third and final instar is about 5.59 mm in length and blackish brown. Total larval duration is about 13 days. Pupa is black and 4.58 mm in length.

Biology

Adult beetles are often used as biocontrol agents on the many invasive weeds such as Rumex dentatus, Polygonum glabrum and Polygonum orientale.^{[5] [6] [7]} Adults are also attracted to the leaves of the weed, Polygonum orientale.^[8]

It also feeds on aquatic weed Polygonum hydropiper. Adults feed by scraping the green tissues from the leaves. With infestation, remainingtissue also falls by producing a hole. Heavy infestation can cause all leaf tissue to removed with holes. Larval stages also scrap the green tissue to lower epidermis which produces holes of irregular shape. Heavy infestations with grubs lead leaves to dried up and become brownish.

Notes and References

1. Reid . Chris AM . 2001 . Galerucella placida Baly in Australia (Coleoptera: Chrysomelidae: Galerucinae) . 2021-09-29 . Australian Journal of Entomology . 40 . 4 . 331–334 . en . 10.1046/j.1440-6055.2001.00245.x.
2. Malik . Ujjwal . Das . Swati . Barik . Anandamay . 2018-09-01 . Biology of Galerucella placida Baly (Coleoptera: Chrysomelidae) on the Rice-Field Weed Polygonum orientale L. (Polygonaceae) . 2021-09-29 . Proceedings of the Zoological Society . 71 . 3 . 257–264 . en . 10.1007/s12595-016-0203-x. 2449911 .
3. Koner . Anamika . Das . Swati . Mobarak . Syed Husne . Barik . Anandamay . n.d. . 27 August 2021 . Short-range attraction and oviposition stimulant of a biocontrol agent, Galerucella placida Baly (Coleoptera: Chrysomelidae) toward weed leaf surface waxes . 2021-09-29 . Bulletin of Entomological Research . 112 . 2 . 204–218 . en . 10.1017/S0007485321000730. 34448446 . 237321293 .
4. Web site: Attraction of the biocontrol agent, Galerucella placida Baly (Coleoptera: Chrysomelidae) to the leaf surface alkanes of the weed, Polygonum orientale L. . 2021-09-29 . www.cabdirect.org.
5. Koner . Anamika . Debnath . Rahul . Barik . Anandamay . 2019-12-01 . Age-stage, two-sex life table and food utilization efficiencies of Galerucella placida Baly (Coleoptera: Chrysomelidae) on two Polygonaceae weeds . Journal of Asia-Pacific Entomology . 22 . 4 . 1136–1144 . en . 10.1016/j.aspen.2019.10.001. 208600575 . free .
6. Das . Swati . Malik . Ujjwal . Barik . Anandamay . December 2018 . Effect of thermal stress on antioxidant responses of the biocontrol agent Galerucella placida (Coleoptera: Chrysomelidae) . 2021-09-29 . International Journal of Tropical Insect Science . 38 . 4 . 400–409 . en . 10.1017/S1742758418000218. 92159620 .
7. Malik . Ujjwal . Karmakar . Amarnath . Barik . Anandamay . 2016-04-01 . Attraction of the potential biocontrol agent Galerucella placida (Coleoptera: Chrysomelidae) to the volatiles of Polygonum orientale (Polygonaceae) weed leaves . 2021-09-29 . Chemoecology . 26 . 2 . 45–58 . en . 10.1007/s00049-015-0206-5. 2016Checo..26...45M . 18558644 .
8. Malik . Ujjwal . Barik . Anandamay . 2015-05-04 . Free fatty acids from the weed, Polygonum orientale leaves for attraction of the potential biocontrol agent, Galerucella placida (Coleoptera: Chrysomelidae) . 2021-09-29 . Biocontrol Science and Technology . 25 . 5 . 593–607 . 10.1080/09583157.2014.1000264. 2015BioST..25..593M . 84579768 .