Ann. Entomol., 31(1) : 21-29 (2013) ISSN 0970-3721 CUTWORMS OF EGYPT 3-THE BIOLOGY OF AGROTIS SPINIFERA (HUBNER) (NOCTUIDAE : LEPIDOPTERA) by El-Sherif , S.I. and S.A. Abd El–Rahman* Dept. of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, ORMAN, GIZA, EGYPT. [email protected] Abstract In Egypt, cutworms from family Noctuidae and order Lepidoptera are serious polyphagous pests. Agrotis ipsilon (Hufn.) is the most abundant cutworm species followed by Agrotis spinifera (Hubner). Locally, plenty of research has been done on A.ipsilon while very little is known about A.spinifera. This article aimed at adding new contributions to the knowledge on the biology of A.spinifera. Egyptian clover (Trifolium alexandrenum L.) was the most favorable host plant for rearing the larvae of the pest, and a technique to maintain a laboratory stock culture of it is described. Under laboratory conditions, A. spinifera had 3 complete and a 4th. partial overlapping annual generations. The 1st. (winter) generation took place from early-November until early-March, and lasted for 102 -113 days. The 2nd. (early spring) generation occurred between mid-February and late- April, and lasted for 45 – 59 days. The 3rd. (late spring) generation elapsed the period from mid-April until mid–June, and lasted for 56 – 62 days. The partial 4th. (summer) generation occurred between early-June and late-September, with a mean duration of about 88 days. The durations of the egg , larval ( with 6 instars) , female pupal. male pupal, female adult and male adult stages were 4 – 15, 27 - 82, 8 – 17, 10 -19, 2 – 12 and 2 – 13 days, respectively. Pre-oviposition, oviposition and post-oviposition periods of mated female moths ranged 1 – 7, 1 – 10 and 0 – 2 days, respectively. Egg-laying capacity ranged 0 – 1421 eggs / mated female. The total life-cycle was completed in 53 – 113 days in female individuals and 53 – 111 days in male individuals. Keywords : Agrotis spinifera (Hubner) , Biology, Annual generations, Egypt. Introduction Rahman (2012 a) ascertained that there are - at Cutworms from family Noctuidae and order least- seven cutworm species belonging to two Lepidoptera are a group of economically genera from the tribe Agrotini. According to El- important polyphagous insect pests threatening Sherif and Abd El–Rahman (2012 b) the most the seedlings of a wide variety of agricultural abundant cutworm species in Egypt are the black crops and many weeds in Egypt. The early larval (or greasy) cutworm Agrotis ipsilon (Hufn.) (= instars of cutworms feed on plant foliage while A.ypsilon Rott.) followed by Agrotis spinifera older instars bite into young plants from (Hubner) (= A. biconica Hbm) while the other underneath at soil level or slightly above it species are of occasional to rare or very rare causing serious damage. Literature refers to a occurrence. noticeable discrepancy in the number of cutworm The majority of investigations on cutworms species in Egypt. However, the works of Nasr in Egypt concentrated on A.ipsilon being the and Nazmi (1975) and El-Sherif and Abd El– most serious and destructive among this group Received on : 29/08/2012 Accepted on : 09/03/2013 *Cutworms Research Division, Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt. 22 El-Sherif, S.I. and S.A. Abd El–Rahman of pests. Meanwhile, very little has been type light trap (fitted with a 125 Watt U.V. bulb) published on the local other cutworm species, was operated in an open field from dusk to dawn especially in respect of their biology . To contribute for about two month before this investigation to such a gap in the available information on begins. The killing receptacle (jar) of the trap was cutworms in Egypt, the current study was aimed replaced by an empty one to receive attracted with the objective of adding new knowledge on insects and, in the meantime, keeps them alive. the various aspects of the biology and annual The receptacle jar was also provided with soft generations of A.spinifera which ranks - in cloth strips to keep the scales of the captured economic importance – next to A.ipsilon. El- insects intact and, hence, facilitate their proper Sherif and Abd El–Rahman (2012 b) mentioned identification visually. Every morning, the whole that, in Egypt, A. ipsilon formed over 86% of trap catch of alive insects was anaesthetized ( the whole cutworms’ moth population in light by introducing a small piece of cotton wool lightly trap catches while A. spinifera formed less than soaked in ether or chloroform into the jar until 10% of it. As a matter of fact, few authors the insects in it calmed down and became almost reported on the biology and annual generations motionless). At this point, the jar was carefully of A.spinifera ( Rivnay and Yathom ,1964 in emptied quickly on a white sheet of paper, and Palestine, Singh, 1986 and Gautam and Trishla the anaesthetized insects fetched – with the aid Gupta,1994 in India, Hammad and El- Minshawy of a fine camel-hair brush- for the presence of ,1966, Ghanim et al., 1979 and Abu-Hashish et adult moths of A.spinifera, which were al.,1988 in Egypt). Also, scattered hints on the immediately individually introduced into 1x3 biology of A. spinifera in Egypt were given by inches glass vials covered with muslin fitted in Willcocks and Bahgat (1937), Abd El–Rahman place with rubber band. Separated moths were (1984), El-Mergawy et al. (2003) and Fediere et left in the vials until they recovered from al. (2003). anesthesia and regained normal movement then were sexed according to the description given Material and Methods by El-Sherif and Abd El–Rahman (2012 a). 