The Blister Beetle Meloe Proscarabaeus (Coleoptera: Meloidae) a Dangerous Pest Threatens Field Crops in New Valley Governorate, Egypt

Egypt. J. Plant Prot. Res. Inst. (2020), 3 (1): 73 - 82

Egyptian Journal of Plant Protection Research Institute

www.ejppri.eg.net

The blister beetle Meloe proscarabaeus (Coleoptera: Meloidae) a dangerous pest threatens field crops in New Valley Governorate, Egypt

Wael, E. A. El-Sheikh 1 and Ahmed, I. El-Tokhy 2 1Department of Plant Protection, Faculty of Agriculture, Beni-Suef University, Egypt, Beni-Suef 62511, Egypt. 2Department of Plant Protection, Faculty of Agriculture, New Valley University, Egypt. ARTICLE INFO Abstract: Article History The blister beetle, Meloe proscarabaeus L. Received: 16/ 1 / 2020 (Coleoptera: Meloidae) was recorded for the first time as a Accepted: 27 / 2 /2020 serious insect pest attacking wheat (Triticum aestivum), Keywords faba bean , peas, alfalfa, onion and wild weeds in El- Farafra Oasis, Western Desert, Egypt. Beetles feed on Blister beetle, Meloe foliage and flowers of injured plants causing defoliation proscarabaeus, population and crop loss. The population dynamics and bionomic dynamics, wheat , El- observations in the wheat fields of M. proscarabaeus were Farafra Oasis and Egypt. studied during two successive seasons (2016/2017 and 2017/2018) in Wheat fields. The pest develops one generation per year. The beetle continued to appear during the first week of December to the first week of April, with the peak of adults at the first week of February. Beetles secrete a cantharidin fluid, a potent blistering agent which burns plant leaves and flowers and at the same time, it is strong poison to all livestock and domestic animals feeding on contaminated plants. The present work shed light on food plants, symptoms of infested crops, adult activity, environmental effects, and sexual behavior of the blister beetle M. proscarabaeus under the circumstances of El- Farafra Oasis. Introduction Blister beetles or oil beetles are regions of the western United States. In members of the family Meloidae Egypt, Alfieri (1976) recorded 9 species (Coleoptera). This family includes over belonging to family Meloidae collected 300 species in the United States (Selander from different desert localities vicinity to and Bouseman, 1960; Stebnicka, 1987; Cairo. Most adults eat only floral parts, Bologna, 1988 and Odegaard and but some, particularly those of Epicuta Ligaard, 2000). The genus Epicuta is the spp., eat leaves. El-Sheikh (2007) largest and contains many species that observed that beetles belonging to Meloe concern forage producers in semi - arid proscarabaeus L. (Coleoptera: Meloidae)

