Food Consumption and Growth Rates with Certain Biological Aspects of Red Palm Weevil, Rhynchophorus ferrugineus Olivier Rearing on Sugarcane Stems

Citation: Egypt. Acad. J. Biolog. Sci. (A. Entomology) Vol. 11(6)pp: 2936 (2018) Egyptian Academic Journal of Biological Sciences is the official English language journal of the Egyptian Society for Biological Sciences, Department of Entomology, Faculty of Sciences Ain Shams University. Entomology Journal publishes original research papers and reviews from any entomological discipline or from directly allied fields in ecology, behavioral biology, physiology, biochemistry, development, genetics, systematics, morphology, evolution, control of insects, arachnids, and general entomology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.


INTRODUCTION
Red palm weevil, Rhynchophorus ferrugineus (Olivier), is the most dangerous and important destructive borer to the palm trees cultivated in different Egyptian governorates.
This weevil is an invasive pest to palm trees in many countries.The origin of this pest was South East of Asia (Pakistan, India, Burma, Pengaladish and Indonesia) and spread later in the other countries (Iran, Iraq, Saudi Arabia, Emirates) and recorded for the first time in Egypt by Saleh (1992).The weevils attack the top, bottom or middle of the palm tree in any stages of growth Brand,(1917), Batt and Girgis (1996) found this pest in Sharkyia, Ismailia and Qaluobuia governorates (Egypt), also Batt (2004) found that the infestation was observed on different heights of palm trunk, however, most infestation were noticed on the lower part of about 2m. and few were apical, larvae bore tunnels in all directions, but the most run with the inner fibers of palm and upward.
The red palm weevil occurred in banana and palm trees and its larvae were occasionally found stems of sugar cane (Muir and Swezey, 1916).This weevil was commonly found damaging coconuts trees in Ceylon (Henery, 1917) in Java and Sumatra (Leefmans, 1920); in Philippines (Hernandez, 1921); in Ceylon (Huston, 1922), (De Mel, 1928), (Jepson, 1932); in India (venKatsubba Iyer, 1940), (Nirula, 1956); in Thailand (Vestal, 1956).Rahalkar et al.(1972) in India found that sugarcane stems were a good substitute for pieces of raw coconut fruit for mass rearing of the coconut pest R. ferrugineus (Olivier), also Rahalkar et al.(1978) developed on artificial diet for mass rearing of the red palm weevil R. ferrugineus pest of coconut and other palms and also of sugarcane in India, also Rahalkar et al.(1985) reared this pest on sugarcane and artificial diet.Rananavare et al. (1975) used freshly shredded sugarcane stem tissue backed in perforated boxes as a site for oviposition and a source of food for adults and larvae of R. ferrugineus weevil.Kaakeh, (2005), in United Arab Emirates, carried out mass rearing of RPW on both the natural diet and artificial diets, these diets were based on each of sugarcane, palm heart, palm leaf base, oat, potato, pineapple, oat-palm fiber sheath, oat-potato and oat-pineapple.
In Egypt, some attempts were executed to rear RPW on other non-host plants, these plants were sugarcane stems, corn stems, sweet potato tubers, carrot roots, apple fruits, dasheen, banana stems, cabbage stems, turnip tubers, table beet, potato tubers, squash fruits, colocasia and kaki fruits, the insect could complete its life cycle and produced new generations on five former plants (Hussein, 1998).The same author found that the sugarcane stems gave the shortest larval period and produced the highest number of eggs/female and highest emergence percentages, while carrot roots showed the longest larval period and gave the minimum emergence percentages, whereas the carrot roots produced the minimum number of eggs/ female.Also, Abd-EL-Azim et al.(2009)(a&b) carried out certain studies and influence of feeding with various concentrations of cane sugar on some biological aspects of red palm weevil R. ferrugineus.
The current work was carried to study certain biological aspects of RPW, R. ferrugineus, the effect of feeding with sugarcane stems on weights of adults and rate of larval growth as well as food consumption of larvae during various periods of developmental stages on sugarcane stems.