1- Host plant Healthy active moths were selected and In a pilot laboratory test, the leaves of 12 introduced into oviposition cages at a rate of 1 host plants (lettuce, cabbage, potatoes, alfalfa, pair (1female & 1 male) /cage .The cage cotton, maize, wheat, Egyptian clover, castor oil, consisted of a 1 lb chimney glass with its lower bindweed, fenugreek and chick pea) were tested opening resting on the bottom of a Petri-dish lined for their suitability to feeding the larvae of with black paper and its upper opening covered A.spinifera. Larvae of different instars were hardly with a piece of thick black cloth. The internal collected from numerous cutworm-infested fields walls of the chimney glass were also painted in under different crops at several scattered areas black to secure the darkness necessary to of the country. Collected larvae were individually enhance oviposition (Abd El–Rahman, 1984). kept in plastic containers of suitable size to avoid Every cage was provided with a small piece of cannibalism and provided with leaves of the cotton wool saturated with 20% sucrose solution tested host plants. Observations indicated that for feeding the moths and 2-3 cuttings of clover the larvae were most healthy and achieved stems with leaves on them to serve as maximum growth when they were reared on the oviposition sites. Oviposition cages were fresh leaves and stems of Egyptian clover examined daily to collect deposited eggs, renew (Trifolium alexandrinum L.). Accordingly, a stock clover cuttings and replace the feeding cotton culture of A.spinifera was maintained on wool. Egyptian clover leaves and stem-cuttings. The stock culture was started with groups of eggs collected from the oviposition cages and 2- Stock culture kept in Petri-dishes until hatching. Thereafter, To establish the stock culture, a Robinson groups of 10 – 15 newly hatched larvae were Ann. Entomol., 31(1) : 21-29 (2013) Cutworms of egypt 23 introduced into clean 1 liter rearing glass jars 3- Biology and annual generations covered with thick toilet paper to prevent The study of the biology and annual escapes. Every jar was provided with a suitable generations of A.spinifera was carried out under quantity of clover stems and leaves as larval the prevailing laboratory conditions throughout food. Jars were examined twice daily to replace nearly a complete year extending from the month them with new sterilized clean ones, exclude the of November until the month of next September. bodies of dead larvae and add new food supply. The laboratory temperature and relative humidity Such procedure continued until the larvae were recorded with a thermohygrograph and reached 4th. Instar when some of them began to illumination period was controlled by an electric show the cannibalistic behavior. At this stage, it time-switch. The daily means of temperature and became necessary to keep every larva relative humidity for the period extending from individually isolated in a separate space. the beginning till the end of every generation and Therefore, larvae were transferred to plastic ice- each developmental stage in every generation cube trays at a rate of one larva / each of the were worked out. cells of the tray. Ice-cube cells were continuously The 1st. generation started with newly-laid provided with fresh clover leaves until the larvae eggs obtained from the stock culture at were about to pupate. As a frequent observation intermittent intervals throughout the month of , the grown larvae (5th. & 6th. Instars) usually November. Eggs were kept in sterilized Petri- remained in their isolated cells as long as they dishes until hatching and the incubation period had sufficient food and it was unnecessary to recorded. One hundred newly-hatched larvae cover the ice-cube trays. Occasionally, however, were individually introduced into 1x3 inches glass some larvae tended to leave their cells and, in vials each provided with few fresh clover leaves such a case, the trays were covered with thin and tightly covered with plastic covers. To ensure plastic sheets that stick firmly to the outer rims sufficient aeration in the vials, several minute of the tray.