El-Sheikh and El-Tokhy, 2020 eat leaves and flowers of faba bean reclamation of many thousand hectares. plants. A few adults are noctural; most Many different field crops have grown are diurnal or show no distinct diel cycle successfully with high yields, especially (Selander and Fasulo, 2000 and Bologna winter Wheat and legume crops. El- and pinto, 2002). However, except for Farafra Oasis is characterized by a very first instar larvae (triunglins) frequenting hot desert climate, temperatures during flowers or clinging to adult bees. So far the summer season reach 60 degrees as known, all larvae are predators. Larvae Celsius and decrease significantly in of most genera enter the nests of wild some months during the winter to one bees, where they consume both immature degree Celsius. Rain is rare and the bees and the provisions of one or more average relative humidity is 30-45%. One cells ((Lückmann and Kuhlman, 1997; of the most common cultivated crops Klausintzer and Rauch, 2000 and there is Wheat (Triticum aestivum ), its Stebnicka, 1987). cultivated area amounts approximately In Central Europe, several types of 6500 feddans, however, and this crop is the Meloidae family have become rare in threatened by the attack of the blister some regions. The fertility of Meloidae beetle, M. proscarabaeus L., the most has reached 90% the number of eggs per serious pest (El-Sheikh, 2007). female is 9500 eggs inside a trench dug 2.Beetles sampling: by the female (Lückmann, 2001 and Field observations on the blister Bologna and Pinto, 2001). Blister beetles beetle, M. proscarabaeus L. ( Coleoptera produce cantharidin, which is toxic to : Meloidae ) including beetle emergence , people and animals (Ward, 1985). For distribution, sexual behavior, feeding centuries, cantharidin was prescribed as a habits, and dial activity were carried out cure for variety of animals. Spanshfly or throughout the years 2016 /2017 and cantharis, an oreparation of dried beetles, 2017 / 2018 in El-Farafra Oasis, western was thought to cure gout, carbuncles, desert of Egypt. Observations rheumatism and many other medical commenced from mid-November till late disorders, in addition to its use as an April; activity period of beetles in the aphrodisiac (Kinney et al., 1998). field at about 10 am. The field The present article sheds light on the observations included the study of occurrence of the blister beetle M. emergence period, population ecology of proscarabaeus, population dynamics and the beetles at different times and sexual bionomic observations in the Wheat behavior. This was carried out in two fields and other legume crops as being ways: (a) Oviposition sites of the newly recorded for the first time in El-Farafra emerged female beetles were recognized Oasis. in the field and marked; these were Materials and methods separated into eight groups, three sites 1.Study area: each, according to date of egg laying. El-Farafra Oasis lies in the Each site contained one egg mass (4000 – western desert, south part of Egypt, 4500 eggs). Wire – wooden cages, 35 x located at latitude and longitude 50 x 50 cm each, were fixed on each site. (26°49′23.3″N 27°46′33.3″E), belonging Daily observations of cages were to New Valley Governorate; it is 600 km continued until beetle's emergence. The far from Giza. El-Farafra Oasis is rich number emerged beetle of each group with submersible water which facilitates was recorded as well as time of

Egypt. J. Plant Prot. Res. Inst. (2020), 3 (1): 73- 82 emergence and related environmental To analyze the association prevailing temperature. (b) In El-Farafra between agro-climatic factors prevailing as a whole adult M. proscarabaeus have in El-Farafra Oasis and population been recognized in the months December, dynamic of the blister beetle adults January, February, March and April. through activity time. Weekly number of Freshly emerged beetles were marked collected beetles was plotted against the with a color code (Whitehead, 1991). considered agro-climatic factors to This proved that emergence took place in establish the relationships between these synchronous waves during November factors and adult density using correlation and December. Similarly, number of and partial regression analysis (α) (Fisher emerged beetles was correlated with et al., 1943). prevailing temperature of the Results and discussion environment. Population dynamics of 1. Food and feeding habits: newly emerged beetles and adult Adult beetles M. proscarabaeus abundance in relation to prevailing were feeding on wheat leaves, stem, and temperature and relative humidity were spikes, where the beetles are observed conducted in Wheat fields during two moving from places where they were successive seasons 2016 / 17 and 2017 / located during their summer (aestivation) 18. Density of beetles was assessed as dorms towards wheat fields and adults direct count in 100 m of Wheat plants. attack in swarms where they disperse and Counting of beetles was carried out in the start feeding for up to 80 days. El-Sheikh different directions (north, south, east, (2007) explained the blister beetle insect and west) of the field at weekly intervals pest infesting crops of beans, alfalfa, (El-Sheikh, 2019). onions and wild herbs, which is a pest on The micro-climatic conditions of flowers, sugar beets and cabbage in the air as temperature and relative Europe (Ozbeck and Szaloki, 1998; humidity were also measured. The life – Stebnicka, 1987 and Selander and Fasulo, span and the fecundity of adult were 2000). Date of planting wheat in Farafra determined by confinement freshly Oasis From mid-November, beetles begin emerged beetles in pairs (female & male) to appear when wheat is in the seedling on Wheat plants inside wire - wooden stage about 10-15 days after planting cages (35 x 50 x 50 cm) fixed in the field. these young plants are the most Daily observations on sexual behavior, preferable food for Blister beetles feeding habits periodicity and egg laying (Figure, 1). were started from the first week of The newly emerged blister beetle December (first beetle emergence) to are distinguished by strong mandibles mid-February (last date of beetle and long legs that help them climb the emergence). Data were derived from 24 plant, attack wheat seedlings, and feed on field cages. leaves and stem, causing completely 3.Meteorological data: destroy the whole plants. At risk, the M. Daily maximum & minimum air proscarabaeus secrete a yellow liquid temperatures (˚C), air relative humidity from coxal and antennal joints (Figure, (%) were supplied by the Meteorological 1). These blister beetles are used to Station at New Valley Governorate. defend themselves, and this liquid causes 4.Statistical analysis: the leaves to burn and turn brown, eventually the plant dies. Plants that are

