A study on the abundance of egg production by Epilachna Chrysomellina Fabricius (Coccinellidae : Coleoptera) and its relation with temperature and relative humidity

A.I. Al-Saggaff¹, J.A. Mahyoub¹, Saleh A. Al-Digail_¹, NizamUddin Farooqui¹ and Sadeq K. N. Alhag²

¹ Faculty of Sciences, Biology Department, King AbdulAziz University, Jeddah, Saudi Arabia. ²Faculty of Sciences, Biology Department, Ibb University , Yemen.

DOI : http://dx.doi.org/http://dx.doi.org/10.13005/bbra/1041

ABSTRACT:

Epilachna chrysomellina Fabricius, order Coleopera , family Coccinellinae , is one of the phytophagous insects that feed on cucurbitacae plants . It is one of the insects that has economic effects and belongs to the genus Epilachna. It is a multi-habitat insect , distributed throughout the world. It is found in the southern region and the western coastal area of the Kingdom of Saudi Arabia due to the abundance of cucurbit plants . The insect passes through all four developmental stages , and changes in temperature and relative humidity ( RH ) affect its biological behavior mainly its reproduction and development . The insect are abundant in numbers during certain months of the year due to the favorable conditions of temperature and RH especially March , February and January , and the egg production is lowered gradually in April and May , and no egg production was noticed in June due to the gradual increase in temperature and reduction in RH . The favorable temperature and RH ranges for egg production were recorded between 23-38°C and 30-75% RH respectively . The insect show a peculiar pattern of its life cycle with atmospheric variations . The female insect lays its eggs in blocks on the lower surface of the plant leaf , with average number of eggs reaching 27.8 eggs , which hatches during 17.14 days and larval average age is 8.2 days and the pupa takes 6 days to change into adult.

KEYWORDS: Epilachna chrysomelina (F.); egg production; humidity.

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