MATERIALS AND METHODS
Cocoons of red palm weevil R. ferrugineus were collected from severely infested palm trees cultivated of Tenth of Ramadan district, Sharkyia governorate during April 2018.The cocoons were placed in plastic containers and transferred to the laboratory at wood boring research department, Plant Protection Research Institute, Dokki district, Giza governorate.
The containers were covered with a muslin cloth (or perforated plastic covers) and left under laboratory conditions closed observations and daily extermination was made until the weevil emerged from cocoons.The emerged weevil was collected and sexed.
Each one couple of RPW (30 replicates) was placed on cutting (internodes) of sugarcane stem in a plastic box covered netting wire under laboratory conditions.The boxes were continuously observed and examined until egg oviposition and larvae hatched.The hatching larvae used to make laboratory rearing on sugarcane stalks (stem) to determine some aspects of larval growth such are, duration of larval instars, length and weight of larvae during different instars and amount of food consumption during the developmental stage of larvae.The continued inspection was made, the number and duration larval instars estimated by the number of exuviae and date of moulting until beginning the construction of cocoons.
To determine the amount of consumed food, 30 larvae were weighted and each larva was planted in one sugarcane cutting (about2.5cmdiameter), its weight was estimated before the cultivation of larva.Sugarcane cutting was longitudinal divided in half and gathered by elastic bands to facilitate the internal examination for larvae.The larvae were weighted at the end of each instar, the increase in larval weight was estimated of each instar.
The weight of sugarcane cutting was calculated before the cultivation of larva and at feeding end, the weight of consumed food was determined.Fifteen intact sugarcane cuttings were left under laboratory condition during the different periods of larval breeding and deficiency in moisture content was estimated.The corrected weight of food consumption was determined.
The effect of feeding on weight of adult weevil during various periods was studied, thus 25 weevils were weighed and fed on peeled sugarcane cuttings placed in plastic containers covered with perforated plastic covers, the weevils were weighed after different periods of feeding, the obtained weights of weevils at different periods were compared with the other primitive weights to determine the increase in weighted of adult weevils.
To study the acquired weight of larvae resulting from feeding, the larvae with different weights were fed on sugarcane cuttings for various periods and larvae were weighted after feeding periods, the acquired weights were estimated.The daily growth rate and percentage larval again were studied.The statistical analysis for obtained data carried out by SAS program (2001).
The following equations were used to determine some relationships between different aspects of larvae growth and food consumption, these are:  Ten larval instars were observed for RPW, reared on sugarcane stems, the larval duration until the last instar (10 th instar) was ranged 58-74 days, with a mean of 66.1 +4.60 days, the larval length of this instar ranged between 47 to 56mm, with a mean of 52 +3.03mm.
The larval weight was increasing with the increase of acquired weigh, at the last larval instar, the weight acquired recorded 0 82 g and the weight of larva was ranged 5.8 -7.4, with a mean 6.61 + 0.8 g the total increase in weight of larva recorded 6.37 g during the total growth period, which indicates that larval growth rate was 0.096 g/day.Hussein (1998) found that the mean period of larval development was 47.17days on sugarcane stems, he showed that the duration of larvae fed on trunk piece of palm varieties from 23days on Zaghlol variety to 47.88 days on ornamental dates, while the development of larvae recorded 51.50 days (on sweet potato medium), 72.17 days (on data palm medium), 85.50days (on apple medium) and 117.17 days (on carrot medium).In this respect, Rahalkar et al., (1985) mentioned that the duration from egg to prepupa of RPW was 51 -75 days when the insects reared on sugarcane stems and recorded also that the larval period lasts from 35 to 80days.
Highly significant correlations were recorded between certain biological aspects of RPW, R. ferrugineus larvae, Table (2).Values of correlation coefficient "r" were 0.987, 0.999, and 0.837 between duration of larval instars and each of length, weight and larval gain, respectively.A value of "r" was 0.973 between length and weight of larvae.3), these data indicated that all weights of adult weevils weights remain stable through the first four weeks of feeding, also the light weights of weevil (0.7-1.1g) were about stable through its life period , while the heavy weight weevils (1.2 -1.6g) appeared different changes in weevil weights, where the weights were decreased throughout the feeding period (6weeks) from 1.6g to 1.1g, 1.5-0.7 and 1.4-0.8g.The range of primitive weight varied between 0.7 to 1.6g with a mean of 1.24 + 0.266, while the last weight (after 6 weeks) were ranged 0.7 -1.3g,with a mean of 0.956 + 0.217g.The acquired weights of RPW larvae with various weights rearing on sugarcane cuttings for different periods are illustrated in Table (4) The acquired weights of RPW larvae have differed with variations in larval weights and feeding periods.The means of acquired weights for larva recorded 1.14, 0.56, 0.58 and 0.4 g at larva weights of 2, 3, 4 and 5 g levels, respectively.At the same weight levels, the means of daily growth rates were 0.045, 0.028, 0.020 and 0.021g / larva, while the percentages of larval acquired weight were 49.76, 15.65, 13.28 and 7.93% respectively.These percentages were gradually decreased with increasing of larval weight from 2 g to 5 g.