El-Sheikh and El-Tokhy, 2020 under severe attack by blister beetle fail adult density was 115 and 130 beetles / to produce flowers and spikes and 100 plants in 2016 and 2017 (Tables, 1 consequently the crop is completely lost. and 2). Turco (2003) recorded a female M. With the decrease in air proscarabaeus grazing on Ranuchus sp. temperatures and the increase in relative in Cornwall. Feeding of beetles occurs humidity, the number of blister beetle during the daylight and continues until increased gradually, with the average sunset, and we notice the most general monthly catch rate of about 39-36 % number of beetles on the field side closest during the months of January and to the irrigation canals. Ward (1985) February in 2016 /17. Adult activity reported that blister beetles feed on plant decreased significantly, as the average materials, particularly flowers of such catch rate in March and April was 8-1% plants as alfalfa, careless weed , peanuts, of blister beetle in 2017/18 (Tables, 1 and soybeans and many other species. As 2). The study showed that the period shown by Pinto and Selander (1970), the from December to February was the beetles were not recorded on the wheat highest number of beetles. The weather crop. It appears that the wheat crop is not conditions that prevailed during the two registered as food for beetles and thus seasons of the study did not differ becomes food plant as a diet of M. significantly, accordingly, the variation of proscarabaeus the first record in Egypt. M. proscarabaeus population for adults 2. Seasonal activity of beetles : mean in 2016/17 (44.8 beetles) and In EL-Farafra Oasis, all adult 2017/18 (53.05 beetles). However, blister beetle, M. proscarabaeus were climate factors played a large role in the recognized in December, January, number of beetles in significantly February, March and April in 2016 and reducing or increasing the population of 2017. We noticed the emergence and beetles, and the relationship of dispersion of newly emerging beetles in temperature was a direct and the relative the fields of wheat. The weekly humidity is an inverse relationship during assessment of the density of adult beetles the two seasons (Tables, 1 and 2). Results in different parts of the wheat field from the weekly follow-up of the insect indicates that November 3th is the first population reveal the persistence of adult activity and April 2th as the last behavior in adults blister beetle M. (Table, 1). Adults emerged from larvae proscarabaeus under EL-Farafra and has that were in the soil and then evolution only one generation per year. Whitehead into a pupa stage and then an adult insect (1991) reported that an adult from M. in first week of November with a few rugosus was identified in October and ranged between 12 and 15 beetles / 100 November and that the apparition bean plants It was average air occurred in simultaneous waves during temperatures 25.3 - 26 °C and relative September and October. However, the humidity 51.5 - 60 % , in 2016 and 2017 frequency of the appearance of adults M. respectively (Tables, 1 and 2). The rugosus occurs in the same period as M. population density of the blister beetle proscarabaeus three waves of one stage gradually increased with a distinct peak have been observed for the present in the first week of February; the average species.

Egypt. J. Plant Prot. Res. Inst. (2020), 3 (1): 73- 82

Table (1): Mean numbers of the blister beetle Meloe proscarabaeus adult emerged in EL-Farafra Oasis 2016, 2017 in relation to air temperatures and relative humidity.

Mean no. of Climatic factors beetles /100 % Number of Inspection date plants Mean air temp. Relative monthly beetles oC humidity %

Dec. 3/2016 12 25.3 51.5

10/2016 17 23.1 66.5

17/2016 20 24.0 53.5 14% b 24/2016 26 22.5 46

31/2016 34 21.2 58.6

Jan. 7/2017 56 19.6 61.3

14/2017 73 20.1 67.5 39% a 21/2017 89 19.7 71.5

28/2017 101 18.2 57.5

Feb. 4/2017 115 17.0 58

11/2017 75 16.8 66 36% ab 18/2017 61 18.6 55.3

25/2017 40 20.3 45.2

March 5/2017 31 22.9 39.4

12/2017 28 24.4 37 10% c 19/2017 17 26.5 39

26/2017 8 30.7 32

April 2/2017 5 35.4 30 1% d

Total 808 100%

Mean 44.8 25%

El-Sheikh and El-Tokhy, 2020

Table (2): Mean numbers of the blister beetle Meloe proscarabaeus adult emerged in EL-Farafra Oasis 2017, 2018 in relation to air temperatures and relative humidity. Mean no. of beetles Climatic factors % Number of Inspection date /100 plants Mean air tmp. oC Relative humidity % monthly beetles Dec. 5/2017 15 26 60 12/2017 19 24.3 58 19/2017 25 25.1 56.2 10% b 27/2017 31 23.2 52 Jan. 3/2018 40 20.6 59 10/2018 55 18.8 63.2 17/2018 69 20.7 64.3 42% a 24/2018 95 18.6 70.4 31/2018 113 17.5 65 Feb. 7/2018 130 16 60 14/2018 95 15.8 58 39% ab 21/2018 75 16.4 52 28/2018 53 18.9 44 March 7/2018 30 20 42.1 14/2018 18 23.5 36.5 8% c 21/2018 10 25.7 38.2 28/2018 7 28.9 32.4 April 5/2018 5 34.7 31 1% d Total 955 100% Mean 53.05 25% 3. Mating: Females are taller and larger in Several pairs of adult's blister size than males; females pull their beetle were observed in intercourse abdominal segments (telescope during the periodic inspection of affected movement) to cope male's abdominal wheat fields, copulation occurred during end. Male abdominal tip flexed below the daylight. Blister beetle, M. abdominal tip of the female, the highly proscarabaeus showed evidence of chitinized male genitalia protruding and a mating that reached sexual maturity (50 great part of it was inside the female days post emergence). Certainly those body, widely opening the female genitalia males are attracted to females by sex aperture for the entrance of the apical pheromone emitted by the female. The fleshy part of aedeagus. After this, the male begins searching for the female in male rolled up to the opposite direction the early morning and when they meet, (tail to tail position) and mating was courtship may start. Primarily, males carried out see Figure (1). The maximum touch the female partner's antennae that period of the act of copulation lasted for have faced their side and when the female about one hour. When the male and shows a response, the male touches her female are disturbed during copulation, abdomen by its antennae. Repeated they soon separate from one another. touches may occur until the female stops Selander and Pinto (1967) describes quietly, the courtship period lasts 30 sexual behavior in the Meloidae family, minutes. The male jumped on the female as it is very similar in sexual behavior. side quickly and held the female by the The male and female meet in the early front legs in the thorax area and the back morning and start feeding, Then the male legs in the female's abdominal area begins to flirt with the female, and its (Figure, 1). duration varies from one type to the next,