No.
Primitive weight up to (g) 4th week

Lost Moisture Content from Sugarcane Cuttings:
The lost moisture content of intact sugarcane cuttings which used as a control with the other which used for feeding to determinate the correct weight of food consumption (CWC).
Data in Table ( 5) showed the rate and weight of lost moisture content from sugarcane cuttings during rearing periods for different larval instars under laboratory conditions at the mean of 32.2°C and 58.7% RH.
Data indicated that lost moisture content from 15 cuttings was 69.6 g during 4days, while it reached 174 g during 10 days.The daily rate of lost moisture content ranged 0.35 -2.25 g (4-10days), with a mean 1.158 g for 55days with 15 sugarcane cuttings.The data also detected that the total weight of moisture content was 63.69 g during 55days while it recorded 17.37g for 15 sugarcane cuttings Larval feeding for RPW, R. ferrugineus on sugarcane stem during developmental stages from hatching until construction of adult cocoon detected the amount of sugarcane consumed by RPW larvae feeding for different periods.
Obtained data (Table , 6) indicated that consumed weight (CWC) of sugarcane stems recorded 1247.6gconsumed by 15 larvae (83.18g/ larva), this consumed amount recorded 56.59% of consumption food, with rate 3.77% larva.Daily consumption during feeding period (55days) recorded 10.37 g with rate 1.5 g/ larva, the range of larval consumption / day varied from 0.987g (recorded at the first 4days of feeding) to 1.832 g (recorded at 6 th period, representing 8 days feeding, viz.45 cumulative days).
Lost weight of Moisture content (LWMC) = weight of intact sugarcane cuttings at beginning experimentweight of sugarcane at the end of experiment.(for instar duration) = g  Daily rate of Lost moisture content= LWMC = g/day No. feeding days  The larval acquired weight (LAW) = (increasing in larval weight) = Weight of larva after feeding -Weight of larva before feeding = g  The larval acquired weight (LAW) % = Increasing weight (LAW) x 100 Primitive weight  Daily growth rate (DGR) = The larval weight again (LWG) = (g/day) Days number of feeding period  Weight of food consumption = Weight of sugarcane cutting before feeding (Introduced food)the weight after feeding = g  Correct weight of food consumption (CWC) = Weight of food consumption -Lost weight of Moisture content (LWMC) = g  Daily consumption Rate (DCR) = Corrected weight of food consumption (CWC) = (g/day) Days number of feeding period  Consumption % = Corrected weight of food consumption (CWC) x100 = Introduced food RESULTS AND DISCUSSION Certain Biological Aspects of RPW, R. ferrugineus rearing on Sugarcane Stems: Data concerning the duration of larval instars, length and weight of larvae as well as weight gain and larval growth rate for R. ferrugineus weevil reared on sugarcane cuttings are illustrated in Table (1).

Table ( 1
) Duration of larval instars, length and weight of larvae of RPW,

Table ( 2
): Correlation values between the duration of larval instars and some biological aspects of RPW R.ferrugineus larvae.

of Feeding with Sugarcane Stems on Weights of Adult Insects of RPW, R. ferrugineus:
Data on weights of red palm weevil adults fed on sugarcane stems are clarified in Table(

Table ( 3
): Weight of adult insects of RPW, R.ferrugineus feeding on sugarcane stems for different periods

Table ( 4
):The acquired weight and daily growth rate of RPW, Rhynchophorus ferrugineus larvae at different weights for various feeding on sugarcane stems.

Table ( 5
): Rate and weight of lost moisture content of sugarcane cuttings during different periods under laboratory condition of 32.2°C and 58.7% RH.

Table ( 6
): Food consumption of RPW, Rhynchophorus ferrugineus larvae fed on sugarcane during various periods of developmental stages D= Days -Cu = cumulative -CWC = Correct weight of food consumption