Egypt. J. Plant Prot. Res. Inst. (2020), 3 (1): 73- 82 after the female’s approval, copulation Field and laboratory research has takes place. Turco et al. (2003) explain shown that adult beetles, M. that the sexual behavior of the beetle proscarabaeus exudates a yellow liquid includes strange stages, when the male in abundance from the joints of their legs meets the female, the female controls the and Antenna. This fluid is often excreted male through a sexual pheromone. by reflexive bleeding when an adult 4. Oviposition habits: beetles are at risk see Fig. (1). This It was noticed that the female phenomenon is most common in most blister beetles after mating begin to type's species of Meloid beetles (Ward search for the preferred location for 1985; Edwards et al., 1989 and ovulating and she spent two hours Whitehead 1991). Like other species of searching for the right place. These blister beetle, M. proscarabaeus contain a blister beetle, M. proscarabaeus prefer large amount of oily, yellow hemolymph sandy soil and choose elevated sites from that you exude on annoyance. This fluid the field near the irrigation canals. has been identified as a cantharidin (a Females begin to prepare the egg bicyclic terpenoid C10 H12 O4). It is chamber hole, which is 5 cm in diameter found in hemolymph and gonads of and 6 cm deep in the border strip of the beetles. Lytta respiratory (Meloidae) field, and used mandibles, fore and hind contains more cantharidin than any other legs in excavating the oviposition member of the family; cantharidin is chamber. After finishing the ovary found mainly in elytra but it has also chamber preparation, it will settle inside been shown to exist in the genitalia and and the head and the rest of the body the hemolymph (Bohac and Winkler, appear inside the chamber, oviposition 1964). Males have the highest levels of lasted four hours. The female lays eggs at cantharidin and they transfer it to females once, and the eggs are distinguished by a during copulation. Adult blister beetles yellow color and arranged in a wonderful feed on alfalfa leaves and flowers in the way. The female started laying eggs in United States, but the real problem lies in the last week of January, and after the secretion of beetles to the cantharidin finishing laying the eggs, you then go to substance that toxicity livestock, the wheat fields for feeding until death especially horses, when they are see Figure (1). accidentally consumed in feed (Schmitz, The results agree with Selander and 1989). Fasulo (2000) that a blister beetle, M. Many of the common species of proscarabaeus, dig an eggs chamber and blister beetles contain cantharidin lay eggs inside. There are some species (Spanish-fly), a substance that will cause that lay eggs on the leaves of the plant. blisters when applied to the skin (Beasley Although the female M. proscarabaeus et al., 1983). Ward (1985) reported that laid eggs once in January, the M. rugosus cantharidin is a stable chemical and long- females deposit their eggs once in term health threat to nearly all livestock, November and twice in December particularly horses that are fed (Whitehead, 1991). The Meloe female contaminated alfalfa hay. Research forms an egg chamber 2 to 3 cm deep in reports indicate cantharidin toxicosis can the ground and lays several batches of be induced in dairy and beef cattle, goats yellow eggs (Bohac and Winkler, 1964). and sheep; other reports include rapist, 5. Significance of the blister beetles: hedgehogs, mice and dogs (Graziano et

El-Sheikh and El-Tokhy, 2020 al., 1987). Cases of human death also According to the previously have been reported. However, horses mentioned results, the presence of the appear to be more susceptible to toxic blister beetle M. proscarabaeus as a new effects of this potent chemical than other insect pest in El- Farafra Oasis may bring livestock. Although the toxic effects of us to ring the dangerous bell about the cantharidin to all livestock and human, great loss and damage that threat our blister beetles use this fluid and related legume crops and all livestock in such analogs as defensive compounds against new reclaimed and cultivated areas in larger herbivores and predators see Egypt. Figure (1). a b

c d

f e

Figure (1): a. Blister beetle feeding on wheat plant. b. Courtship period between male and female. c. Mating and copulation behavior (tail to tail position) of the blister beetle. d. Egg laying holes excavated by adult females. e. Egg mass of the blister beetle Meloe proscarabaeus. f. Cantharidin fluid excreted by adult beetles on beetle leg.

Egypt. J. Plant Prot. Res. Inst. (2020), 3 (1): 73- 82

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